The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.
Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.
Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.
Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.
A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The ability of a substrate to allow the passage of ELECTRONS.
A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).
A cyclododecadepsipeptide ionophore antibiotic produced by Streptomyces fulvissimus and related to the enniatins. It is composed of 3 moles each of L-valine, D-alpha-hydroxyisovaleric acid, D-valine, and L-lactic acid linked alternately to form a 36-membered ring. (From Merck Index, 11th ed) Valinomycin is a potassium selective ionophore and is commonly used as a tool in biochemical studies.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.
Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
Established cell cultures that have the potential to propagate indefinitely.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Glycoproteins found on the membrane or surface of cells.
Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.
A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
A proton ionophore that is commonly used as an uncoupling agent in biochemical studies.
The rate dynamics in chemical or physical systems.
Elements of limited time intervals, contributing to particular results or situations.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.
A proton ionophore. It is commonly used as an uncoupling agent and inhibitor of photosynthesis because of its effects on mitochondrial and chloroplast membranes.
Cell membranes associated with synapses. Both presynaptic and postsynaptic membranes are included along with their integral or tightly associated specializations for the release or reception of transmitters.
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.
Transport proteins that carry specific substances in the blood or across cell membranes.
Use of electric potential or currents to elicit biological responses.
One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
Compounds that contain three methine groups. They are frequently used as cationic dyes used for differential staining of biological materials.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.
Ions with the suffix -onium, indicating cations with coordination number 4 of the type RxA+ which are analogous to QUATERNARY AMMONIUM COMPOUNDS (H4N+). Ions include phosphonium R4P+, oxonium R3O+, sulfonium R3S+, chloronium R2Cl+
Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
A polyether antibiotic which affects ion transport and ATPase activity in mitochondria. It is produced by Streptomyces hygroscopicus. (From Merck Index, 11th ed)
A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
The relationship between the dose of an administered drug and the response of the organism to the drug.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.
A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)
Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.
A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Cytochromes of the c type that are found in eukaryotic MITOCHONDRIA. They serve as redox intermediates that accept electrons from MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX III and transfer them to MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX IV.
Proteins involved in the transport of specific substances across the membranes of the MITOCHONDRIA.
Mitochondria in hepatocytes. As in all mitochondria, there are an outer membrane and an inner membrane, together creating two separate mitochondrial compartments: the internal matrix space and a much narrower intermembrane space. In the liver mitochondrion, an estimated 67% of the total mitochondrial proteins is located in the matrix. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p343-4)
Proteins found in any species of bacterium.
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions. Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes. Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.
Minute projections of cell membranes which greatly increase the surface area of the cell.
The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
The thin layers of tissue that surround the developing embryo. There are four extra-embryonic membranes commonly found in VERTEBRATES, such as REPTILES; BIRDS; and MAMMALS. They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION. These membranes provide protection and means to transport nutrients and wastes.
Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.
Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.
Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
Contractile tissue that produces movement in animals.
Multisubunit enzymes that reversibly synthesize ADENOSINE TRIPHOSPHATE. They are coupled to the transport of protons across a membrane.
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Proteins encoded by the mitochondrial genome or proteins encoded by the nuclear genome that are imported to and resident in the MITOCHONDRIA.
A closely related group of toxic substances elaborated by various strains of Streptomyces. They are 26-membered macrolides with lactone moieties and double bonds and inhibit various ATPases, causing uncoupling of phosphorylation from mitochondrial respiration. Used as tools in cytochemistry. Some specific oligomycins are RUTAMYCIN, peliomycin, and botrycidin (formerly venturicidin X).
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.
One of the POTASSIUM CHANNEL BLOCKERS, with secondary effect on calcium currents, which is used mainly as a research tool and to characterize channel subtypes.
Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)
Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.
The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.
Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.
A fluorescent probe with low toxicity which is a potent substrate for P-glycoprotein and the bacterial multidrug efflux transporter. It is used to assess mitochondrial bioenergetics in living cells and to measure the efflux activity of P-glycoprotein in both normal and malignant cells. (Leukemia 1997;11(7):1124-30)
Chemical agents that uncouple oxidation from phosphorylation in the metabolic cycle so that ATP synthesis does not occur. Included here are those IONOPHORES that disrupt electron transfer by short-circuiting the proton gradient across mitochondrial membranes.
Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)
Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.
An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.
Measurement of the intensity and quality of fluorescence.
The sum of the weight of all the atoms in a molecule.
A family of intracellular CYSTEINE ENDOPEPTIDASES that play a role in regulating INFLAMMATION and APOPTOSIS. They specifically cleave peptides at a CYSTEINE amino acid that follows an ASPARTIC ACID residue. Caspases are activated by proteolytic cleavage of a precursor form to yield large and small subunits that form the enzyme. Since the cleavage site within precursors matches the specificity of caspases, sequential activation of precursors by activated caspases can occur.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.
Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.
An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a serine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and serine and 2 moles of fatty acids.
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
A class of drugs that act by selective inhibition of calcium influx through cellular membranes.
The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.
Cell membrane glycoproteins that form channels to selectively pass chloride ions. Nonselective blockers include FENAMATES; ETHACRYNIC ACID; and TAMOXIFEN.
Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.
Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.
The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.
Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.
Structures which are part of the CELL MEMBRANE or have cell membrane as a major part of their structure.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
A family of 3,6-di(substituted-amino)-9-benzoate derivatives of xanthene that are used as dyes and as indicators for various metals; also used as fluorescent tracers in histochemistry.
The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.
A 37-amino acid residue peptide isolated from the scorpion Leiurus quinquestriatus hebraeus. It is a neurotoxin that inhibits calcium activated potassium channels.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Proteins prepared by recombinant DNA technology.
An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
Potassium channels where the flow of K+ ions into the cell is greater than the outward flow.
The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).
Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.
A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.
Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.
The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.
Potassium channels that contain two pores in tandem. They are responsible for baseline or leak currents and may be the most numerous of all K channels.
Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.
An increase in MITOCHONDRIAL VOLUME due to an influx of fluid; it occurs in hypotonic solutions due to osmotic pressure and in isotonic solutions as a result of altered permeability of the membranes of respiring mitochondria.
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.
Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
Functionally and structurally differentiated, purple-pigmented regions of the cytoplasmic membrane of some strains of Halobacterium halobium. The membrane develops under anaerobic conditions and is made almost entirely of the purple pigment BACTERIORHODOPSINS. (From Singleton & Sainsbury Dictionary of Microbiology and Molecular Biology, 2d ed)
A cell line derived from cultured tumor cells.
The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)
A short pro-domain caspase that plays an effector role in APOPTOSIS. It is activated by INITIATOR CASPASES such as CASPASE 9. Isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.
A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.
The fluid inside CELLS.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
Electron transfer through the cytochrome system liberating free energy which is transformed into high-energy phosphate bonds.
A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.
A group of cytochromes with covalent thioether linkages between either or both of the vinyl side chains of protoheme and the protein. (Enzyme Nomenclature, 1992, p539)
The mitochondria of the myocardium.
An element in the alkali metals family. It has the atomic symbol Li, atomic number 3, and atomic weight [6.938; 6.997]. Salts of lithium are used in treating BIPOLAR DISORDER.
Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.
The measurement of frequency or oscillation changes.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
A highly neurotoxic polypeptide from the venom of the honey bee (Apis mellifera). It consists of 18 amino acids with two disulfide bridges and causes hyperexcitability resulting in convulsions and respiratory paralysis.
The synapse between a neuron and a muscle.
Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
An antibiotic substance produced by Streptomyces species. It inhibits mitochondrial respiration and may deplete cellular levels of ATP. Antimycin A1 has been used as a fungicide, insecticide, and miticide. (From Merck Index, 12th ed)
The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
A large subphylum of mostly marine ARTHROPODS containing over 42,000 species. They include familiar arthropods such as lobsters (NEPHROPIDAE), crabs (BRACHYURA), shrimp (PENAEIDAE), and barnacles (THORACICA).
The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.
The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.
Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.
A fold of the mucous membrane of the CONJUNCTIVA in many animals. At rest, it is hidden in the medial canthus. It can extend to cover part or all of the cornea to help clean the CORNEA.
A class of chemicals derived from barbituric acid or thiobarbituric acid. Many of these are GABA MODULATORS used as HYPNOTICS AND SEDATIVES, as ANESTHETICS, or as ANTICONVULSANTS.
The inner layer of CHOROID, also called the lamina basalis choroideae, located adjacent to the RETINAL PIGMENT EPITHELIUM; (RPE) of the EYE. It is a membrane composed of the basement membranes of the choriocapillaris ENDOTHELIUM and that of the RPE. The membrane stops at the OPTIC NERVE, as does the RPE.
Proteins obtained from ESCHERICHIA COLI.
Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.
Integral membrane proteins that transport protons across a membrane. This transport can be linked to the hydrolysis of ADENOSINE TRIPHOSPHATE. What is referred to as proton pump inhibitors frequently is about POTASSIUM HYDROGEN ATPASE.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
Refers to animals in the period of time just after birth.
Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.
An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide.
A non-penetrating amino reagent (commonly called SITS) which acts as an inhibitor of anion transport in erythrocytes and other cells.

Automatic activity in depolarized guinea pig ventricular myocardium. Characteristics and mechanisms. (1/24936)

Membrane potential was changed uniformly in segments, 0.7-1.0 mm long, of guinea pig papillary muscles excised from the right ventricle by using extracellular polarizing current pulses applied across two electrically insulated cf preparations superfused with Tyrode's solution at maximum diastolic membrane potentials ranging from-35.2+/-7.5 (threshold) to +4.0+/-9.2 mV. The average maximum dV/dt of RAD ranged from 17.1 to 18.0 V/sec within a membrane potential range of -40 to +20 mV. Raising extracellular Ca2+ concentration [Ca2+]0 from 1.8 to 6.8 mM, or application of isoproterenol (10(-6)g/ml) enhanced the rate of RAD, but lowering [Ca2+]0 to 0.4 mM or exposure to MnCl2 (6 mM) abolished RAD. RAD were enhanced by lowering extracellular K+ concentration [K+]0 from 5.4 to 1.5 mM. RAD were suppressed in 40% of fibers by raising [K+]0 to 15.4 mM, and in all fibers by raising [K+]0 to 40.4 mM. This suppression was due to increased [K+]0 and not to K-induced depolarization because it persisted when membrane potential was held by means of a conditioning hyperpolarizing puled gradually after maximum repolarization. These observations suggest that the development of RAD in depolarized myocardium is associated with a time-dependent decrease in outward current (probably K current) and with increase in the background inward current, presumably flowing through the slow cha-nel carrying Ca or Na ions, or both.  (+info)

Effect of electrotonic potentials on pacemaker activity of canine Purkinje fibers in relation to parasystole. (2/24936)

Isolated false tendons excised form dog hearts were mounted in a three-chamber tissue bath. Isotonic sucrose solution was perfused in the central chamber to provide a region of depressed conductivity between the fiber segments in chambers 1 and 3, which were perfused with Tyrode's solution. The electrotonic influence of spontaneous or driven responses evoked in chamber 3 during the first half of the spontaneous cycle of a chamber 1 peacemaker delayed the next spontaneous discharge. This effect changed to acceleration when the chamber 3 segment fired during the second half of the spontaneous cycle. We found that subthreshold depolarizing current pulses 50-300 msec applied across the sucrose gap caused similar degrees of delay or acceleration. Furthermore, hyperpolarizing currents caused the reverse pattern. The results indicate that the discharge pattern of a parasystolic focus may be altered by the electrotonic influence of activity in the surrounding tissue. The significance of these findings is considered in relation to the mechanism of production of parasystolic rhythms.  (+info)

Effect of paracetamol (acetaminophen) on gastric ionic fluxes and potential difference in man. (3/24936)

Paracetamol has replaced aspirin as the analgesic of choice in many situations. The major reason is the damaging effect of aspirin on gastric mucosa. Alterations in gastric ionic fluxes and potential difference provide measures of aspirin-induced structural damage. We studied the effect of large doses of paracetamol (acetaminophen 2-0 g) on gastric ionic fluxes in man. In addition, the effect of 2-0 g paracetamol on gastric potential difference was compared with that of 600 mg aspirin. In contrast with salicylates, paracetamol caused no significant alteration in movement of H+ and Na+ ions over control periods. Aspirin causes a significant fall in transmucosal potential difference (PD) across gastric mucosa of 15 mv, while paracetamol cuased no significant change. Paracetamol in a dose four times that recommended does not alter gastric ionic fluxes or potential difference. These studies support choice of paracetamol as analgesic over aspirin where damage to gastric mucosa may be critical.  (+info)

Dopamine stimulates salivary duct cells in the cockroach Periplaneta americana. (4/24936)

This study examines whether the salivary duct cells of the cockroach Periplaneta americana can be stimulated by the neurotransmitters dopamine and serotonin. We have carried out digital Ca2+-imaging experiments using the Ca2+-sensitive dye fura-2 and conventional intracellular recordings from isolated salivary glands. Dopamine evokes a slow, almost tonic, and reversible dose-dependent elevation in [Ca2+]i in the duct cells. Upon stimulation with 10(-)6 mol l-1 dopamine, [Ca2+]i rises from 48+/-4 nmol l-1 to 311+/-43 nmol l-1 (mean +/- s.e.m., N=18) within 200-300 s. The dopamine-induced elevation in [Ca2+]i is absent in Ca2+-free saline and is blocked by 10(-)4 mol l-1 La3+, indicating that dopamine induces an influx of Ca2+ across the basolateral membrane of the duct cells. Stimulation with 10(-)6 mol l-1 dopamine causes the basolateral membrane to depolarize from -67+/-1 to -41+/-2 mV (N=10). This depolarization is also blocked by La3+ and is abolished when Na+ in the bath solution is reduced to 10 mmol l-1. Serotonin affects neither [Ca2+]i nor the basolateral membrane potential of the duct cells. These data indicate that the neurotransmitter dopamine, which has previously been shown to stimulate fluid secretion from the glands, also stimulates the salivary duct cells, suggesting that dopamine controls their most probable function, the modification of primary saliva.  (+info)

Trans-synaptically induced bursts in regular spiking non-pyramidal cells in deep layers of the cat motor cortex. (5/24936)

In deep layers of the cat motor cortex, we have investigated the properties of neurons displaying trans-synaptically induced bursts. In in vivo experiments, extracellularly recorded burst neurons were separated into two subtypes based on their dependence on stimulation sites, the medullary pyramid or the ventrolateral (VL) thalamic nucleus, from which bursts of 10-20 spikes were triggered. The spike amplitude attenuation and frequency adaptation during a burst were more prominent in pyramid-dependent burst neurons than in VL-dependent burst neurons. Intracellular recordings in in vivo experiments revealed that pyramid-dependent bursts emerged from a long-lasting depolarization, while each spike during a VL-dependent burst was narrow in half-width and was followed by a fast AHP, similar to fast spiking neurons. In in vitro slice experiments, intracellular recordings were obtained from neurons that displayed a burst of attenuated spikes emerging from a long-lasting depolarization, and were also obtained from fast spiking neurons. They were morphologically recovered to be multipolar cells with sparsely spiny dendrites and local axonal networks, suggesting that they are inhibitory interneurons. The multipolar neurons displaying bursts of attenuated spikes may mediate the recurrent inhibition of pyramidal tract cells.  (+info)

Low resting potential and postnatal upregulation of NMDA receptors may cause Cajal-Retzius cell death. (6/24936)

Using in situ patch-clamp techniques in rat telencephalic slices, we have followed resting potential (RP) properties and the functional expression of NMDA receptors in neocortical Cajal-Retzius (CR) cells from embryonic day 18 to postnatal day 13, the time around which these cells normally disappear. We find that throughout their lives CR cells have a relatively depolarized RP (approximately -50 mV), which can be made more hyperpolarized (approximately -70 mV) by stimulation of the Na/K pump with intracellular ATP. The NMDA receptors of CR cells are subjected to intense postnatal upregulation, but their similar properties (EC50, Hill number, sensitivity to antagonists, conductance, and kinetics) throughout development suggest that their subunit composition remains relatively homogeneous. The low RP of CR cells is within a range that allows for the relief of NMDA channels from Mg2+ blockade. Our findings are consistent with the hypothesis that CR cells may degenerate and die subsequent to uncontrolled overload of intracellular Ca2+ via NMDA receptor activation by ambient glutamate. In support of this hypothesis we have obtained evidence showing the protection of CR cells via in vivo blockade of NMDA receptors with dizocilpine.  (+info)

UCP4, a novel brain-specific mitochondrial protein that reduces membrane potential in mammalian cells. (7/24936)

Uncoupling proteins (UCPs) are a family of mitochondrial transporter proteins that have been implicated in thermoregulatory heat production and maintenance of the basal metabolic rate. We have identified and partially characterized a novel member of the human uncoupling protein family, termed uncoupling protein-4 (UCP4). Protein sequence analyses showed that UCP4 is most related to UCP3 and possesses features characteristic of mitochondrial transporter proteins. Unlike other known UCPs, UCP4 transcripts are exclusively expressed in both fetal and adult brain tissues. UCP4 maps to human chromosome 6p11.2-q12. Consistent with its potential role as an uncoupling protein, UCP4 is localized to the mitochondria and its ectopic expression in mammalian cells reduces mitochondrial membrane potential. These findings suggest that UCP4 may be involved in thermoregulatory heat production and metabolism in the brain.  (+info)

Individual subunits contribute independently to slow gating of bovine EAG potassium channels. (8/24936)

The bovine ether a go-go gene encodes a delayed rectifier potassium channel. In contrast to other delayed rectifiers, its activation kinetics is largely determined by the holding potential and the concentration of extracellular Mg2+, giving rise to slowly activating currents with a characteristic sigmoidal rising phase. Replacement of a single amino acid in the extracellular linker between transmembrane segments S3 and S4 (L322H) strongly reduced the prepulse dependence and accelerated activation by 1 order of magnitude. In addition, compared with the wild type, the half-activation voltage of this mutant was shifted by more than 30 mV to more negative potentials. We used dimeric and tetrameric constructs of the bovine eag1 gene to analyze channels with defined stoichiometry of mutated and wild-type subunits within the tetrameric channel complexes. With increasing numbers of mutated subunits, the channel activation was progressively accelerated, and the sigmoidicity of the current traces was reduced. Based on a quantitative analysis, we show that the slow gating, typical for EAG channels, is mediated by independent conformational transitions of individual subunits, which gain their voltage dependence from the S4 segment. At a given voltage, external Mg2+ increases the probability of a channel subunit to be in the slowly activating conformation, whereas mutation L322H strongly reduces this probability.  (+info)

purpose. Tetraphenylphosphonium (TPP+) is a permeant lipophilic cation that accumulates in cultured cells and tissues as a function of the electrical membrane potential across the plasma membrane. This study was undertaken to determine whether TPP+ can be used for assessing membrane potential in intact lenses in organ culture.. methods. Rat lenses were cultured in media containing 10 μM TPP+ and a tracer level of 3H-TPP+ for various times. 3H-TPP+ levels in whole lenses or dissected portions of lenses were determined by liquid scintillation counting. Ionophores, transport inhibitors, and neurotransmitters were also added to investigate their effects on TPP+ uptake.. results. Incubation of lenses in low-K+ balanced salt solution and TC-199 medium, containing physiological concentrations of Na+ and K+, led to a biphasic accumulation of TPP+ in the lens that approached equilibrium by 12 to 16 hours of culture. The TPP+ equilibrated within 1 hour in the epithelium but penetrated more slowly into ...
Ceballos, Cesar C., Antonio C. Roque, and Ricardo M. Leão. A negative slope conductance of the persistent sodium current prolongs subthreshold depolarizations. Biophysical journal 113.10 (2017): 2207-2217.
TY - JOUR. T1 - Sex differences in membrane potential in the intact perfused rat liver. AU - Weisiger, R. A.. AU - Fitz, J. G.. PY - 1988. Y1 - 1988. N2 - The electrical potential difference across the plasma membrane was compared in paired livers from male and female rats perfused single-pass with Krebs-bicarbonate buffer. Variability in the membrane potential measured for different cells within the same liver was small (SD = 1.3 mV). The mean membrane potential was 5.1 mV more negative for male livers than for female livers (-30.3 ± 0.6 vs. -25.2 ± 1.0 mV, P , 0.001), and the female liver in all nine pairs studied. No correlation between membrane potential and perfusion rate was seen. Variability among female livers was more than twice as great (range -19.6 to -30.0 mV) as for male livers (range -26.7 to -31.9 mV). These results suggest that hepatic membrane potential may be modulated by sex hormone levels, which are more variable in female animals. Because the hepatic uptake of bile acids ...
can be generated along the axon while the threshold potential is reached. The greater the strength of the stimulus, causing the membrane depolarisation process to occur. Subsequently, some [[Sodium_voltage-gated_ion_channels,voltage-gated Na,sup,+,/sup, channels]] are opened, allowing the [[Sodium,Na,sup,+,/sup,]] ions to move across the membrane into the intracellular environment. The neuronal membrane now becomes slightly positive, relative to the outside of membrane. As the membrane potential shift from -70 mV to more positive value, the threshold potential is reached, causing all of the voltage-gated Na+ channel to open, creating a rapid rise of membrane potential value into the maximum, +60 mV. During depolarisation, the membrane potential value would not exceed the amount of +60mV as it is the equilibrium potential of Na,sup,+,/sup, ,ref,,/ref ...
Peak current‐voltage relationships for ICa,L in fetal ventricular cardiomyocytes. WT calmodulin data are repeated in each panel for clarity of presentation. N
Electrical activity of enzymatically isolated, smooth muscle cells from hog carotid arteries was recorded under current clamp and voltage clamp. Under the experimental conditions, membrane potential usually was not stable, and spontaneous hyperpolarizing transients of approximately 100-msec duration were recorded. The amplitude of the transients was markedly voltage dependent and ranged from about 20 mV at a membrane potential of 0 mV to undetectable at membrane potentials negative to -60 mV. Under voltage clamp, transient outward currents displayed a similar voltage dependency. These fluctuations reflect a K+ current; they were abolished by 10 mM tetraethylammonium chloride, a K+ channel blocker, and the current fluctuations reversed direction in high extracellular K+ concentration. Modulators of intracellular Ca2+ concentration also affected electrical activity. Lowering intracellular Ca2+ concentration by addition of 10 mM EGTA to the pipette solution or suppressing sarcoplasmic reticulum ...
However, the first question before addressing this problems is whether outside binding is relevant at all. Brand[2] stated that for permeabilized cells outside binding may be ignored for high mitochondrial membrane potential. Initially, this seemed to be confirmed by our own initial sensitivity studies. Using outside binding correction factors similar to the inside ones and using protein content as marker, changing the outside binding correction factor by several hundred percent caused comparable small changes in reasonable high membrane potentials and negligible changes in delta delta Psi values for permeabilized cells. However, with growing experience it became evident that unspecific binding may be underestimated by this approach, resulting in obviously too high membrane potentials especially for states of known low potential. Part of the unreasonable high membrane potential could be explained by wrong assumptions for the amount of mitochondrial protein (Pmt). Non the less, modeling of the ...
Short muscle fibers (less than 1.5 mm) from the m. lumbricalis IV digiti of Rana pipiens were voltage-clamped at -100 mV with a two-microelectrode technique, in normal Ringers solution containing 10(-6) g/ml tetrodotoxin. The activation curve relating peak tension to membrane potential could be shifted toward more negative or less negative potential values by hyperpolarizing or depolarizing the fiber membrane to -130, -120, or -70 mV, respectively, which indicates that contractile threshold depends on the fiber membrane potential. Long (greater than 5 s) depolarizing (90 mV) pulses induce prolonged contractile responses showing a plateau and a rapid relaxation phase similar to K contractures. Conditioning hyperpolarizations prolong the time course of these responses, while conditioning depolarizations shorten it. The shortening of the response time course, which results in a decrease of the area under the response, is dependent on the amplitude and duration of the conditioning depolarization. ...
In rat mesenteric arteries, the ability of ACh to evoke hyperpolarization of smooth muscle cells and consummate dilatation relies on an increase in endothelial cell cytosolic free [Ca2+] and activation of Ca2+-activated K+ channels (KCa). The time course of average and spatially organized rises in endothelial cell [Ca2+]i and concomitant effects on membrane potential were investigated in individual cells of pressurized arteries and isolated sheets of native cells stimulated with ACh. In both cases, ACh stimulated a sustained and oscillating rise in endothelial cell [Ca2+]i. Overall, the oscillations remained asynchronous between cells, yet occasionally localized intercellular coordination became evident. In pressurized arteries, repetitive waves of Ca2+ moved longitudinally across endothelial cells, and depended on Ca2+-store refilling. The rise in endothelial cell Ca2+ was associated with sustained hyperpolarization of endothelial cells in both preparations. This hyperpolarization was also evident when
Coupled interactions among solute diffusions, membrane surface potentials, and opposing enzyme reactions as a mechanism for active transports performed with biomimetic membranes
It plots for me Hodgkin-Huxley activation and inactivation curves. A little explanation: The Hodgkin-Huxley formalism is a way to describe how neurons transmit signals. Neurons transmit signals by electric impulses. There is always a voltage difference between the interior and the exterior of the cell(called membrane potential). If i change this potential somewhere, this temporary change will spread across the cells surface, like a wave. The mechanisms responsible for this process are molecules in the cell membrane(called ion channels), which can open to let ions flow trough, which causes change in the membrane potential. There are tons of different ion channels, but most of them can be described with the Hodgkin-Huxley formalism. These curves describe how much will be these channels open ( 0-closed; 1-fully open) at different membrane potential values. To make things more complicated each ion channel is modeled by 2 curves (activation and inactivation) and the product at a current membrane ...
It plots for me Hodgkin-Huxley activation and inactivation curves. A little explanation: The Hodgkin-Huxley formalism is a way to describe how neurons transmit signals. Neurons transmit signals by electric impulses. There is always a voltage difference between the interior and the exterior of the cell(called membrane potential). If i change this potential somewhere, this temporary change will spread across the cells surface, like a wave. The mechanisms responsible for this process are molecules in the cell membrane(called ion channels), which can open to let ions flow trough, which causes change in the membrane potential. There are tons of different ion channels, but most of them can be described with the Hodgkin-Huxley formalism. These curves describe how much will be these channels open ( 0-closed; 1-fully open) at different membrane potential values. To make things more complicated each ion channel is modeled by 2 curves (activation and inactivation) and the product at a current membrane ...
The modeling of particle transport involves anomalous diffusion, (x²(t) ) ∝ t{sup α} with α ≠ 1, with subdiffusive transport corresponding to 0 , α , 1 and superdiffusive transport to α , 1. These anomalies give rise to fractional advection-dispersion equations with memory in space and time. The usual Boltzmann equation, with only isolated binary collisions, is Markovian and, in particular, the contributions of the three-particle distribution function are neglected. We show that the inclusion of higher-order distribution functions give rise to an exact, non-Markovian Boltzmann equation with resulting transport equations for mass, momentum, and kinetic energy with memory in both time and space. The two- and the three-particle distribution functions are considered under the assumption that the two- and the three-particle correlation functions are translationally invariant that allows us to obtain advection-dispersion equations for modeling transport in terms of spatial and temporal ...
In the voltageclamp configuration, a current is injected into the cell via a negative feedback loop to compensate changes in membrane potential. This technique is the refinement of the voltage clamp. Neuroscience is available from oxford university press. Sep 29, 20 this screencast describes iv and vi relations derived from patch or current clamp data, and how to calculate conductance or resistance from the data. Still more recently, a technique has been invented, patch clamping, that makes it possible to voltage clamp small regions of the nerve cell membrane, and look at the responses of individual ion channels to changes in voltage across the membrane. Oct 28, 20 the voltage clamp is a technique used to control the voltage across the membrane of a small or isopotential area of a nerve cell by an electronic feedback circuit. Alternatively, the current clamp technique can be used. Identification and regulation of wholecell chloride currents. Theory the basis of the voltage clamp may be ...
1. A method is described that enables the calculation of resting membrane potential from the electrolyte and water contents in blood plasma and in a sample of human muscle tissue obtained by the percutaneous needle-biopsy technique. In this calculation, the previously described equations for calculating resting membrane potential via the intra- and extra-cellular distribution of chloride were combined with the equation utilizing potassium distribution over the cell membrane.. 2. The method of calculation was applied to 60 healthy subjects divided into three groups aged 19-40, 41-60 and 61-85 years. The calculated resting membrane potential in the subjects as a whole was −88.4 mV (SD 1.35; n = 60). A lower value was observed in the group aged 61-85 years (−87.7 mV, SD 1.0; n = 12) than in the group aged 19-40 years (−88.6 mV; SD 1.4; n = 32). No difference was observed between female and male subjects.. 3. The RMP calculated with the present method in 60 healthy subjects was also compared ...
Under the voltage clamp condition, the K inactivation was analyzed in cells bathed in the isosmotic KCl Lophius-Ringer solution. After conditioning hyperpolarization, the cells respond to depolarizations with increased K permeability, which in turn is decreased during maintained depolarizations. The steady-state levels of the K inactivation as a function of the membrane potential are related by an S-shaped curve similar to that which describes the steady-state Na inactivation in the squid giant axon. TEA reduced the K conductance by a factor which is independent of the potential, and without a shift of the inactivation curve along the voltage axis. The rapid phase of the K activation is less susceptible to TEA than the slow phase of the K activation. Hyperpolarizing steps remove the K inactivation, the rate of the removal being faster the larger the hyperpolarization from the standard potential of about -60 mv.. ...
But this polarity is not static; it is actually a very tenuous thing. With respect to which, it is of utmost importance to realize that this polarity is not the result of the asymmetry or lopsideness of the arrangement of its atoms (if that was the case then its polarity really would be static--this being the biggest mistake conventional theorists are making). Rather this polarity is the result of the asymmetry or lopsideness of its electrical gradients, what I refer to hereafter as the H2O molecules intrinsic electrical gradients. And this is especially important with repect to the fact that when an H2O molecule makes hydrogen bonds with adjacent H2O molecules additional electrical gradients are brought into play from this adjacent H2O molecule. And these additional electrical gradients, what I will refer to hereafter as incidental (or you could use external rather than incidental) electrical gradients, oppose or neutralize the H2O molecules intrinsic electrical gradients. The net effect ...
Voltage-gated n-type K(V) and Ca(2+)-activated K+ [K(Ca)] channels were studied in cell-attached patches of activated human T lymphocytes. The single-channel conductance of the K(V) channel near the resting membrane potential (Vm) was 10 pS with low K+ solution in the pipette, and 33 pS with high K+ solution in the pipette. With high K+ pipette solution, the channel showed inward rectification at positive potentials. K(V) channels in cell-attached patches of T lymphocytes inactivated more slowly than K(V) channels in the whole-cell configuration. In intact cells, steady state inactivation at the resting membrane potential was incomplete, and the threshold for activation was close to Vm. This indicates that the K(V) channel is active in the physiological Vm range. An accurate, quantitative measure for Vm was obtained from the reversal potential of the K(V) current evoked by ramp stimulation in cell-attached patches, with high K+ solution in the pipette. This method yielded an average resting Vm ...
Gonadotropin Inhibitory Hormone (GnIH) expressing neurons, through projections and interactions with gonadotropin releasing hormone (GnRH)-expressing and POMC-expressing neurons in the arcuate nucleus of the hypothalamus are suggested to serve as a fulcrum for neuroendocrine regulation of reproduction and appetite. Relatively little is known of the intrinsic membrane and extrinsic synaptic mechanisms regulating activity of GnIH neurons. Here, using the whole-cell patch clamp technique, the electrophysiological and pharmacological profile of GFP-labelled GnIH neurons has been investigated in rats in vitro.. Whole-cell recordings were obtained from 35 GnIH-GFP expressing neurons of the rat dorsomedial hypothalamus (DMH). Passive membrane properties included a mean resting membrane potential, firing rate and input resistance of 39.3 ± 0.7 mV, 0.94 ± 0.18 Hz and 1489 ± 98 mΩ, respectively. DMH GnIH neurons expressed: a 4-AP-sensitive transient outward rectification in 91% neurons; a ...
Kretzberg J, Warzecha AK, Egelhaaf M JOURNAL OF COMPUTATIONAL NEUROSCIENCE 11 (2): 153-164 2001 The neural encoding of sensory stimuli is usually investigated for spike responses, although many neurons are known to convey information by graded membrane potential changes. We compare by model simulations how well different dynamical stimuli can be discriminated on the basis of spiking or graded responses. Although a continuously varying membrane potential contains more information than binary spike trains, we find situations where different stimuli can be better discriminated on the basis of spike responses than on the basis of graded responses. Spikes can be superior to graded membrane potential fluctuations if spikes sharpen the temporal structure of neuronal responses by amplifying fast transients of the membrane potential. Such fast membrane potential changes can be induced deterministically by the stimulus or can be due to membrane potential noise that is influenced in its statistical ...
Intracellular recordings were obtained from rat neocortical neurons in vitro. The current-voltage-relationship of the neuronal membrane was investigated using current- and single-electrode-voltage-clamp techniques. Within the potential range up to 25 mV positive to the resting membrane potential (RMP: -75 to -80 mV) the steady state slope resistance increased with depolarization (i.e. steady state inward rectification in depolarizing direction). Replacement of extracellular NaCl with an equimolar amount of choline chloride resulted in the conversion of the steady state inward rectification to an outward rectification, suggesting the presence of a voltage-dependent, persistent sodium current which generated the steady state inward rectification of these neurons. Intracellularly injected outward current pulses with just subthreshold intensities elicited a transient depolarizing potential which invariably triggered the first action potential upon an increase in current strength. ...
In this lesson I want to talk about membrane potentials and the role they play in nerve transmission.. So first - what is a membrane potential. Anytime you hear potential related to nerves - think electrical charge. So the membrane potential is just the electrical charge across a membrane. In the nerves, we have a resting potential and an action potential. This should be pretty self-explanatory. The resting potential is when nothing is happening - the nerve is just resting. Well look at this more in a minute, but know that the resting membrane potential - or the resting electrical charge is negative 70 mV - meaning its more negative on the inside than the outside. The other type we have is an Action Potential - as you can see - this is when there is an ACTION happening - so an action potential is sending a stimulus to create a response somewhere in the body. The charge in an Action Potential is more positive - well look at specifics in a minute.. So when I say the resting potential is ...
TY - JOUR. T1 - Effect of the non-linear membrane potential on the migration of ionic species in concrete. AU - Marriaga, J.L.. AU - Claisse, Peter A.. PY - 2008/11. Y1 - 2008/11. KW - Concrete. KW - Electromigration. KW - Chloride modelling. KW - Membrane potential. KW - Ion transport. U2 - 10.1016/j.electacta.2008.11.031. DO - 10.1016/j.electacta.2008.11.031. M3 - Article. VL - 54. SP - 2761. EP - 2769. JO - Electrochimica Acta. JF - Electrochimica Acta. SN - 0013-4686. IS - 10. ER - ...
TY - JOUR. T1 - Hypoxia in striatal and cortical neurones. T2 - Membrane potential and Ca2+ measurements. AU - Pisani, Antonio. AU - Calabresi, Paolo. AU - Bernardi, Giorgio. PY - 1997. Y1 - 1997. N2 - Simultaneous measurements of membrane potential and intracellular Ca2+ were used to study the effects of hypoxia on striatal and cortical neurones. Striatal neurones responded to hypoxia with a reversible membrane depolarization coupled with a transient increase in intracellular Ca2+. Thirty minutes of hypoxia caused an irreversible membrane depolarization associated with a massive raise in Ca2+ levels, leading to cell death. Conversely, cortical neurones were more resistant to O2 deprivation. Hypoxia (4-10 min) induced minimal changes in both membrane potential and Ca2+ signals. Longer periods (20-30 min) caused an initial membrane hyperpolarization followed by a large but reversible depolarization coupled with a transient increase in Ca2+ signals. These results support the hypothesis of a ...
TY - JOUR. T1 - Spike-Threshold Adaptation Predicted by Membrane Potential Dynamics In Vivo. AU - Fontaine, Bertrand. AU - Peña, José Luis. AU - Brette, Romain. N1 - Copyright: Copyright 2014 Elsevier B.V., All rights reserved.. PY - 2014/4. Y1 - 2014/4. N2 - Neurons encode information in sequences of spikes, which are triggered when their membrane potential crosses a threshold. In vivo, the spiking threshold displays large variability suggesting that threshold dynamics have a profound influence on how the combined input of a neuron is encoded in the spiking. Threshold variability could be explained by adaptation to the membrane potential. However, it could also be the case that most threshold variability reflects noise and processes other than threshold adaptation. Here, we investigated threshold variation in auditory neurons responses recorded in vivo in barn owls. We found that spike threshold is quantitatively predicted by a model in which the threshold adapts, tracking the membrane ...
The voltage across a cell membrane is known as the cell membrane potential. Cells that generally have cell membrane potentials are nerve cells that are electrically active....
View Notes - 7 Membrane Potential from KINESIOLOG 1Y03 at McMaster University. Membrane Potential Membrane Potential -1 Two Types of Ion Channels Leakage (nongated) channels always open Gated
Ang II elicited a relatively small inward current (9.7 pA on average in response to 1 μmol/L peptide). However, because of the high input resistance of the cells (0.8 to 0.9 GΩ), this current is sufficient to produce the 7- to 8-mV depolarization consistently observed in current-clamp experiments. Because the cells are slowly active at rest, a depolarization of this magnitude leads to a substantial increase in discharge rate (250% of control). The depolarization (current clamp) or inward current (voltage clamp at −40 to −55 mV) was associated with a decrease in membrane conductance. This reduction of conductance is likely due to closure of K+ channels for the following reasons: First, in the presence of 3.8 mmol/L [K+]o, the current elicited by Ang II reversed polarity very close to EK (Erev, −89 mV; Fig 8A⇑), suggesting that it was carried selectively by K+. Second, raising [K+]o to 10 mmol/L shifted the Erev of the Ang II-induced current to between −60 and −68 mV, a shift that is ...
Manual patch clamp assays: Ionic current measurements. Request a Study Outline from IPST. Whole-cell current amplitude and kinetics measurements verify the results of the interaction of a test article with a selected ionic current. (The popular hERG assay is an example of ionic current assay, saimed specifically at the well-known hERG channel.) The assay is generally used to elucidate the mechanism behind various ion-channel-related arrhythmic events, and uncover ion current inhibition, either as a primary or secondary pharmacology manifestation.. A typical patch clamp study involves a pulse protocol whereby a patched cell is held at an interpulse low enough to prevent the channels from activating/opening. Generally, activation requires a depolarization to a threshold potential. Increasing voltage pulses are applied to the cell and when the voltage applied approaches, and eventually reaches that threshold potential, the current measures across the cell increases as more and more of the ...
In short, since the 1940s a dedicated slew of people have been trying different approaches to solve that equation with a precision that is unheard of in other areas of physics and engineering. All this in the name of shielding us from harmful radiation. This is all good, but why are we having this discussion in the context of synthesis and analysis based reconstructions ? It turns out that the freaks have looked at the Linear Boltzmann Equation through **many** angles. One of these angles is to decompose the flux in some eigenfunctions of the Linear Transport Operator (they are in fact distributions). There are some completude results for 1-D but 2D or 3-D are still really unexplored and not really well understood. Anyway, what was noticed empirically is that solution fluxes always end up following a diffusion equation a few mean free path away from the boundaries or sources. Close to the boundaries or sources, the full transport solution needs those eigendistributions expansions. While you may ...
The reverse use-dependence observed with GLG-V-13 and KMC-IV-84 in the present experiments has been previously reported for methanesulfonalide class III drugs such as dofetilide (Gwilt et al., 1991;Jurkiewicz and Sanguinetti, 1993), E-4031 (Wettwer et al., 1991), d,l-sotalol (Strauss et al., 1970; Hafneret al., 1988), MK-499 (Baskin and Lynch, 1994; Krafte and Volberg, 1994) and sematilide (Krafte and Volberg, 1994). The actual mechanism(s) for reverse use-dependence is/are controversial. The earliest mechanism for reverse use-dependence of action potential duration was advanced by Hondeghem and Snyders (1990). Experimental data from their laboratory demonstrated a time- and voltage-dependent modulation of Ik with quinidine. Quinidine primarily reduced time-dependent outward potassium currents at negative membrane potentials, with blockade of outward potassium currents becoming less pronounced with depolarization (Roden et al., 1988). Later data, however, have failed to demonstrate a similar ...
The results demonstrate that dendritic NMDA spike/plateau potentials can be evoked in TC neurons by local glutamate stimulation on a single dendritic arbor. The potentials had similar electrophysiological and pharmacological properties as NMDA spike/plateau potentials in cortical pyramidal neurons (Schiller et al., 2000; Nevian et al., 2007; Major et al., 2008; Larkum et al., 2009). Weak stimulation elicited a small-amplitude, EPSP-like potential at soma that gradually grew in amplitude with increasing stimulus intensity to a threshold where a marked increase of amplitude was elicited indicating a spike-like potential. Further increase caused an elongation of the potential into a plateau that could last up to several hundred milliseconds. The spike/plateau potentials were selectively blocked by the NMDA-R antagonist CPP. The Ca2+ channel blockers Cd2+, Ni2+ and nimodipine, and the Na+ channel blocker TTX had only minor effects. Even at hyperpolarized membrane potentials (−70 mV or −65 mV), ...
Kv2.1 protein is expressed in female and male arterial myocytes, where its assumed functional role has been as a voltage-gated ion channel that, upon opening, hyperpolarizes the membrane potential of these cells to impact myocyte [Ca2+]i and myogenic tone (16). Here, we propose a model in which Kv2.1 channels have a more complex function to exert opposing actions on vascular smooth muscle. In its canonical role, the opening of conducting Kv2.1 hyperpolarizes arterial myocytes, which decreases the Po of CaV1.2 channels. This lowers [Ca2+]i, inducing relaxation. Our data indicate that Kv2.1 protein has an additional nonconducting structural role in arterial myocytes: to enhance CaV1.2 clustering and activity, thereby increasing [Ca2+]i and inducing contraction. It is paradoxical that Kv2.1 could control both relaxation and contraction in arterial smooth muscle. Notably, we find that the relative contribution of the electrical and structural roles of Kv2.1 to the control of membrane potential and ...
JNeurosci Online ISSN: 1529-2401. The ideas and opinions expressed in JNeurosci do not necessarily reflect those of SfN or the JNeurosci Editorial Board. Publication of an advertisement or other product mention in JNeurosci should not be construed as an endorsement of the manufacturers claims. SfN does not assume any responsibility for any injury and/or damage to persons or property arising from or related to any use of any material contained in JNeurosci.. ...
1. 1. ACh dose-response curves for the radular retractor muscle of Buccinum showed maximum force and membrane depolarisation of 3.3 mV at 50 μmol 1−1 ACh. 2. 2. PCh was found to be almost a full agonist for force and induced higher membrane depolarisations than ACh while BCh was only a partial agonist of very low potency. This suggests an AChR neither muscarinic nor nicotinic in mammalian terminology. 3. 3. Neither muscarine nor nicotine had any direct agonistic effects on the muscle but pre-exposure to nicotine inhibited both force and membrane depolarisation induced by a subsequent dose of ACh. 4. 4. The specific muscarinic and nicotinic antagonists atropine, d-tubocurarine and gallamine all inhibited ACh responses in a dose-dependent manner. 5. 5. Single sucrose-gap recording showed that ACh induced a depolarisation resulting in a contracture. Double sucrose-gap voltage clamp recording showed that 10 μmol 1−1 ACh induced an inward transmembrane current of ca 2 μA. Both ACh-induced ...
All living cells display a difference in electrical potential between their cytoplasm and the extracellular space. This difference in potential across the plasma membrane, commonly referred to as membrane potential, not only constitutes a signal of life, but it also constitutes a source of energy for the translocation of many kinds of molecules in and out of the intracellular space. Changes in the membrane potential are related to a number of cellular events ranging from development to rapid electrical signaling in excitable tissues. For decades, the realm of cellular electrical activity has been limited to the action of ion channels and ionotropic ATPases and transporters. Indeed, the main molecular entities responsible for rapid signaling, such as action potentials and synaptic activity, have been identified. Yet, identification of the link between electrical activity at the plasma membrane and cell proliferation, differentiation and migration remains elusive. The quest to identify this link reached a
For a nerve cell at its resting potential, the forces acting on potassium ions (K+) are: an electrical gradient, pulling K+ inward and a chemical gradient, pushing K+ outward. Suppose a cells membrane potential shifts from -move -numb. What changes in the cells permeability to K+ or An+ could cause a shift? An+ depopulating here. So we bring An+ ions into the cell. So to do this, you change membrane permeability by adding more An+ ion channels. To fill in and label the diagram.. Tell what the flow of potassium and sodium. Label Membrane potential (NV), Resting potential, Action potential, time mess. Explain deportation. Rising potential-more An going into the cell. Falling- Undershoot= potassium ion channels are still inactivated. So they would fall below the resting potential. Graded response vs. action potential-action potential is independent of the stimulus. Graded response potential is everything below the threshold. Things to know: what the threshold is. Intervention-more in the ...
Instantaneous current-voltage relations for α1G channels. (A) Sample current records, with 5 kHz Gaussian filtering, from cell e8612. The initial step to +60
Protocols for antitachycardial pacing including biphasic stimulation administered at, or just above, the diastolic depolarization threshold potential; biphasic or conventional stimulation initiated at, or just above, the diastolic depolarization threshold potential, reduced, upon capture, to below threshold; and biphasic or conventional stimulation administered at a level set just below the diastolic depolarization threshold potential. These protocols result in reliable cardiac capture with a lower stimulation level, thereby causing less damage to the heart, extending battery life, causing less pain to the patient and having greater therapeutic effectiveness. In those protocols using biphasic cardiac pacing, a first and second stimulation phase is administered. The first stimulation phase has a predefined polarity, amplitude and duration. The second stimulation phase also has a predefined polarity, amplitude and duration. The two phases are applied sequentially. Contrary to current thought, anodal
It is present in the plasma membrane. It is powered by ATP. It keeps the concentrations of Na and K ions constant on the two side of the membrane. The pump actively move Na+ ions outside of the cell. It pumps K ions inside of the cell. It moves three Na+ out for each two K+moves inside. Thus this pump establishes resting potential across the membrane. Both ions also leak back across the membrane. But K+ move more easily back to the outside. It adds to the positive charge there. Thus membrane potential of -70mV is established ...
The first step in the generation of an action potential is to depolarize the cell by injecting current into the axon. This will partially depolarize the cell membrane, causing it to become less negative and this change in membrane potential triggers voltage gated Na+ to open. Na+ ions are now free to pass through this channel, resulting in a relatively massive influx of Na+ inside the axon. Since the membrane is now overwhelmingly permeable to Na+ the membrane potential at the top of the spike will be driven close to the Na+ Nernst potential of 55+mV. Voltage gated K+ channels also open as a response to depolarization but they only do so after the opening of the Na+ channels allowing a relatively large amount of K+ to leave the axon. As the voltage gated K+ channels open, the voltage gated Na+ channels now close preventing additional Na+ from entering the axon. So much positive charged K+ leaves the axon under these conditions that the membrane potential temporarily becomes hyperpolarized at a ...
DataMed is a prototype biomedical data search engine. Its goal is to discover data sets across data repositories or data aggregators. In the future it will allow searching outside these boundaries. DataMed supports the NIH-endorsed FAIR principles of Findability, Accessibility, Interoperability and Reusability of datasets with current functionality assisting in finding datasets and providing access information about them.
Cells are surrounded by a plasma membrane, which defines their extent and acts as a barrier between the cells and their external environment, for example interstitial fluid or blood plasma. The membrane, as a result of its lipid bilayer structure and specific membrane proteins, is selectively permeable (the hydrophobic interior prevents the passage of both large polar molecules and ions) and therefore will only allow certain species through. This selective permeability allows asymmetric concentrations of ions to exist between the intra- and extracellular fluids. These differences can be chemical or electrical (i.e. the difference in charge between the inside and outside). Most cells maintain a membrane potential of around 80mV relative to the surrounding fluid. The membrane potential is negative because usually cells have a net negative charge due to leakiness of potassium channels and the large size of negatively charged macromolecules such as proteins and RNA. In animal cells, passive ion ...
The FLIPR® Membrane Potential Assay Kits deliver homogenous fluorescence-based formulations for observation of real-time membrane potential changes associated with ion channel activation and ion transporter proteins. Each homogeneous assay kit utilizes a proprietary indicator dye and quencher combination to maximize ce
I agree that this is correct in the classical limit. However in the complete planck law is derived by assuming that the probability that a single mode is in a state of energy E=nhν (a state of n photons) is given by a Boltzmann distribution. Hence, the derivation does not consider any limit ...
TY - JOUR. T1 - Membrane potential resonance frequency directly influences network frequency through electrical coupling. AU - Chen, Yinbo. AU - Li, Xinping. AU - Rotstein, Horacio G.. AU - Nadim, Farzan. N1 - Funding Information: Support for this work was provided by the National Institute of Mental Health (R01-MH060605; to F. Nadim), National Institute of Neurological Disorders and Stroke (R01-NS083319; to F. Nadim), and National Science Foundation (DMS1313861; to H. G. Rotstein).. PY - 2016/10. Y1 - 2016/10. N2 - Oscillatory networks often include neurons with membrane potential resonance, exhibiting a peak in the voltage amplitude as a function of current input at a nonzero (resonance) frequency (fres). Although fres has been correlated to the network frequency (fnet) in a variety of systems, a causal relationship between the two has not been established. We examine the hypothesis that combinations of biophysical parameters that shift fres, without changing other attributes of the impedance ...
Other articles where Membrane potential is discussed: nervous system: The neuronal membrane: …neurons this potential, called the membrane potential, is between −60 and −75 millivolts (mV; or thousandths of a volt; the minus sign indicates that the inner surface is negative). When the inside of the plasma membrane has a negative charge compared to the outside, the neuron is said to be…
TY - JOUR. T1 - Low doses of ethanol have Ca2+ ionophore-like effects on apical membrane potential of in vitro Necturus antrum. AU - Rutten, Michael. AU - Moore, C. D.. PY - 1991. Y1 - 1991. N2 - The effects of low doses of luminal ethanol on the amiloride-sensitive apical membrane potential of Necturus antral mucosa were studied using conventional microelectrode techniques. Luminal ethanol (0.250-4.0% vol/vol) caused a dose-dependent hyperpolarization of the apical membrane potential (V(mc)), an increase in transepithelial resistance (R(t)) and resistance ratio (R(a)/R(b)), and a decrease in transepithelial potential (V(ms)). Luminal amiloride (100 μM) to 4% ethanol-treated antra did not cause any additional hyperpolarization of V(mc). Compared with luminal 2% ethanol-Ringer, an equivalent osmotic mannitol solution depolarized V(mc) and basolateral potential (V(cs)), decreased R(t) and R(a)/R(b), and increased V(ms). A single dose of 0.50% ethanol attenuated the effects of a second 2% ethanol ...
Several physiological mechanisms allow sensory information to be propagated in neuronal networks. According to the conventional view of signal processing, graded changes of membrane potential at the dendrite are converted into a sequence of spikes. However, in many sensory receptors and several types of mostly invertebrate neurons, graded potential changes have a direct impact on the cells output signals. The visual system of the blowfly Calliphora vicina is a good model system to study synaptic transmission in vivo during sensory stimulation. We recorded extracellularly from an identified motion-sensitive neuron while simultaneously measuring and controlling the membrane potential of individual elements of its presynaptic input ensemble. The membrane potential in the terminals of the presynaptic neuron is composed of two components, graded membrane potential changes and action potentials. To dissociate the roles of action potentials and graded potential changes in synaptic transmission we used ...
TY - JOUR. T1 - Label-free imaging of membrane potential using membrane electromotility. AU - Oh, Seungeun. AU - Fang-Yen, Christopher. AU - Choi, Wonshik. AU - Yaqoob, Zahid. AU - Fu, Dan. AU - Park, Yongkeun. AU - Dassari, Ramachandra R.. AU - Feld, Michael S.. PY - 2012/7/3. Y1 - 2012/7/3. N2 - Electrical activity may cause observable changes in a cells structure in the absence of exogenous reporter molecules. In this work, we report a low-coherence interferometric microscopy technique that can detect an optical signal correlated with the membrane potential changes in individual mammalian cells without exogenous labels. By measuring milliradian-scale phase shifts in the transmitted light, we can detect changes in the cells membrane potential. We find that the observed optical signals are due to membrane electromotility, which causes the cells to deform in response to the membrane potential changes. We demonstrate wide-field imaging of the propagation of electrical stimuli in ...
A Ba(2+)-sensitive K(+) current was studied in neurons of the suprachiasmatic nucleus (SCN) using the whole cell patch-clamp technique in acutely prepared brain slices. This Ba(2+)-sensitive K(+) current was found in approximately 90% of the SCN neurons and was uniformly distributed across the SCN. Current-clamp studies revealed that Ba(2+) (500 microM) reversibly depolarized the membrane potential by 6.7 +/- 1.3 mV (n = 22) and concomitantly Ba(2+) induced an increase in the spontaneous firing rate of 0.8 +/- 0.2 Hz (n = 12). The Ba(2+)-evoked depolarizations did not depend on firing activity or spike dependent synaptic transmission. No significant day/night difference in the hyperpolarizing contribution to the resting membrane potential of the present Ba(2+)-sensitive current was observed. Voltage-clamp experiments showed that Ba(2+) (500 microM) reduced a fast-activating, voltage-dependent K(+) current. This current was activated at levels below firing threshold and exhibited outward ...
Membrane potential oscillations can be induced in molluscan neurones under a variety of artificial conditions. In the so-called burster neurones oscillations are generated even in isolated cells. A likely mechanism for bursting involves the following ionic currents: 1. A transient inward current carried by Na+ and Ca2+. This current is responsible for the upstroke of the action potentials. 2. A delayed outward current carried by K+. This current is voltage-sensitive and is responsible for the downstroke of the action potential during the early part of the burst. It becomes progressively inactivated during the burst. Its amplitude depends on the intracellular pH. 3. A rapidly developing outward current carried by K+ which is inactivated at potentials close to action potential threshold. This current tends to hold the membrane in the hyperpolarized state and is involved in spacing the action potentials. 4. A prolonged inward current which may not inactivate. It is probably carried by both Na+ ...
The effect has been studied of various media, hormones and of amino acids on the membrane potential of rat hepatoma cells in culture measured by microelectrode impalement. Cells in Eagles minimal essential medium plus 5% serum had a value which varied daily from about 5-8 mV, inside negative. The membrane potential of rat hepatocytes was measured to be 8.7 ± 0.2mV, inside negative. The membrane potential of the hepatoma cells was decreased by insulin and increased by glucagon. Membrane potential was unaffected by change of medium to Hanks or Earles balanced salt solutions or deprivation of serum. It was, however, reduced in cells in phosphate-buffered saline and by reduction of pH. The former effect was shown to be due to the higher [Na+] of phosphat-buffered saline as opposed to the other media. Addition of alanine, glycine, serine, proline and methylaminoisobutyrate all reduced membrane potential by 2-3 mV. Smaller decreases were seen with methionine, leucine and phenylalanine, but none ...
Membrane potential plays a crucial role in many important physiological processes in bacteria. It is a component of the proton-motive force and is used to power various membrane-embedded complexes, including ATP synthase, the flagellar motor, and various small-molecule transport systems (1-5). Membrane potential has also been shown to be critical for bacterial cell division, proliferation, and signaling, and recent studies have begun to elucidate the mechanisms by which bacterial membrane potential is regulated (6-10).. Bacterial membrane potential also plays a critical role in antibiotic susceptibility, highlighting the value in identifying membrane potential-altering compounds in the quest to combat multidrug-resistant pathogens (5, 11-13). For example, carbonyl cyanide 3-chlorophenylhydrazone (CCCP), a well-known proton ionophore, increases Enterobacteriaceae susceptibility to polymyxins, while others have shown that hyperpolarizing conditions, such as those with the addition of alanine and ...
TY - THES. T1 - Studies on membrane properties of cholesterol and 3-beta modified sterol analogs. AU - Lönnfors, Max. PY - 2014. Y1 - 2014. N2 - Cholesterol (Chol) is an important lipid in cellular membranes functioning both as a membrane fluidity regulator, permeability regulator and co-factor for some membrane proteins, e.g. G-protein coupled receptors. It also participates in the formation of signaling platforms and gives the membrane more mechanical strenght to prevent osmotic lysis of the cell. The sterol structure is very conserved and already minor structural modifications can completely abolish its membrane functions. The right interaction with adjacent lipids and the preference of certain lipid structures over others are also key factors in determining the membrane properties of cholesterol. Because of the many important properties of cholesterol it is of value to understand the forces and structural properties that govern the membrane behavior of this sterol. In this thesis we have ...
Using sorting protocol based on a simple staining method for mitochondrial membrane potential we were able to isolate subclones from an established monoclonal antibody production cell line with significantly altered physiological properties. The subclone sorted for lower mitochondrial membrane potential had a faster growth rate, attained higher final cell concentrations in batch cultures, had lower glucose and glutamine uptake and lactate production rates as well as a higher specific production rate. The subclone sorted for high mitochondrial membrane potential on the other hand had a lower growth rate and final cell count, increased glucose and glutamine consumption and lactate production rates. These subclones can now be used for genomic or proteomic analysis of properties that characterise a cell line with efficient or inefficient metabolism. In addition, the method described is a valuable tool for cell line development and optimisation, offering the possibility to isolate subclones with both ...
Inwardly rectifying K+ currents were studied in cut muscle fibres from frogs using the Vaseline-gap voltage-clamp method. Both faces of the membrane were exposed to 120 mM-K+ methylsulphate solution. At small negative potentials, -10 and -21 mV, the current noise spectrum, after subtraction of a control spectrum at the zero current potential, could be fitted by a Lorentzian spectral component, usually with an additional 1/f component, where f is the frequency. At more negative potentials the 1/f component predominated. The zero frequency amplitude of the Lorentzian averaged 2.6 X 10(-24) A2 Hz-1 at -10 mV and 4.6 X 10(-24) A2 Hz-1 at -21 mV, with a mean half-power frequency, fc, of 34 Hz and 45 Hz, respectively. The time constant of the K+ current activation upon hyperpolarization agrees with that calculated from fc, and the Lorentzian disappears upon replacement of external K+ by tetraethylammonium (TEA+) or Rb+. Thus, the Lorentzian component appears to be ascribable to fluctuations ...
Similar to the NMDAR, AMPARs are excitatory ionotropic glutamatergic receptors and consist of four subunits. AMPARs mediate the majority of fast excitatory synaptic transmission in the CNS and are mostly composed of two GluA1 and two GluA2 subunits. In contrast to NMDARs, there is no obligatory subunit and there is a larger variability in receptor composition (108). Importantly, the presence of GluA2 determines crucial properties of the receptor: RNA editing of the Q/R site of the GluA2 subunit modifies the pore region of the receptor so that AMPARs containing GluA2 are impermeable to Ca2+ and show a linear current-voltage relationship (109). In contrast, AMPARs without GluA2 are Ca2+ permeable, have a larger single-channel conductance, and are inwardly rectifying, as intracellular polyamines can block the channel pore at positive membrane potentials (109, 110). Patients with anti-AMPAR encephalitis harbor antibodies against either GluA1 or GluA2 subunits, resulting in a reduction of surface ...
TY - JOUR. T1 - Calcium sparklets regulate local and global calcium in murine arterial smooth muscle. AU - Amberg, Gregory C.. AU - Navedo, Manuel F.. AU - Nieves-cintrón, Madeline. AU - Molkentin, Jeffery D.. AU - Santana, Luis F.. PY - 2007/2/15. Y1 - 2007/2/15. N2 - In arterial smooth muscle, protein kinase Cα (PKCα) coerces discrete clusters of L-type Ca2+ channels to operate in a high open probability mode, resulting in subcellular domains of nearly continual Ca2+ influx called persistent Ca2+ sparklets. Our previous work suggested that steady-state Ca2+ entry into arterial myocytes, and thus global [Ca2+]i, is regulated by Ca2+ influx through clusters of L-type Ca2+ channels operating in this persistently active mode in addition to openings of solitary channels functioning in a low-activity mode. Here, we provide the first direct evidence supporting this Ca2+ sparklet model of Ca2+ influx at a physiological membrane potential and external Ca2+ concentration. In support of this ...
Excitotoxicity due to glutamate occurs as part of the ischemic cascade and is associated with stroke[1] and diseases like amyotrophic lateral sclerosis, lathyrism, autism, some forms of mental retardation, and Alzheimers disease.[8][1] Glutamic acid has been implicated in epileptic seizures. Microinjection of glutamic acid into neurons produces spontaneous depolarisations around one second apart, and this firing pattern is similar to what is known as paroxysmal depolarizing shift in epileptic attacks. This change in the resting membrane potential at seizure foci could cause spontaneous opening of voltage-activated calcium channels, leading to glutamic acid release and further depolarization. Experimental techniques to detect glutamate in intact cells include using a genetically-engineered nanosensor.[9] The sensor is a fusion of a glutamate-binding protein and two fluorescent proteins. When glutamate binds, the fluorescence of the sensor under ultraviolet light changes by resonance between the ...
Biological cells express intracellular biomolecular information to the extracellular environment as various physical responses. We show a novel computational approach to estimate intracellular biomolecular pathways from growth cone electrophysiological responses. Previously, it was shown that cGMP signaling regulates membrane potential (MP) shifts that control the growth cone turning direction during neuronal development. We present here an integrated deterministic mathematical model and Bayesian reversed-engineering framework that enables estimation of the molecular signaling pathway from electrical recordings and considers both the system uncertainty and cell-to-cell variability. Our computational method selects the most plausible molecular pathway from multiple candidates while satisfying model simplicity and considering all possible parameter ranges. The model quantitatively reproduces MP shifts depending on cGMP levels and MP variability potential in different experimental conditions. ...
Patch clamp method was used to search for, and characterize ion channel activity which may participate in cation influx in human myeloid K562 cells. In cell-attached, outside-out and whole-cell experiments two types of voltage-insensitive Na-permeable channels were identified with different selectivities for monovalent cations, referred to as channels of high (HS) and low (LS) selectivity. The unitary conductance was similar for both channel types being 12 pS (145 mmol/l Na, 23 degrees C). The relative permeability PNa/PK estimated from the extrapolated reversal potential values were 10 and 3 for HS and LS channels, respectively. Both HS and LS channels were found to be impermeable to bivalent cations (Ca2+ or Ba2+). The activity of HS and LS channels displayed a tendency to increase with depolarization. Both channel types were not blocked by tetrodotoxin and were insensitive to amiloride in the concentration range of up to 100 mumol/l. At higher concentrations (0.1-2 mmol/l), amiloride ...
Gas - Gas - Boltzmann equation: The simple mean free path description of gas transport coefficients accounts for the major observed phenomena, but it is quantitatively unsatisfactory with respect to two major points: the values of numerical constants such as a, a′, a″, and a12 and the description of the molecular collisions that define a mean free path. Indeed, collisions remain a somewhat vague concept except when they are considered to take place between molecules modeled as hard spheres. Improvement has required a different, somewhat indirect, and more mathematical approach through a quantity called the velocity distribution function. This function describes how molecular velocities are distributed
Baseline toxicity of a selection of industrial chemicals and pharmaceuticals is determined experimentally with a new in vitro test system (Kinspec) using membrane vesicles isolated from a photosynthetic bacterium, Rhodobacter sphaeroides. This test system is selective and more sensitive than other mechanistic test systems for baseline toxicity. The only concomitantly determined mechanism is uncoupling, which can be distinguished from baseline toxicity by pH-dependent measurements. Because the tests system contains only the target site for baseline toxicants, the biological membrane, effective target site concentrations can be directly related to observed effects by combining the in vitro test with membrane-water partition experiments. No differences were found between the effective membrane concentrations of nonpolar and polar compounds, confirming the earlier hypothesis that differences in lethal body burdens are primarily caused by unequal distribution of the compounds between target and ...
Neurons in the central nervous system, and in the cortex in particular, are subject to a barrage of pulses from their presynaptic populations. These synaptic pulses are mediated by conductance changes and therefore lead to increases or decreases of the neuronal membrane potential with amplitudes that are dependent on the voltage: synaptic noise is multiplicative. The statistics of the membrane potential are of experimental interest because the measurement of a single subthreshold voltage can be used to probe the activity occurring across the presynaptic population. Though the interpulse interval is not always significantly smaller than the characteristic decay time of the pulses, and so the fluctuations have the nature of shot noise, the majority of results available in the literature have been calculated in the diffusion limit, which is valid for high-rate pulses. Here the effects that multiplicative conductance noise and shot noise have on the voltage fluctuations are examined. It is shown that both
Rien, D., Kern, R., & Kurtz, R. (2011). Synaptic transmission of graded membrane potential changes and spikes between identified visual interneurons. European Journal of Neuroscience, 34(5), 705-716. doi:10.1111/j.1460-9568.2011.07801. ...
If we shift our focus over to the cardiac myocyte in particular well remember that potassium and sodium are the major role players. Potassium is concentrated intracellularly and sodium is hanging out extracellularly. The good old Sodium-Potassium pump is keeping the peace, the peace being a negative resting membrane potential. The concentration gradient across this membrane plays an important role in maintaining this action potential. As the extracellular potassium concentration increases, the resting membrane potential gets less negative. This is important because the resting membrane potential (the flat part before the action potential gets going) directly impacts the number of voltage-gated sodium channels available to generate the action potential. Fewer sodium channels means slower impulse conduction and prolonged membrane depolarization. How do we see this? QRS widening, P wave prolongation, PR widening ...
In midbrain dopamine neurons in vitro, N-methyl-D-aspartate (NMDA) evokes oscillation of membrane potential and burst firing which are dependent on a ouabain-sensitive sodium pump. In the present study, we investigated the ionic dependence and pharmacological modulation of NMDA-mediated currents which might be important in burst firing. By use of patch pipettes to record membrane currents in whole-cell voltage clamps, we found that NMDA (10 microM) evoked inward currents that were significantly reduced in a low extracellular concentration of Na+ (25 mM), but not when extracellular Ca+2 was decreased from 2.5 to 0.5 mM. The current-voltage relationship for subtracted NMDA currents showed a prominent region of negative slope conductance which was absent when the slice was perfused with solution containing zero Mg++. 7-Chlorokynurenic acid, an antagonist at the nonstrychnine-sensitive glycine binding site, produced a concentration-dependent reduction in amplitude of excitatory postsynaptic currents ...
TY - JOUR. T1 - Kv2.1 channels play opposing roles in regulating membrane potential, Ca2+ channel function, and myogenic tone in arterial smooth muscle. AU - ODwyer, Samantha C.. AU - Palacio, Stephanie. AU - Matsumoto, Collin. AU - Guarina, Laura. AU - Klug, Nicholas R.. AU - Tajada, Sendoa. AU - Rosati, Barbara. AU - McKinnon, David. AU - Trimmer, James S.. AU - Santana, L. Fernando. PY - 2020/2/18. Y1 - 2020/2/18. N2 - The accepted role of the protein Kv2.1 in arterial smooth muscle cells is to form K+ channels in the sarcolemma. Opening of Kv2.1 channels causes membrane hyperpolarization, which decreases the activity of L-type CaV1.2 channels, lowering intracellular Ca2+ ([Ca2+]i) and causing smooth muscle relaxation. A limitation of this model is that it is based exclusively on data from male arterial myocytes. Here, we used a combination of electrophysiology as well as imaging approaches to investigate the role of Kv2.1 channels in male and female arterial myocytes. We confirmed that ...
This experiment deals about understanding the nature of ionic current using a voltage-current plot usually called V-I plot. It also investigates the role of linearity in ionic current behavior.
1. Action potentials recorded in the soma of R15 neurones in the abdominal ganglia of Aplysia juliana were not suppressed by selective inhibition of either Na or Ca conductance alone. It was necessary to block both conductances to suppress action potentials. 2. Membrane currents generated by step depolarizations of the soma consisted of early transient and delayed steady-state currents. The early transient current could have one or two components depending on the activating depolarization. 3. The early more rapid component had a reversal potential at +54 mV and the reversal potential changed with extracellular Na concentration in accord with the Nernst equation. It was blocked by substitution of impermeant cations for Na, by TTX and by internal injections of Zn. It was concluded that this component was normally a Na current. 4. The later slower component of the transient current had a reversal potential at about +65 mV and the reversal potential changed with extracellular Ca concentration is accord with
Purified JC-1 Mitochondrial Membrane Potential Assay Kit from Creative Biomart. JC-1 Mitochondrial Membrane Potential Assay Kit can be used for research.
Thank you, Dr. Ferber- but let me clarify my question- Were making current clamp recordings, and injecting square current pulses whilst in current clamp. Our amplifier seems to turn off capacitance/series resistance compensation in current clamp mode, though Im not so sure. In our preparation, a strong inward rectifying current is expected to be seen in medium spiny neurons by applying hyperpolarizing pulses. Weve been applying 20 pA steps from 0 to -1nA (the maximum current injection possible for our amplifier), yet we do not see any inward rectification. Inward rectification is a defining characteristic of medium spiny neurons. These cells have been labelled iontophoretically with neurobiotin, and we see that they are indeed medium spiny neurons. Weve checked our intracellular and ACSF ionic concentrations against what others are using, and find no great difference. The cell fires what appear to be normal action potentials with depolarizing pulses in current clamp. Im thinking that ...
TY - JOUR. T1 - Self-Sustained Oscillations of Membrane Potential in DOPH-Millipore Membranes. AU - Toko, Kiyoshi. AU - Ryu, Kouichi. AU - Ezaki, Shu. AU - Yamafuji, Kaoru. PY - 1982. Y1 - 1982. N2 - Self-sustained oscillations of membrane potential in an artificial model membrane, where dioleyl phosphate (DOPH) is infiltrated into pores of a Millipore filter, are investigated both experimentally and theoretically. Spike-like selfoscillations with an extremely long period of about one hour were observed for membranes with large adsorbed amounts of DOPH in the absence of external forces such as electric current and pressure gradient. On the basis of a previously-presented model that DOPH molecules make transitions among three phases composed of oil droplets, spherical micelles and multi- or bilayer leaflets, the occurrence of self-oscillations is explained well by taking account of an accumulation and a release of salt in a pore of the filter.. AB - Self-sustained oscillations of membrane ...
MitoPedia ,abbr=mtMP, Δψ [V] ,description=The mitochondrial membrane potential, mtMP, is the electric part of the protonmotive [[force]], Δp,sub>H+,/sub>. Δψ = Δp,sub>H+,/sub> - Δµ,sub>H+,/sub> / F mtMP or Δψ is the potential difference across the inner mitochondrial (mt) membrane, expressed in the electric unit of volt [V]. Electric force of the mitochondrial membrane potential is the electric energy change per motive electron or per electron moved across the transmembrane potential difference, with the number of motive electrons expressed in the unit coulomb [C]. ,info=[[Mitchell 1961 Nature]], [[Gnaiger 2014 Preface MiP2014]] }} Communicated by [[Gnaiger E]] 2012-10-05, edited 2016-02-06, 2017-09-05. :::: The chemical part of the protonmotive force, µ,sub>H+,/sub> / F stems from the difference of pH across the mt-membrane. It contains a factor that bridges the gap between the electric force [J/C] and the chemical force [J/mol]. This ...
We have discussed simple concentration gradients-differential concentrations of a substance across a space or a membrane-but in living systems, gradients are more complex. Because ions move into and out of cells and because cells contain proteins that do not move across the membrane and are mostly negatively charged, there is also an electrical gradient, a difference of charge, across the plasma membrane. The interior of living cells is electrically negative with respect to the extracellular fluid in which they are bathed, and at the same time, cells have higher concentrations of potassium (K+) and lower concentrations of sodium (Na+) than does the extracellular fluid. So in a living cell, the concentration gradient of Na+ tends to drive it into the cell, and the electrical gradient of Na+ (a positive ion) also tends to drive it inward to the negatively charged interior. The situation is more complex, however, for other elements such as potassium. The electrical gradient of K+, a positive ion, ...
Dear Sir / Madam,. I cant patch on cardiomyocytes to record action potentials at 37 degree C using a perforated patch technique. I tried many things, but failed.. Following the suggestions from this forum, I patched the cell at room temperature. After cell got gigaohm sealed, I turned on the temperature controller. At this moment, I found that it was very easy to loss the cell, because of an electric shock?. So late on, I made a little bit changes and did as followings: (1) I turned on the temperature controller but set temperature at 22oC; (2) patched the cell to get gigaohm seal; (3) waited for about 40 minutes to allow Gramicidin to perforate the cell membrane; (4) switched voltage clmap mode to current clamp mode to see if action potential could be induced or not and (5) if the action potential could be seen, then turned the wheel of temperature controller to increase the bath temperature to 37oC at once. But I found that the cell still losed ...
View Notes - 4 Influence of Passive Membrane Properties on Neural Signals - lecture slides from IPHY 4720 at Colorado. Signaling Within & Between Nerve Cells Influence of Passive Membrane
The fundamental cellular parameters of cell volume (Vc) and resting membrane potential (Em) profoundly influence cellular, tissue, organ and whole-body physiology. Earlier work has identified a wide range of mechanisms that maintain, regulate, or otherwise influence the values of each parameter individually. However, both Vc and Em change during normal activity in skeletal muscle, and their resting values are interdependent. New quantitative theoretical and experimental techniques were developed to permit an investigation of the interrelationships between Vc and Em, in order to study the determination, maintenance and short-term regulation of each parameter in skeletal muscle. Thus a cellular model was developed that permitted accurate theoretical analysis of the influences upon both Vc and Em of the diverse mechanisms known to maintain and regulate Vc, and a laser-confocal microscope technique was developed for the dynamic measurement of Vc in viable whole-muscle preparations. These new ...
If you are a society or association member and require assistance with obtaining online access instructions please contact our Journal Customer Services team ...
BioAssay record AID 767820 submitted by ChEMBL: Inhibition of human ERG expressed in HEK293 cells assessed as membrane depolarization at 3 uM by patch-clamp method.
Due to commercial and government interest in devices capable of functioning in high-power, high-frequency space applications, radiation tolerant AlGaNGaN devices have been under study in recent years. Passivation of the AlGaN surface by Si3N4 prevents electron trapping and enhances the 2DEG, but it also increases gate leakage currents, which can lead to device failure. This study sought information about current leakage mechanisms by introducing displacement damage close to the Si3N4AlGaN interface. The effects of irradiation damage around the Si3N4AlGaN interface on irradiation-induced leakage current were investigated for three thicknesses of a Si3N4 passivation layer in addition to an unpassivated sample. AlGaNGaN samples were irradiated at room temperature with 15-50keV nitrogen ions. Hall measurements determined mobility and 2DEG carrier density. C-V measurements provided insight into charge location and effects of the band structure. Pre-irradiation measurements were compared to the irradiation
Na Channel Has a quick onset and quickly turns off: inactivating channel. K is the opposite with slow onset and slow turn off: noninactivating channel. This difference is caused by differences in the two proteins. The Na channel has two gates: the activation gate and the inactivation gate. The activation gate is sensitive to the potential. When the activation gate is closed the inactivation gate is closed. When the inside of the cell is depolarized, the activation gate quickly opens. The inactivation gate, composed of negative proteins, slowly is repelled by the positive change in the intracellular environment, so it closes the channel by find its way into the pore of the channel.. K Channel. Has a single gate activated by the membrane potential, so it will stay open all the time the membrane has a certain potential. Na and K Conductances Nas conductance is characterized by a rapid onset and a rapid offset. Ks conductance is characterized by a slow onset and a slow offset. Membrane potential ...
Ion channel conductance can be influenced by electrostatic effects originating from fixed surface charges that are remote from the selectivity filter. To explore whether surface charges contribute to the conductance properties of Kir2.1 channels, unitary conductance was measured in cell-attached recordings of Chinese hamster ovary (CHO) cells transfected with Kir2.1 channels over a range of K + activities (4.6-293.5 mM) using single-channel measurements as well as nonstationary fluctuation analysis for low K + activities. K + ion concentrations were shown to equilibrate across the cell membrane in our studies using the voltage-sensitive dye DiBAC 4 (5). The dependence of γ on the K + activity (a K ) was fit well by a modified Langmuir binding isotherm, with a nonzero intercept as a K approaches 0 mM, suggesting electrostatic surface charge effects. Following the addition of 100 mM N-methyl-D-glucamine (NMG + ), a nonpermeant, nonblocking cation or following pretreatment with 50 mM ...
Action potentials are used in neurons to conduct signals along the axon and occur in electrically excitable cells like neurons and cardiac muscle cells. The action potentials travel in a wave along the membrane causing the voltage sensitive channels to open to allow influx of Na+ thereby causing the conduction of the signal along the axon. The resting membrane potential of cells including neurons is -70mv. An action potential is generated by a change in the membrane potential from -70mv to +40mv when voltage gated ion channels open altering membrane permeability to Na+ and K+. ...
Complex mixtures, commonly encountered in metabolomics and food analytics, are now routinely measured by nuclear magnetic resonance (NMR) spectroscopy. Since many samples must be measured, one-dimensional proton (1D 1H) spectroscopy is the experiment of choice. A common challenge in complex mixture 1H NMR sp Lab on a Chip Recent Open Access Articles
Laboratory of Engineering Thermodynamics - University of Kaiserslautern . Laboratory of Engineering Thermodynamics (LTD) University of Kaiserslautern
We introduce and validate new computational tools that enable efficient generation and simulation of models containing stochastic ion channels distributed across dendritic and axonal membranes. Comparison of five morphologically distinct neuronal cell types reveals that when all simulated neurons contain identical densities of stochastic ion channels, the amplitude of stochastic membrane potential fluctuations differs between cell types and depends on sub-cellular location. ... The code is downloadable and more information is available at ,a href=,,/a ...
Some cells or organelles have the same membrane potential throughout; neurons generally have different potentials at different ... Biological membrane potentials. The value of the signal is an electric potential (voltage). The domain is more difficult to ...
Unstable Membrane PotentialsEdit. Many cells have resting membrane potentials that are unstable. It is usually due to ion ... Slow wave potentialsEdit. Slow wave potential are unstable resting membrane potentials that continuously cycle through ... Pacemaker potentialsEdit. Pacemaker potentials are unstable cell membrane potentials that reach depolarization threshold with ... When the membrane potential reaches depolarization threshold an action potential (AP) is fired, excitation-contraction coupling ...
... and injury potential (potential difference between injured and intact membrane/epithelium). The injury potential was, in fact, ... Oviedo, N. J; Nicolas, C. L; Adams, D. S; Levin, M (2008). "Live Imaging of Planarian Membrane Potential Using DiBAC4(3)". Cold ... Levin, M; Thorlin, T; Robinson, K. R; Nogi, T; Mercola, M (2002). "Asymmetries in H+/K+-ATPase and cell membrane potentials ... In non-excitable cells, the resting potential across the plasma membrane (Vmem) of individual cells propagate across distances ...
Pidot, A. L.; Diamond, J. M. (1964). "Streaming Potentials in a Biological Membrane". Nature. 201 (4920): 701-702. doi:10.1038/ ... Cooke, I. M.; Diamond, J. M.; Grinnell, A. D.; Hagiwara, S.; Sakata, H. (1968). "Suppression of the action potential in nerve ... Clausen, C.; Machen, T. E.; Diamond, J. M. (1982). "Changes in the Cell Membranes of the Bullfrog Gastric Mucosa with Acid ... Loo, D. D.; Lewis, S. A.; Ifshin, M. S.; Diamond, J. M. (1983). "Turnover, membrane insertion, and degradation of sodium ...
Araya R, Jiang J, Eisenthal KB, Yuste R (November 2006). "The spine neck filters membrane potentials". Proceedings of the ... The number of ion channels on the post-synaptic membrane affects the strength of the synapse. Research suggests that the ... These processes, and by extension the number of receptors on the membrane, can be altered by synaptic activity. Experiments ... Also, these signals recruit additional receptors into the post-synaptic membrane, stimulating the production of a modified ...
Araya, R.; Jiang, J.; Eisenthal, K. B.; Yuste, R. (2006). "The spine neck filters membrane potentials". Proceedings of the ... Araya, R.; Nikolenko, V.; Eisenthal, K. B.; Yuste, R. (2007). "Sodium channels amplify spine potentials". Proceedings of the ... "Label-free probe of HIV-1 TAT peptide binding to mimetic membranes". Proceedings of the National Academy of Sciences. 111 (35 ...
July 2018). "Mitochondrial membrane potential". Analytical Biochemistry. 552: 50-59. doi:10.1016/j.ab.2017.07.009. PMC 5792320 ... This proton gradient is largely but not exclusively responsible for the mitochondrial membrane potential (ΔΨM). It allows ATP ... The use of different quinones is due to slightly altered redox potentials. These changes in redox potential are caused by ... These levels correspond to successively more positive redox potentials, or to successively decreased potential differences ...
2. Membrane-potentials, apparent resistances, and mechanisms. Mechanism of the light peak and other responses originating at ... 1. Membrane-potentials, apparent resistances, and mechanisms". Journal of Neuroscience 9 (6) 1968-1976 (1989) Cited 42 times. ... "Effects of dopamine on the chick retinal-pigment epithelium - membrane-potentials and light-evoked responses". Investigative ... "Light-evoked modulation of basolateral membrane Cl− conductance in chick retinal-pigment epithelium - the light peak and fast ...
"Light-sensitive membrane potentials in onion guard cells". Nature. 270 (5634): 270-271. Bibcode:1977Natur.270..270Z. doi: ... Hepler postulates that the extracellular influx of calcium is not governed by the plasma membrane but by changes in the ion- ... Wolniak, S. M., P. K. Hepler, and W. T. Jackson (1980). "Detection of the membrane-calcium distribution during mitosis in ... Hepler, P. K. (1980). "Membranes in the mitotic apparatus of barley cells". Journal of Cell Biology. 86 (2): 490-499. doi: ...
See the Membrane potential article. Free radical reactions are redox reactions that occur as a part of homeostasis and killing ... The electrode potential of each half-reaction is also known as its reduction potential E0 red, or potential when the half- ... Each half-reaction has a standard electrode potential (E0 cell), which is equal to the potential difference or voltage at ... the potential difference is: E0 cell = E0 cathode - E0 anode However, the potential of the reaction at the anode is sometimes ...
Dielectric relaxation Dielectrophoresis Membrane potential. ... of cellular compartments and their surrounding membranes. ...
It also makes possible the measurement of spatial and temporal variations in membrane potential along the surface of single ... Many physiological processes are accompanied by changes in cell membrane potential which can be detected with voltage sensitive ... Cohen LB, Salzberg BM (1978). Optical Measurement of Membrane Potential. Reviews of Physiology, Biochemistry and Pharmacology. ... Measurements may indicate the site of action potential origin, and measurements of action potential velocity and direction may ...
Goldman DE (September 1943). "Potential, Impedance, and Rectification in Membranes". The Journal of General Physiology. 27 (1 ...
"Imaging membrane potential in dendritic spines". PNAS. 103 (3): 786-790. Bibcode:2006PNAS..103..786N. doi:10.1073/pnas. ... It has also been used to prove that backpropagating action potentials invade dendritic spines without voltage attenuation, ...
"Mitochondrial Membrane Potential in Living Cells". Annual Review of Cell Biology. Lan Bo Chen, Andrew Murray, Rosalind A. Segal ... Chen, Lan Bo (1988-11-01). "Mitochondrial Membrane Potential in Living Cells". Annual Review of Cell Biology. 4 (1): 155-181. ...
Bernstein was also the first to introduce the Nernst equation for resting potential across the membrane. In 1907, Louis ... Bernstein's hypothesis about the action potential was confirmed by Cole and Howard Curtis, who showed that membrane conductance ... Goldman DE (September 1943). "Potential, Impedance, and Rectification in Membranes". The Journal of General Physiology. 27 (1 ... Bernstein advanced the hypothesis that the action potential resulted from a change in the permeability of the axonal membrane ...
Rhoades, Rodney A.; Bell, David R. (2012). "Plasma membrane. membrane transport, and resting membrane potential". Medical ... where the substances travel through the cell passing through both the apical membrane and basolateral membrane 2. Renal ... This transport can either be absorption, transport from lumen (apical membrane surface) to blood, or secretion, transport from ... the cell membrane is a hydrophobic environment and will not allow the passive diffusion of charged, hydrophilic, or zwitterion ...
When the membrane potential from the dendrites exceeds the resting membrane potential, a pulse is generated by the neuron cell ... If the stimulus drives the membrane to a positive potential, it is an excitatory neuron; and if it drives the resting potential ... When the cumulative postsynaptic potential exceeds the resting potential, an action potential is generated by the cell body or ... action potential). The resting potential for potassium-sodium channels in a neuron is about -65 millivolts. The membrane model ...
Ahmad, N.; Masood, A. K.; Owais, M. (15 November 2001). "Fusogenic potential of prokaryotic membrane lipids". European Journal ... he demonstrated the fusogenic attributes of sperm plasma membrane lipids, and established the prophylactic potential of ... "Fusogenic potential of sperm membrane lipids: Nature's wisdom to accomplish targeted gene delivery". FEBS Letters. 580 (9): ... Correlation with membrane-membrane fusion events. Biochim Biophys Acta. 2005 May 20;1669(2):170-81. Younus H, Owais M, Rao DN, ...
"Mitochondrial membrane potential in living cells."Annu Rev Cell Biol. 4 (1988) 155-181 Darzynkiewicz Z, Traganos F, Staiano- ... This use relies on the fact that rhodamine 123 accumulates in membranes in a manner which is dependent on membrane polarization ... Rhodamine fluorescence can also be used as a measure of membrane polarization in live cell assays both within mitochondria and ... "Mitochondrial inner membrane electrophysiology assessed by rhodamine-123 transport and fluorescence" Annals of Biomedical ...
Double sucrose gap, however, can measure the membrane potential and resistance. Another limitation is that membrane potentials ... The recording of membrane potentials in the superior cervical ganglion was made simple with the sucrose-gap method as it allows ... A pair of agar-bridged Ag-AgCl electrodes are placed in the test and KCl chambers to record the changes in membrane potential. ... When used with proper electronics, the double sucrose gap can be used to voltage clamp the membrane potential of the nerve or ...
... makes this inactivation happen at less depolarized membrane potentials. This means that lacosamide only affects ... In a study conducted to assess the teratogenic potential of AEDs in the zebrafish embryo, the teratogenicity index of ... Inactivation only occurs in neurons firing action potentials; this means that drugs that modulate fast inactivation selectively ... This inactivation prevents the channel from opening, helping end the action potential. Many antiepileptic drugs, like ...
Other interesting uses of fluorescent proteins in the literature include using FPs as sensors of neuron membrane potential, ... "Genetically encoded fluorescent sensors of membrane potential". Brain Cell Biology. 36 (1-4): 53-67. doi:10.1007/s11068-008- ... Due to the potential for widespread usage and the evolving needs of researchers, many different mutants of GFP have been ... For example, mGFP often refers to a GFP with an N-terminal palmitoylation that causes the GFP to bind to cell membranes. ...
Effect of intralysosomal pH and membrane potential". The Journal of Biological Chemistry. 262 (3): 1244-53. PMID 2948955. ... The proton motive force (pmf) across the lysosomal membrane is generated by a V-type ATPase which hydrolyzes cytoplasmic ATP to ... Removal of the C-terminal GYDQL lysosomal sorting motif causes cystinosin to migrate to the plasma membrane with the ...
Schirmer EC, Florens L, Guan T, Yates JR 3rd, Gerace L (Sep 2003). "Nuclear membrane proteins with potential disease links ... 2006). "NDC1: a crucial membrane-integral nucleoporin of metazoan nuclear pore complexes" (PDF). J. Cell Biol. 173 (4): 509-19 ...
Schirmer EC, Florens L, Guan T, Yates JR, Gerace L (Sep 2003). "Nuclear membrane proteins with potential disease links found by ... Veitia RA, Ottolenghi C, Bissery MC, Fellous A (Oct 1999). "A novel human gene, encoding a potential membrane protein conserved ...
... glycoprotein mediating the fusion of the virus and its host cell membranes. The fusion mechanism is also studied as a potential ... The fusion event is when the virus membrane and the host cell membrane fuse together allowing a virus to enter. It does this by ... Types of entry are: Membrane fusion or Hemifusion state: The cell membrane is punctured and made to further connect with the ... "Coronavirus membrane fusion mechanism offers a potential target for antiviral development". Antiviral Research. 178: 104792. ...
Involvement in mitochondrial membrane potential and cell death". The Journal of Biological Chemistry. 277 (36): 33249-57. doi: ... Involvement in mitochondrial membrane potential and cell death". The Journal of Biological Chemistry. 277 (36): 33249-57. doi: ... It may play important roles in the regulation of the mitochondrial membrane potential and in protection against oxidant-induced ... The encoded protein may play important roles in the regulation of the mitochondrial membrane potential and in protection ...
This causes a hyperpolarization of its membrane potential. This hyperpolarizing effect could lead to increased uptake of ...
Potentiators reduce the zeta potential of RBC membranes. Common potentiators include low ionic strength solution (LISS), ... RBCs have a net negative charge called zeta potential which causes them to have a natural repulsion for one another. ... IgM mediated activation of classical complement pathway and Membrane attack complex, MAC) (A memory device to remember that the ...
Though successful in predicting the timing and qualitative features of the action potential, it nevertheless failed to predict ... from membrane currents, proteins, and chemical coupling to network oscillations, columnar and topographic architecture, and ... Huxley developed the voltage clamp and created the first biophysical model of the action potential. Hubel & Wiesel discovered ... "A quantitative description of membrane current and its application to conduction and excitation in nerve". J. Physiol. 117 (4 ...
Implement usage limitations when the Fish and Wildlife service express a potential adverse effect on a particular species based ... includes any device which contacts intact mucous membranes but which does not ordinarily penetrate the blood barrier or ... The amendments required the EPA to assess potential risks the pesticides posed to humans, the environment, and wildlife and ... of 1910 set standards for chemical quality and provided consumers protection but did not address the growing issue of potential ...
There are several special leak test methods available to test the integrity of an LNG vessel's membrane cargo tanks.[104] ... Some scientists and local residents have raised concerns about the potential effect of Poland's LNG infrastructure on marine ...
VEGF-B treatment of hepatoma carcinoma cells can cause α-catenin to move from its normal location on the membrane into the ... Lab studies have also implicated potential therapeutic targets for future clinical studies. VEGFR-1 and EMT mediators may be ... thus enhancing the invasive potential of LNCaP cells (human prostate cancer cells). As a result, it is possible that the EMT ...
The first potential issue is the unwanted aggregation of particles, but this can occur in any centrifugation. The second ... The ribosomes, membranes and Golgi complexes can be separated by another technique called density gradient centrifugation. ... This method is commonly used to separate organelles and membranes found in cells. Organelles generally differ from each other ... Ultracentrifuges can also be used in the study of membrane fractionation. This occurs because ultracentrifuges can reach ...
EBOV is thought to infect humans through contact with mucous membranes or skin breaks.[54] After infection, endothelial cells ( ... The potential for widespread infections in countries with medical systems capable of observing correct medical isolation ... Virions bud off from the cell, gaining their envelopes from the cellular membrane from which they bud. The mature progeny ... It has the potential to be weaponised for use in biological warfare,[226][227] and was investigated by Biopreparat for such use ...
... which allows neurons to intrinsically fire action potentials at sub-threshold membrane potentials. Studies have shown that the ... Unlike the fast and transient sodium current, the persistent sodium current (INaP) is activated at very low membrane potentials ... In CS pacemakers, NE increases only the amplitude of the depolarizing drive potential and the number of action potentials ... L-type calcium channels are known to increase the frequency of action potentials in some neurons, which might be the reason ...
regulation of membrane potential. • nervous system process. • synaptic transmission, GABAergic. • postsynaptic potential. ... membrane. • synapse. • integral component of plasma membrane. • chloride channel complex. • cell junction. • plasma membrane. • ... integral component of membrane. • GABA-A receptor complex. • postsynaptic membrane. • ... integral component of postsynaptic specialization membrane. • dendrite membrane. • neuron projection. • postsynapse. Biological ...
Giltay EJ, Gooren LJ (2009). "Potential side effects of androgen deprivation treatment in sex offenders". The Journal of the ... membrane. *Aphthous stomatitis. *oral candidiasis. *lichen planus. *leukoplakia. *pemphigus vulgaris. *mucous membrane ... Rolfe HM (December 2014). "A review of nicotinamide: treatment of skin diseases and potential side effects". Journal of ... due to greater potential side effects.[8][17] Early and aggressive treatment of acne is advocated by some in the medical ...
A potential use for rituximab was identified by two Norwegian doctors who were treating people who had cancer with rituximab; ... Although the function of CD20 is unknown, it may play a role in Ca2+ influx across plasma membranes, maintaining intracellular ... The CD20 proteins are sticking out of the cell membrane, and rituximab, the Y-shaped antibody, is binding to the CD20 proteins. ...
Potential risk factors[edit]. Temperature and heat exposure[edit]. The temperature and heat levels of the body are directly ... Synthetic membrane earphone[edit]. Modern technology seeks to minimize or prevent listener fatigue entirely. Blockage of the ... A film of medical-grade polymer (ePTFE) is stretched over a hole, essentially acting as a membrane to help absorb pressure ... Researchers at Asius Technologies have designed a synthetic membrane to take the brunt of the pounding in earphones away from ...
The German Type 214 submarine employs advanced polymer electrolyte membrane fuel cells that assist in delivering it comparable ... hydrodynamic capabilities into a potential SEA 1000 design.[22] Advantages in such a deal between the nations include the ... although with the caveat that a change in government in either nation would compromise any potential deal for construction, or ... Australian submarines have to transit long distances to reach some of their potential patrol areas. This requirement for range ...
It explores potential surfaces with modified antennules; once it has found a potentially suitable spot, it attaches head-first ... In some barnacles, the cement glands are fixed to a long, muscular stalk, but in most they are part of a flat membrane or ... Similarly, they have no gills, absorbing oxygen from the water through their limbs and the inner membrane of their carapaces. ...
Another potential symptom is a metallic, acidic, salty or bitter taste in the mouth. The pseudomembranous type rarely causes ... That is, oral candidiasis is a mycosis (yeast/fungal infection) of Candida species on the mucous membranes of the mouth. ... It may precede the formation of a pseudomembrane, be left when the membrane is removed, or arise without prior pseudomembranes ... Disruption to any of these local and systemic host defense mechanisms constitutes a potential susceptibility to oral ...
... is a key first responder to most noxious/extreme stimuli (stressors), i.e., those with a potential to compromise ... Its receptor - the neurokinin type 1 - is distributed over cytoplasmic and nuclear membranes of many cell types (neurons, glia ... Hesketh PJ (Jul 2001). "Potential role of the NK1 receptor antagonists in chemotherapy-induced nausea and vomiting". Supportive ... Łazarczyk M, Matyja E, Lipkowski A (2007). "Substance P and its receptors -- a potential target for novel medicines in ...
Although the function of CD20 is unknown, it may play a role in Ca2+ influx across plasma membranes, maintaining intracellular ... This potential use was investigated after improvements in chronic fatigue syndrome was seen in two cancer patients treated with ... The CD20 proteins are sticking out of the cell membrane, and rituximab, the Y-shaped antibody, is binding to the CD20 proteins. ...
... which is mostly suspended from the roof of the mantle cavity by numerous membranes. The tract consists of a crop, where the ... This form of locomotion allows these octopuses to move quickly away from a potential predator without being recognised.[76] A ...
To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential. ... Stacks of membrane-enclosed disks are unattached to cell membrane directly Disks are attached to outer membrane ... Thus, the random opening or closing of sodium channels will not affect the membrane potential of the cell; only the closing of ... This change in the cell's membrane potential causes voltage-gated calcium channels to close. This leads to a decrease in the ...
While cerclage is generally a safe procedure, there are a number of potential complications that may arise during or after ... These include: risks associated with regional or general anesthesia premature labor premature rupture of membranes infection of ...
Presumably in stress conditions (such as sulfur starvation) it may act as a valve for low-potential electrons and maintain ... have a common outer membrane. Basa 16:31, 19 January 2007 (UTC) ...
Other solutions entail an incubator with an impermeable membrane that has a specific mix of gases (air with 5% CO2 is typical) ... which is the summation of action potentials over all electrodes in an MEA. This analysis yielded the conclusion that, in their ... This chamber serves as a non-humidified incubator that is enclosed by a fluorinated ethylene propylene (FEP) membrane that is ... quieted networks have little capacity for plasticity due to a diminished ability to create action potentials. A different and ...
Because of their double-membrane envelope, Borrelia bacteria are often mistakenly described as Gram negative despite the ... White matter disease may have a greater potential for recovery than gray matter disease, perhaps because the neuronal loss is ... Spirochetes are surrounded by peptidoglycan and flagella, along with an outer membrane similar to Gram-negative bacteria. ... Ixodes larvae and nymphs typically wait for potential hosts ("quest") on leaves or grasses close to the ground with forelegs ...
... s have potential roles in relaxation of the myometrium via non-genomic, androgen receptor-independent pathways, ... Lang F, Alevizopoulos K, Stournaras C (2013). "Targeting membrane androgen receptors in tumors". Expert Opin. Ther. Targets. 17 ... Androgens have also been found to signal through membrane androgen receptors, which are distinct from the classical nuclear ...
The cell membrane potential created by potassium and sodium ions allows the cell to generate an action potential-a "spike" of ... known as the membrane potential. The balance between potassium and sodium is maintained by ion transporter proteins in the cell ... Standard electrode potential (E°(M+→M0); V)[71]. −3.04. −2.71. −2.93. −2.98. −3.03. ? ... One of the very few properties of the alkali metals that does not display a very smooth trend is their reduction potentials: ...
Human brains are surrounded by a system of connective tissue membranes called meninges that separate the brain from the skull. ... This has been under investigation since 2010 in a Phase I/II clinical trial for the potential treatment of recurrent high-grade ...
Lang F, Alevizopoulos K, Stournaras C (2013). "Targeting membrane androgen receptors in tumors". Expert Opin. Ther. Targets. 17 ... Martinez-Ariza G, Hulme C (2015). "Recent advances in allosteric androgen receptor inhibitors for the potential treatment of ... AR antagonists may not bind to or block membrane androgen receptors (mARs), which are distinct from the classical nuclear AR.[ ... which is under development as a topical medication for the potential treatment of acne.[105] SARDs like dimethylcurcumin differ ...
As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry ... Hansen, D.M.; Donlan, C.J.; Griffiths, C.J.; Campbell, K.J. (April 2010). "Ecological history and latent conservation potential ... Hicks, J; Farmer, CG (1999). "Gas Exchange Potential in Reptilian Lungs: Implications for the Dinosaur-Avian Connection". ... warning potential predators they are venomous.[121] A number of non-venomous North American snake species have colorful ...
The technology has potential applications in cancer diagnosis,[14] neuroscience, gene expression analysis,[15] and companion ... The tissue sample is chemically treated in order to make the cell membranes permeable to the fluorescently tagged ...
Libet found that the unconscious brain activity of the readiness potential leading up to subjects' movements began ... hard problem of consciousness involves determining how physiological processes such as ions flowing across the nerve membrane ... since the readiness potential does not invariably lead to an action. In Freedom Evolves, Daniel Dennett argues that a no-free- ... Readiness-Potential)". Brain. 106 (3): 623-42. doi:10.1093/brain/106.3.623. PMID 6640273.. ...
Inside the endosome, the decreased pH induces the fusion of the endosomal membrane with the virus envelope. The capsid enters ... Exposure for even a short time is enough for a potential mosquito bite. Long-sleeved clothing, long pants, and socks are useful ... Receptor binding, as well as membrane fusion, are catalyzed by the protein E, which changes its conformation at low pH, causing ... Yellow fever has been researched by several countries as a potential biological weapon.[105] ...
The neuronal membrane: …neurons this potential, called the membrane potential, is between −60 and −75 millivolts (mV; or ... thousandths of a volt; the minus sign indicates that the inner surface is negative). When the inside of the plasma membrane has ... Other articles where Membrane potential is discussed: nervous system: ... In nervous system: The neuronal membrane. …neurons this potential, called the membrane potential, is between −60 and −75 ...
... potential is depolarized to a critical potential (Ecrit), a self-generating action potential follows, leading to muscle ... Phase 0, the upstroke, is associated with a sudden increase in membrane permeability to Na+. Phases 1, 2, and 3 result from ... changes in membrane permeability and conductance to Na+, K+, and Ca2+. ... Other articles where Critical membrane potential is discussed: muscle: The frequency of contraction: … ...
Membrane potential definition at, a free online dictionary with pronunciation, synonyms and translation. Look it ... membrane potential. n.. *The potential inside a cell membrane measured relative to the fluid just outside; it is negative under ...
Membrane potential and gentamicin uptake in Staphylococcus aureus. S M Mates, E S Eisenberg, L J Mandel, L Patel, H R Kaback, M ... Membrane potential and gentamicin uptake in Staphylococcus aureus. S M Mates, E S Eisenberg, L J Mandel, L Patel, H R Kaback, M ... Membrane potential and gentamicin uptake in Staphylococcus aureus. S M Mates, E S Eisenberg, L J Mandel, L Patel, H R Kaback, ... At pH 5.0, the electrical potential (delta psi, interior negative) across the plasma membrane of Staphylococcus aureus exhibits ...
Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the ... the resting membrane potential is merely the membrane potential that results from the membrane permeabilities that predominate ... This term is used for the membrane potential of non-excitable cells, but also for the membrane potential of excitable cells in ... Because voltage-gated ion channels are controlled by the membrane potential, while the membrane potential itself is influenced ...
Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the ... the resting membrane potential is merely the membrane potential that results from the membrane permeabilities that predominate ... Changes to membrane potential during developmentEdit. A neurons resting membrane potential actually changes during the ... The term "membrane potential" may refer to one of three kinds of membrane potential:[1] ...
Rather, it is the *tendency* of movements to occur (which depends on changing permeabilities) that governs membrane potential. ... no net ionic flux occurs and the membrane potential is stable. The NE is dependent on two things, the permeability of the ... the ionic flux required to swing a membrane from neutral to the NE potential is so slight that the original internal and ... is responsible for causing the resting membrane potential. Just a small leak (relatively) is sufficient to establish the ...
Membrane potential is the voltage that exists across the membrane of a cell. Its particularly important in nerve cells, since ... A membrane potential is the voltage which exists across the membrane of a cell. It is also known as a transmembrane potential, ... where the cell membrane goes through a process called depolarization. After the action potential, the membrane potential ... Membrane potentials arise because cell membranes do not allow sodium and potassium ions to pass freely in and out of cells and ...
Membrane potential dynamics underlying context-dependent sensory responses in the hippocampus. *Xinyu Zhao1, ... Zhao, X., Wang, Y., Spruston, N. et al. Membrane potential dynamics underlying context-dependent sensory responses in the ...
If youre seeing this message, it means were having trouble loading external resources on our website.. If youre behind a web filter, please make sure that the domains * and * are unblocked. ...
Subthreshold membrane potential oscillations are membrane oscillations that do not directly trigger an action potential since ... these subthreshold membrane potential oscillations do not trigger action potentials, since the firing of an action potential is ... Neurons produce action potentials when their membrane potential increases past a critical threshold. In order for neurons to ... Subthreshold membrane potential oscillations do not create an action potential; however, neurons do experience bursting when ...
For the membrane potential channel (1), multiply the values by 0.1 to remove the instrumentation gain. This gives the membrane ... Squid Giant Axon Membrane Potential. This data set, its source, and the methods used to generate it, are described in ... The membrane potential and stimulus current are given for a total of 170 trials across 8 different axons. ... potential in volts.. *For the stimulus current channel (2), apply the physical unit conversion, 1V = 5uA/cm2 to get the ...
Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors, Whole-cell Patch-clamp ... Membrane Potentials, Synaptic Responses, Neuronal Circuitry, Neuromodulation and Muscle Histology Using the Crayfish: Student ... Surface Potential Measurement of Bacteria Using Kelvin Probe Force Microscopy, The Preparation of Oblique Spinal Cord Slices ... Modeling Biological Membranes with Circuit Boards and Measuring Electrical Signals in Axons: Student Laboratory Exercises, ...
Membrane-SPINE: A Biochemical Tool to Identify Protein-protein Interactions of Membrane Proteins In Vivo, Functional Magnetic ... Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae ... Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution, Three- ... Targeted Plasma Membrane Delivery of a Hydrophobic Cargo Encapsulated in a Liquid Crystal Nanoparticle Carrier, Preparation ...
De novo gene origination from nonfunctional DNA sequences was long assumed to be implausible. However, recent studies have shown that large fractions of genomic noncoding DNA are transcribed and translated, potentially generating new genes. Experimental validation of this process so far has been limited to comparative genomics, in vitro selections, or partial randomizations. Here, we describe selection of novel... ...
Organ of Corti Potentials and the Motion of the Basilar Membrane. Anders Fridberger, Jacques Boutet de Monvel, Jiefu Zheng, ... Organ of Corti Potentials and the Motion of the Basilar Membrane. Anders Fridberger, Jacques Boutet de Monvel, Jiefu Zheng, ... Organ of Corti Potentials and the Motion of the Basilar Membrane Message Subject (Your Name) has forwarded a page to you from ... Organ of Corti Potentials and the Motion of the Basilar Membrane. Anders Fridberger, Jacques Boutet de Monvel, Jiefu Zheng, ...
These extracellular potentials are not filtered by the membrane. To test this theory, both electric potentials inside the organ ... Organ of Corti Potentials and the Motion of the Basilar Membrane. Anders Fridberger, Jacques Boutet de Monvel, Jiefu Zheng, ... Organ of Corti Potentials and the Motion of the Basilar Membrane. Anders Fridberger, Jacques Boutet de Monvel, Jiefu Zheng, ... Organ of Corti Potentials and the Motion of the Basilar Membrane Message Subject (Your Name) has forwarded a page to you from ...
Early events are represented by ion flux unbalances that eventually lead to plasma transmembrane potential (Vm) variations. ... I. Membrane potentials, intracellular calcium variations, oral secretions, and regurgitate components. Plant Physiol 134:1752- ... Zebelo S.A., Maffei M.E. (2012) Signal Transduction in Plant-Insect Interactions: From Membrane Potential Variations to ... Signal Transduction in Plant-Insect Interactions: From Membrane Potential Variations to Metabolomics. ...
Because persister cells have a lower membrane potential than normal cells, we hypothesize that persister cells have reduced ... This is a ~4 times increase compared to treatment without membrane depotentiation which only led to 22.0 ± 3.3% killing. ...
... Chi-Won Choi,1,2 ... "Potential Usefulness of Streptococcus pneumoniae Extracellular Membrane Vesicles as Antibacterial Vaccines," Journal of ...
It was strongly speculated that the membrane potential origin could lie primarily in the ion adsorption on the membrane (or ... The adsorption theory attributes the membrane potential generation to the ion adsorption onto the membrane (or separator) ... variation of membrane permeability to ion in accordance with ion species results in the variation of the membrane potential. ... It might be necessary to reconsider the origin of membrane potential which has been so far believed explicable by the GHK ...
Video created by Peking University for the course Advanced Neurobiology I. Lets switch to the electrical properties of the neuron. 2000+ courses from schools like Stanford and Yale - no application required. Build career skills in data ...
The FLIPR® Membrane Potential Assay Kits provide a fast, simple and reliable fluorescence-based assay for detecting changes in ... voltage across the cell membrane mediated by ion channel to evaluate target or off-target effects based on the application. ...
... Oh, Seungeun. ... "Label-Free Imaging of Membrane Potential Using Membrane Electromotility." Biophysical Journal 103, no. 1 (July 2012): 11-18. © ... membrane potential. We find that the observed optical signals are due to membrane electromotility, which causes the cells to ... Membrane electromotility-induced cell deformation may be useful as a reporter of electrical activity.. en_US. ...
The formation of vesicles at the plasma membrane is mediated by the G protein dynamin that catalyzes the final fission step, ... Taken together, our results suggest a versatile role for pacsin-1 in sculpting cellular membranes that is likely dependent both ... Theoretical free energy calculations suggest bimodality of the protein-membrane system as a possible source for the different ... In addition, liposomes prepared with different methods yield distinct membrane deformation morphologies of BAR domain proteins ...
... Adam M Gilmore, Australian National University, Canberra City, ... Plásek J and Sigler K (1996) Slow fluorescent indicators of membrane potential: a survey of different approaches to probe ... Gilmore, Adam M(Apr 2001) Cell Membranes: Intracellular pH and Electrochemical Potential. In: eLS. John Wiley & Sons Ltd, ... Cell Membranes , Biomolecular Interactions , Cellular Transport , Bioenergetics , Proteins: Structure, Function, Metabolism , ...
Dendritic attenuation of synaptic potentials and currents: the role of passive membrane properties.. Spruston N1, Jaffe DB, ... Voltage-gated channels might influence the measurement of passive membrane properties and, reciprocally, passive membrane ... The pattern of activation of these synaptic inputs determines if the neuron will fire an action potential at any given point in ... The authors review recent data from patch-clamp recordings that provide new estimates of the passive membrane properties of ...
... an impaired ETC is not able to generate a mitochondrial membrane potential. ρ° cells are able to sustain mitochondrial membrane ... G) Mitochondrial membrane potential assessed by TMRE (50nM) staining and corrected by CCCP (50 μM) of DN-POLG-GFP/BFP and DN- ... TCA Cycle and Mitochondrial Membrane Potential Are Necessary for Diverse Biological Functions.. Martínez-Reyes I1, Diebold LP1 ... Mitochondrial membrane potential dependent ROS is essential for hypoxic stabilization of HIF-1α protein and cell proliferation ...
Wafer-scale mitochondrial membrane potential assays Tae-Sun Lim,a Antonio Davila Jr,bc Katayoun Zand,a Douglas C. Wallacec and ... Wafer-scale mitochondrial membrane potential assays T. Lim, A. Davila Jr, K. Zand, D. C. Wallace and P. J. Burke, Lab Chip, ... Membrane potential changes of isolated mitochondria from various well-established cell lines such as human HeLa cell line ( ... structural durability and reproducibility while increasing the sensitivity to changes in mitochondrial membrane potential by an ...
... then we can get the ones described of this which is the potential. And in our case, it would be a membrane potential, is equal ... its the relationship to the concentration and then the membrane potential. Or the potential, lets put it this way. But if you ... So if the resting membrane potential in our pretty cell, if you still remember, and robust cell thats still surviving all this ... Here will be the membrane potential. Then one can derive this equation. ...
  • Action potentials are generated by the activation of certain voltage-gated ion channels. (
  • Because voltage-gated ion channels are controlled by the membrane potential, while the membrane potential itself is influenced by these same ion channels, feedback loops that allow for complex temporal dynamics arise, including oscillations and regenerative events such as action potentials. (
  • Neurons produce action potentials when their membrane potential increases past a critical threshold. (
  • All in all, although the subthreshold membrane potential oscillations do not produce action potentials by themselves, through summation, they are able to still impact action potential outcomes. (
  • Neurons display, beyond synaptic and action potentials, rhythmic subthreshold membrane potential oscillations (a particular type of neural oscillations). (
  • This current is responsible for the upstroke of the action potentials. (
  • This current tends to hold the membrane in the hyperpolarized state and is involved in spacing the action potentials. (
  • The membrane potential in the terminals of the presynaptic neuron is composed of two components, graded membrane potential changes and action potentials. (
  • To dissociate the roles of action potentials and graded potential changes in synaptic transmission we used voltage-clamp-controlled current-clamp techniques to suppress the graded membrane potential changes without affecting action potentials. (
  • Our results indicate that both the graded potential and the action potentials of the presynaptic neuron have an impact on the spiking characteristics of the postsynaptic neuron. (
  • In excitable cells, a sufficiently large depolarization can evoke an action potential, in which the membrane potential changes rapidly and significantly for a short time (on the order of 1 to 100 milliseconds), often reversing its polarity. (
  • During nerve impulse transmission , what is known as an action potential occurs, where the cell membrane goes through a process called depolarization. (
  • Once the threshold value is reached, an action potential is produced, causing a rapid increase of Na+ enters the cell with more Na+ channels along the membrane opening, resulting in a rapid depolarization of the cell. (
  • The fluorescence of DiBAC4(3) is enhanced with membrane depolarization. (
  • Both methylmercury (MeHg) and inorganic divalent mercury (Hg++) alter the flux of ions and small molecules across nerve terminal membranes by mechanisms that may involve membrane depolarization. (
  • To investigate the relationship between hyposmotic membrane stretch and muscarinic receptor agonist-induced depolarization of membrane potential in antral gastric circular myocytes of guinea-pig. (
  • 0.05), and atropine (1 μmol/L) inhibited the depolarization of the membrane potential. (
  • 0.05) and hyposmotic membrane stretch potentiated the depolarization. (
  • Hyposmotic membrane stretch potentiated muscarinic receptor agonist-induced depolarization of membrane potential, which is related to hyposmotic membrane stretch-induced increase of muscarinic current. (
  • The mitochondrion (a) is shown with an enlarged view of the inner membrane and associated respiratory energy‐transducing components. (
  • The symbols n and p represent the negative and positive sides of the inner membrane, respectively. (
  • Domestic dog sperm are labeled with a cationic fluorescent probe, DiOC 2 (3), that reports the MP across the inner membrane of the mitochondria located in the sperm's midpiece. (
  • In this study, we report that the mitochondrial inner membrane rhomboid protease presenilin-associated rhomboid-like protein (PARL) mediates cleavage of PINK1 dependent on mitochondrial membrane potential. (
  • However, PINK1 has an apparent N-terminal mitochondrial import sequence predicted to mediate import through the TIM23 complex either to the matrix or spanning the inner membrane. (
  • Membrane potential changes of isolated mitochondria from various well-established cell lines such as human HeLa cell line (Heb7A), human osteosarcoma cell line (143b) and mouse skeletal muscle tissue were investigated and compared. (
  • It's important to note that the membrane potential of mitochondria is much higher than 60mV- IIRC it's closer to 220 mV. (
  • Edit: I guess I didn't actually answer your question- the answer is that the membrane resting potential is set by how efficiently mitochondria convert the energy of burning sucrose into a proton gradient. (
  • DiBAC dyes are excluded from mitochondria because of their overall negative charge, making them superior to carbocyanines for measuring plasma membrane potentials. (
  • A distinctive feature of the early stages of apoptosis is the disruption of the mitochondria, including changes in membrane and redox potential. (
  • When mitochondrial membrane potential is dissipated, PINK1 accumulates as a 63-kD full-length form on the outer mitochondrial membrane, where it can recruit Parkin to impaired mitochondria. (
  • Fluorescence, absorbance, and binding of a mitochondrial membrane potential-sensitive probe, rhodamine 800 (rhod800), were measured in isolated rat mitochondria, hepatocytes, cardiomyocytes, and hearts in the presence or absence of mitochondrial uncouplers. (
  • All animal cells are surrounded by a membrane composed of a lipid bilayer with proteins embedded in it. (
  • Transmembrane proteins, also known as ion transporter or ion pump proteins, actively push ions across the membrane and establish concentration gradients across the membrane, and ion channels allow ions to move across the membrane down those concentration gradients. (
  • Orange rectangles - membrane-impermeable anions (these arise from a variety of sources including proteins). (
  • Therefore, Dallos and Evans ( 1995a ) proposed that extracellular potential changes within the organ of Corti could drive cellular motor proteins. (
  • To comprehensively identify integral membrane proteins of the nuclear envelope (NE), we prepared separately NEs and organelles known to cofractionate with them from liver. (
  • In addition to all 13 known NE integral proteins, 67 uncharacterized open reading frames with predicted membrane-spanning regions were identified. (
  • Two integral membrane proteins are localized to the NPC in mammals ( 3 ), but the number specific to the inner nuclear membrane is unknown: It includes at least 11 proteins and their splice variants ( 1 ). (
  • No proteins specific to the outer membrane have yet been described. (
  • Avoiding prior separation by polyacrylamide gel electrophoresis removes its chemical and physical biases and the need to solubilize membrane proteins for the analysis ( 6 ). (
  • Slow-response dyes function by entering depolarized cells and binding to proteins or membranes. (
  • The slow-response potential-sensitive probe, DiBAC 4 (3) enters depolarized cells where it binds to intracellular proteins or membrane and exhibits enhanced fluorescence and a red spectral shift. (
  • The membrane, as a result of its lipid bilayer structure and specific membrane proteins, is selectively permeable (the hydrophobic interior prevents the passage of both large polar molecules and ions) and therefore will only allow certain species through. (
  • The membrane potential is negative because usually cells have a net negative charge due to leakiness of potassium channels and the large size of negatively charged macromolecules such as proteins and RNA. (
  • Our data challenge the generally accepted view that Kv2.1 proteins regulate arterial smooth muscle function by regulating their membrane potential. (
  • These results suggest that PKG and PI3K are involved in degranulation, possibly through phosphorylation of target membrane SNAP receptor proteins and their binding proteins. (
  • SNAREs, which were initially identified in neuronal cells for their function in membrane fusion ( 5 ), include vesicular SNAREs such as vesicle-associated membrane proteins, target membrane SNAREs (t-SNAREs) such as syntaxins, and the Sec1/Munc18 family of proteins that serve as binding partners of t-SNAREs. (
  • Mining the proteome of cell envelopes and native membrane vesicles revealed 533 and 168 common proteins, respectively, in analyzed GC strains FA1090, F62, MS11, and 1291. (
  • Among those proteins that displayed similar abundance in four GC strains, 34 were found in both cell envelopes and membrane vesicles fractions. (
  • In addition, we selected for initial characterization six predicted outer membrane proteins with unknown function, which were identified as ubiquitous in the cell envelopes derived from examined GC isolates. (
  • The study examined electrophysiological properties and ionic bases of subthreshold oscillation of the membrane potential in 104 magnocellular neurons of rats, using intracellular recording techniques. (
  • One of the more significant features of this system of producing membrane potential oscillations is that the frequency of the bursts depends on the rate at which the intracellular ionized calcium returns to its resting level. (
  • Intracellular heterogeneity in mitochondrial membrane potentials revealed by a J-aggregate-forming lipophilic cation JC-1. (
  • Membrane potential oscillations were studied in slices of rat somatosensory cortex maintained in vitro, using intracellular recordings from cells in layers 2/3 and 5. (
  • Among other roles, the cell potential acts as a reservoir for metabolic energy, which cells use to drive the transport of solute molecules across the membrane, to communicate with other cells and to trigger intracellular events. (
  • These two functions are highlighted by differences in the regulation of membrane potential, intracellular Ca 2+ , and myogenic tone between males and females. (
  • Opening of Kv2.1 channels causes membrane hyperpolarization, which decreases the activity of L-type Ca V 1.2 channels, lowering intracellular Ca 2+ ([Ca 2+ ] i ) and causing smooth muscle relaxation. (
  • Here, we studied the fluoride-induced apoptosis in H9c2 cells and determined the underlying molecular mechanisms including the cell viability, intracellular reactive oxygen species (ROS) level, the changes of mitochondrial membrane potential, and the cell apoptosis. (
  • In summary, these data suggested that NaF-induced H9c2 cell apoptosis is mediated by direct increased intracellular ROS and downregulated [mitochondrial membrane potential]. (
  • Dendritic attenuation of synaptic potentials and currents: the role of passive membrane properties. (
  • Whenever currents cross membranes separating aqueous solutions, differences in transport numbers of the major permeant ions give rise to local concentration changes of these ions adjacent to the membranes, which will result in various electrical and osmotic effects. (
  • It is shown that in the case of large currents and potentials the analytical solution predictions will underestimate the magnitudes and rates of onset of the voltage responses. (
  • It has already been shown from studies of the fluctuations that can be detected in very small membrane currents, that alamethicin forms transient pores of some 0.6 nm in diameter and that, for small inorganic ions, these are poorly selective. (
  • for a review see Fettiplace, 2009 ) of the transduction channels, and the resulting receptor currents and receptor potentials, have been extensively studied in several hair cell types. (
  • Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. (
  • transmembrane potential-covered in this page. (
  • in many cases the term "membrane potential" refers to the transmembrane potential. (
  • Virtually all eukaryotic cells (including cells from animals, plants, and fungi) maintain a non-zero transmembrane potential, [ citation needed ] usually with a negative voltage in the cell interior as compared to the cell exterior ranging from -40 mV to -80 mV. (
  • It is also known as a transmembrane potential, and it is particularly important in nerve cells, or neurons. (
  • Early events are represented by ion flux unbalances that eventually lead to plasma transmembrane potential (Vm) variations. (
  • diastolic potential the transmembrane potential of the cell during electrical diastole . (
  • Membrane potential (or transmembrane potential or transmembrane potential difference or transmembrane potential gradient ), is the electrical potential difference across a cell 's plasma membrane . (
  • Hence every organelle and every membranous compartment (such as a synthetic vesicle ) has a transmembrane potential (although the size of this potential may be zero). (
  • A graded potential is a gradient of transmembrane potential difference. (
  • This voltage is the resting cell potential , also sometimes called the transmembrane potential of the resting cell. (
  • Most insects have the ability to alter their cold tolerance in response to temporal temperature fluctuations, and recent studies have shown that insect cold tolerance is closely tied to the ability to maintain transmembrane ion-gradients that are important for the maintenance of cell membrane potential (V m ). (
  • Phases 1, 2, and 3 result from changes in membrane permeability and conductance to Na + , K + , and Ca 2+ . (
  • This voltage is established when the membrane has permeability to one or more ions. (
  • Essentially, if you have a concentration gradient of a single ion between two sides of a semipermeable membrane that exhibits high permeability to that ion, you will get diffusion of that ion down its chemical gradient. (
  • The NE is dependent on two things, the permeability of the membrane to the ionic species and the initiating chemical gradient. (
  • Interestingly, with a high chemical gradient and high permeability, the ionic flux required to swing a membrane from neutral to the NE potential is so slight that the original internal and external concentrations can be taken as not having altered. (
  • The natural leak of the K from inside to outside following this (due to high permeability to K) is responsible for causing the resting membrane potential. (
  • The fundamental facet of the GHK equation lies in its consideration of permeability of membrane to ions, when the membrane serves as a separator for separating two electrolytic solutions. (
  • The GHK equation describes that: variation of membrane permeability to ion in accordance with ion species results in the variation of the membrane potential. (
  • It was strongly speculated that the membrane potential origin could lie primarily in the ion adsorption on the membrane (or separator) rather than the membrane permeability to ions. (
  • The GHK equation explains that membrane permeability varies in accordance with ion species in the aqueous solution, and it is one of fundamental factors determining how high potential is generated across the membrane. (
  • According to the GHK equation, the complex change of membrane permeability to the ions results in the complex cell membrane potential behavior. (
  • Hence, basically, membrane permeability is a dominant factor for cell membrane potential generation. (
  • As the RMP stabilizes, Cl- ions passively disperse based on the permeability and polarity of the plasma membrane. (
  • The dual effect of membrane potential on sodium conductance in the giant axon of Loligo. (
  • I understand that RMP is a result of other factors (channels, conductance, reversal potentials etc) and merely imposing a value to it might be meaningless. (
  • This article is concerned primarily with the mechanism of the potential-dependent conductance induced in artificial lipid membranes by the cyclic polypeptide antibiotic alamethicin. (
  • It is demonstrated that the sensitivity of the membrane conductance to the applied potential arises only to a slight extent from the current-voltage relations for the individual pores, and that the main effect stems from the influence of the potential on the frequency of opening of the pores. (
  • At isolated hair cells, the K channel blocker tetraethylammonium (TEA) is shown to block a fraction of total voltage-dependent K-conductance (IKD) that depends on TEA concentration but not on membrane potential ( V m ). (
  • I was not even satisfied with what my standard med school physiology texts taught me about membrane equilibria, so I had done some research then. (
  • Together, these findings underscore the concept that the cell envelope and membrane vesicles contain crucial, yet under-explored determinants of GC physiology, which may represent promising targets for designing new therapeutic interventions. (
  • In particular, mitochondrial membrane potential (MMP) was investigated as a predictor of a cell's likelihood to avoid apoptosis from freeze-induced stress. (
  • Villena J, Madrid A, Montenegro I, Werner E, Cuellar M, Espinoza L. Diterpenylhydroquinones from Natural ent -Labdanes Induce Apoptosis through Decreased Mitochondrial Membrane Potential. (
  • JC-1 Mitochondrial Membrane Potential Assay Mitochondrial membrane potential (MMP) is an important parameter of mitochondrial function that has been used as an indicator of cell apoptosis. (
  • The extract also induced a remarkable decrease in mitochondrial membrane potential ([DELTA][PSI]m) leading to apoptosis of cancer cells used. (
  • Antigenicity potential of demineralized freeze-dried bovine cortical bone membrane (DFDBCBM) was done with histology-based anticellularity evaluation, while cytotoxicity was analyzed using MTT Assay. (
  • We offer a range of Molecular Probes products specifically designed to assay mitochondrial membrane potential. (
  • JC-10 Mitochondrial Membrane Potential Assay is based upon JC-10 dye, which is a superior alternative to JC-1 dye due to its increased solubility. (
  • Cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, ultrastructural alterations were examined using inverse phase contrast microscopy and electron microscopy, mitochondrial membrane potential was measured using rhodamine 123 labeling and flow cytometry, and neurofilament light (NF-L) mRNA expression was detected by reverse transcription-polymerase chain reaction. (
  • Impedance and potential measurements have been made on a number of artificial membranes. (
  • Finally, second harmonic measurements of membrane potential reveal an attenuation of somatic voltages into the spine head, an attenuation directly proportional to neck length. (
  • The green fluorescent dye forms red fluorescent aggregates with increasing membrane potential, allowing ratiometric potential measurements. (
  • DiOC5(3) and DiOC6(3) are two of the most widely used carbocyanine dyes for membrane potential measurements. (
  • Tetramethylrhodamine ethyl ester (TMRE) and Tetramethylrhodamine methyl ester (TMRM) can be used for quantitative measurements of membrane potential and mitochondrial membrane potential. (
  • The dyes also undergo spectral shift with changes in membrane potential, allowing ratiometric measurements. (
  • The uncompensated positive charges outside the cell, and the uncompensated negative charges inside the cell, physically line up on the membrane surface and attract each other across the lipid bilayer . (
  • Furthermore, using DelPhi to assign different dielectric constants for different regions of the LPS membranes, it was investigated whether a single frame structure before MD simulations with appropriate dielectric constants for the lipid tails, inner, and the external leaflet regions, can deliver the same average electrostatic potential distribution as obtained from the MD-generated ensemble of structures. (
  • In membrane biophysics it is sometimes used interchangeably with cell potential, but is applicable to any lipid bilayer or membrane . (
  • From the properties of lipid membranes containing alamethicin in a wide variety of electrolytes, and from other evidence, it is concluded that the polypeptide reacts to the electric field more probably because it has a large dipole moment than because it binds ions. (
  • Membrane potentials arise because cell membranes do not allow sodium and potassium ions to pass freely in and out of cells and reach an equilibrium. (
  • Ion pumps in the membrane use energy to pump sodium ions out of the cell, while pumping potassium in. (
  • The action potential begins when a nerve stimulus arrives at the cell, opening special sodium channels in the cell membrane. (
  • Positively charged sodium ions pass into the cell, and the membrane potential changes, becoming less negative. (
  • When a point known as the action threshold is reached, many more sodium channels open and the inside of the cell membrane becomes positively charged, the reverse of normal. (
  • In order for neurons to reach threshold for action potential to fire, enough sodium (Na+) ions must enter the cell through voltage gated sodium channels through membrane and depolarize the cell. (
  • Due to unequal distributions mainly of potassium and sodium ions (the cell membrane being partially, but not equally, permeable to both) which in turn determines the relative movements of these ions down their respective diffusion gradients (potassium outwards and sodium inwards). (
  • The resulting membrane potential after opening many of these channels with a decreased extracellular concentration of sodium ions is -60 mV, with a decreased extracellular concentration of chloride ions is -50 mV, and with a decreased extracellular concentration of calcium ions is -50 mV. (
  • The sodium channel is opened with a decreased extracellular concentration of Na+ and the membrane potential goes to -60 mV (more negative). (
  • if one were to change the extracellular concentration of sodium why would the effect on the membrane potential not be as significant such as when the extracellular concentration of potassium is changed? (
  • Production of large unilamellar vesicles by a rapid extrusion procedure: characterization of size distribution, trapped volume and ability to maintain a membrane potential. (
  • Development activities at Applied Biomimetics Inc. focuses on incorporation of aquaporins in colloidal polymer vesicles and development of a coating platform using colloidal particles as membrane building blocks. (
  • SynaptoGreen™ and SynaptoRed™ nerve terminal probes (originally called FM® dyes) are membrane dyes used to trace endocytic vesicles. (
  • Despite the implied role of the GC cell envelope and membrane vesicles in colonization and infection of human tissues and cell lines, comprehensive studies have not been undertaken to elucidate their constituents. (
  • In this talk, I will discuss the performance of the membranes towards removal of natural organic matter such as tannic acid, and perfluoro-octanoic acid (PFOA) - a typical compound associated with degradation of fluorinated organics. (
  • The need was to find a way of controlling the architecture of membrane micro-structures in a predictable way so that the performance of the membranes can be predicted and controlled from the outset of designing the membranes," said Dr. Darrell Patterson, the director for the Centre for Advanced Separations Engineering at the University of Bath, and an author of the study. (
  • Slow potential changes in mammalian muscle fibres during prolonged hyperpolarization: Transport number effects and chloride depletion. (
  • Opening of Kv2.1 channels opposes vasoconstriction by inducing membrane hyperpolarization. (
  • TEA (10 mmol/L), a nonselective potassium channel blocker significantly inhibited hyposmotic membrane stretch-induced hyperpolarization. (
  • Many ions have a concentration gradient across the membrane, including potassium (K + ), which is at a high concentration inside and a low concentration outside the membrane. (
  • These concentration gradients provide the potential energy to drive the formation of the membrane potential. (
  • In the simplest case, illustrated here, if the membrane is selectively permeable to potassium, these positively charged ions can diffuse down the concentration gradient to the outside of the cell, leaving behind uncompensated negative charges. (
  • As we will see in the following discussion, the concentration and sign of the fixed charge in the ion-exchange membrane is crucial for the ion transport of mobile ions in the membrane. (
  • Let's apply the NPP equations to a simple problem and investigate how the ion-selective capabilities vary as we vary the concentration of the fixed ion in the membrane. (
  • For ions with a single excess charge, a concentration gradient of 1:10 across a membrane at 30C provides a 60mV potential difference- the 'resting' potential. (
  • Concentration polarization in plane membrane-solution systems. (
  • This attraction balances against the tendency of K+ to diffuse out of the cell, down its concentration gradient, and it is these combined actions that create the membrane potential. (
  • If you INCREASE the concentration of potassium in the extracellular space the concentration differences would be lower therefore the membrane potential would be more positive or partially depolarize, OR LESS NEGATIVE. (
  • Now if you REDUCE the concentration of K+ in the extracellular membrane you will DECREASE the concentration differences across the membrane and the membrane potential will be more negative (i.e. -90 to -100). (
  • With the increment of NaF concentration, the apoptotic rates and ROS generation were increased, while the [mitochondrial membrane potential] was decreased. (
  • Mitochondrial membrane potential correlates with MC degranulation through FcγR receptors and is inhibited by fullerene derivatives.In Fig 2A, change in mitochondrial membrane potential as a function of the concentration of IC stimulus was assessed. (
  • As seen in Fig 2B, change in mitochondrial membrane potential as a function of time with fixed concentration of IC stimulus was assessed. (
  • FluoVolt Membrane Potential Dye can be used for imaging electrical activity from intact heart tissues, mapping membrane potentials along neurons and muscle fibers, or measuring potential changes in response to pharmacological stimuli. (
  • Abstract: 'In this study [investigators] used the whole-cell, current clamp variant of the patch clamp technique to demonstrate that EPEC infection of HeLa and Caco-2 human epithelial cells reduces cell resting membrane potential. (
  • Di-8-ANNEPPS is more hydrophobic and better retained in the outer leaflet of the plasma membrane than Di-4-ANNEPS, and therefore is more suitable for long-term membrane potential studies. (
  • Long Term Membrane Potential (Vmem) Modulation and Cellular Senescence. (
  • The authors review recent data from patch-clamp recordings that provide new estimates of the passive membrane properties of hippocampal neurons, and show, with examples, how these properties affect the shaping and attenuation of synaptic potentials as they propagate in the dendrites, as well as how they affect the measurement of current from synapses located in the dendrites. (
  • Giant synaptic potentials in immature rat CA3 hippocampal neurones. (
  • Almost all plasma membranes have an electrical potential across them, with the inside usually negative with respect to the outside. (
  • The plasma membranes of resting axons are slightly polarized due to the unequal distribution of Na+, K+, Cl- and protein- ions in ECF and ICF. (
  • The functional significance of voltage lies only in potential differences between two points in a circuit. (
  • Differences in the concentrations of ions on opposite sides of a cellular membrane lead to a voltage called the membrane potential . (
  • The voltage differences across a membrane. (
  • Morphological differences such as extent of membrane blebbing were observed as well, verifying that cells with a high MMP are more likely to survive the cryopreservation process. (
  • Electrical potential due to the differences in the concentrations of ions on either side of a semipermeable membrane. (
  • This lesson will describe how the differences in concentrations of ions across a plasma membrane set the stage for a nerve impulse. (
  • These extracellular potentials are not filtered by the membrane. (
  • Close comparison of the measured electrical and mechanical tuning curves and time waveforms and their phase relationships revealed that those extracellular potentials indeed could drive outer hair cell motors. (
  • Consequently, prestin could be driven by the membrane potential changes that may arise as a result of the sound-evoked extracellular potentials mentioned above. (
  • The cytosol , or interior, of a cell possesses a uniform electric potential or voltage compared to the extracellular solution. (
  • When a neuron is at rest, meaning it is not firing a nerve impulse, the inside of its cell membrane has a negative charge when compared to the cell's outside. (
  • The potential is constant at rest, but changes in nerve cells when impulses are transmitted from one neuron to another. (
  • However, if the voltage is below the threshold, the neuron does not fire, but the membrane potential still fluctuates due to postsynaptic potentials and intrinsic electrical properties of neurons. (
  • an "all-or-nothing" response refers to the ability of a neuron to fire an action potential only after reaching the exact threshold. (
  • The pattern of activation of these synaptic inputs determines if the neuron will fire an action potential at any given point in time and how it will respond to similar inputs in the future. (
  • When a postsynaptic neuron is at rest (not "firing"), its membrane is polar-ized, meaning the interior is slightly more negative than the exterior. (
  • We recorded extracellularly from an identified motion-sensitive neuron while simultaneously measuring and controlling the membrane potential of individual elements of its presynaptic input ensemble. (
  • Fluorescent probes for monitoring mitochondrial membrane potential are frequently used for assessing mitochondrial function, particularly in the context of cell fate determination in biological and biomedical research. (
  • Mitochondrial membrane potential is one of the key parameters of mitochondrial function and serves as an indicator of cell health. (
  • For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. (
  • Prevailing theory states that outer hair cells use the potential-sensitive motor protein prestin to convert receptor potentials into fast alterations of cellular length or stiffness that boost hearing sensitivity almost 1000-fold. (
  • ConorEd/ElectrodeStimulation: Simple Relay Code to control the interface described in 'Electrically induced bacterial membrane-potential dynamics correspond to cellular proliferation capacity. (
  • In addition, the premature aging disease Hutchinson Gilford Progeria syndrome was used as a model to better understand the connection between membrane voltage characteristics and cellular senescence. (
  • MC inhibition by fullerene derivatives was mediated through the reduction of mitochondrial membrane potential and FcγR-mediated increases in cellular reactive oxygen species and NF-κB activation. (
  • More recently, it has been used in regenerative medicine because the amniotic-derived stem cells as well as AF-derived cells exhibit cellular plasticity, angiogenic, cytoprotective, immunosuppressive properties, antitumoural potential and the ability to generate induced pluripotent stem cells. (
  • Ion pumps and ion channels are electrically equivalent to a set of batteries and resistors inserted in the membrane, and therefore create a voltage between the two sides of the membrane. (
  • In electrically active tissue, the potential difference between any two points can be measured by inserting an electrode at each point, for example one inside and one outside the cell, and connecting both electrodes to the leads of what is in essence a specialized voltmeter. (
  • How can the there be a non-zero voltage across a membrane if the solutions on either side are electrically neutral? (
  • Between the inside and outside of the cell (which is typically uniform electrically like the cytosol ) the voltage rises very steeply just at the boundary created by the membrane . (
  • We conclude that the spine neck plays an electrical role in the transmission of membrane potentials, isolating synapses electrically. (
  • To test this theory, both electric potentials inside the organ of Corti and basilar membrane vibration were measured in response to acoustic stimulation. (
  • However, to achieve the sharp frequency tuning that characterizes the basilar membrane, additional mechanical processing must occur inside the organ of Corti. (
  • Slower opening voltage gated K channels now start opening while the Na channels start closing, and the cell starts going back toward the K Nernst potential. (
  • Voltage-gated channels might influence the measurement of 'passive' membrane properties and, reciprocally, passive membrane properties might affect the activation of voltage-gated channels in dendrites. (
  • It is the membrane potential or membrane electric field that controls the membrane flow of charged solutes and the activity of voltage-gated ion channels. (
  • This create an electric field across the membrane, which exerts a force on ions and controls voltage-gated ion channels . (
  • One way to ensure that resting membrane potential is uniform everywhere is to insert a current source into each compartment, then initialize all voltage-gated channels to some initial membrane potential v_init, and finally adjust the current delivered by each current source so that it cancels out the local ionic membrane current in each compartment. (
  • Note also that this diagram is only an approximation of the ionic contributions to the membrane potential. (
  • At the NE, no net ionic flux occurs and the membrane potential is stable. (
  • The membranes show rejection of NaCl and MgSO 4 at higher ionic strengths than have previously been reported in CNT membranes, and specific size selectivity for analytes with diameters below 1.24 nm. (
  • Only type II hair cells are present in this preparation, and they are in the physiological milieu, with the apical membrane in contact with the endolymph and the basolateral membrane surrounded by a perilymph-like solution. (
  • During sound stimulation, receptor potentials are generated within the sensory hair cells of the cochlea. (
  • However, receptor potentials are attenuated by the filter formed by the capacitance and resistance of the membrane of the cell. (
  • Their bandwidth much exceeds that of the hair cell receptor potentials. (
  • Cramer WA and Knaff DB (1990) Energy Transduction in Biological Membranes. (
  • More than a century ago, the major importance of electrical properties of biological membranes was recognized and many evidences were experimentally pointed out. (
  • As a result, Na+ ions are concentrated outside the postsynaptic membrane and K+ ions are concentrated inside the membrane. (
  • Oxonol dyes as monitors of membrane potential: the effect of viruses and toxins on the plasma membrane potential of animal cells in monolayer culture and in suspension. (
  • Membrane potential can be determined in individual cells from the Nernstian distribution of cationic dyes. (
  • In total, this review will help illustrate both the strengths and potential pitfalls of common mitochondrial membrane potential dyes, and highlight best-usage approaches for their efficacious application in life sciences research. (
  • Biotium offers a wide selection of fast- and slow-responding fluorescent membrane potential dyes, and synaptic vesicle dyes for monitoring nerve terminal activity. (
  • In cell membranes, spectra of styryl dyes are typically blue-shifted by as much as 20 nm for absorption/excitation and 80 nm for emission. (
  • In this context, we provide an overview of some of the important technical considerations, controls, and parallel complementary assays that can be employed to help ensure appropriate interpretation of results, thus providing a practical usage guide for monitoring mitochondrial membrane potentials with cationic probes. (
  • Na+/K+ pumps (or Na+/K+-ATPases) move Na+ and K+ ions to opposite sides of the membrane. (
  • Most cells maintain a membrane potential of around 80mV relative to the surrounding fluid. (
  • The exponential map is approximated locally and strain measures based on the stretch and the curvature of the membrane arise. (
  • Plásek J and Sigler K (1996) Slow fluorescent indicators of membrane potential: a survey of different approaches to probe response analysis. (
  • Measurement of mitochondrial membrane potential using fluorescent rhodamine derivatives. (
  • The green fluorescent membrane dye DiO is a "stationary" FRET donor while DPA acts as a mobile FRET acceptor, resulting in a membrane potential-dependent quenching of fluorescence by FRET. (
  • The polarity is referred to as the resting membrane potential (or RMP) and is due primarily to the unequal distribution of Na+, K+, and protein ions along the surfaces of the membrane. (
  • The unequal transfer of ions also contributes slightly to the polarity of the resting membrane. (
  • The membrane localization of the fluorescence quencher dipicrylamine (DPA) is a function of the polarity and magnitude of membrane potential. (
  • Subthreshold membrane potential oscillations are membrane oscillations that do not directly trigger an action potential since they do not reach the necessary threshold for firing. (
  • For example, figure 1 depicts the localized nature and the graded potential nature of these subthreshold membrane potential oscillations, also giving a visual representation of their placement on an action potential graph, comparing subthreshold oscillations versus a fire above the threshold. (
  • Membrane potential oscillations can be induced in molluscan neurones under a variety of artificial conditions. (
  • Foetal membranes are essential tissues for embryonic development, playing important roles related to protection, breathing, nutrition and excretion. (
  • 50 ms) reliable sensory response that was encoded through cell-specific reversal potentials. (
  • Potential generation between two electrolytic solutions separated with an ion-permeable membrane is one of fundamental phenomena in biology field known as membrane potential. (
  • Effects of unstirred layers on membrane phenomena. (
  • outward diffusion of K+ ions makes the interior of the membrane more negative and the exterior more positive, which significantly alters the RMP. (
  • Pick U and McCarty RE (1980) Measurement of membrane ΔpH. (
  • This webinar will focus on surface zeta potential analysis and exemplary measurement results derived from different membrane types related to membrane fouling, surface modification and membrane cleaning. (
  • electrical potential difference maintained across a cell membrane, with the inside negative to the outside:-110 mV to-130 mV in non-excitable cells, and -170 to -190 mV (the resting potential ) in quiescent excitable cells (nerve and muscle). (
  • Effect of nerve impulses on the membrane potential of glial cells in the central nervous system of amphibia. (
  • Increases and decreases in membrane potential play a central role in many physiological processes, including nerve-impulse propagation, muscle contraction, and cell signaling. (
  • A localized change in potential occurs at the synapse of nerve cell , for example, with the opening of ion channels by neurotransmitter . (
  • Likewise during an action potential , the magnitude of the membrane potential will vary in time and space along a nerve fiber . (
  • Healthy cells do not naturally hyperpolarize or depolarize except for brief intervals, for example during a nerve impulse or action potential . (
  • Comparative action of methylmercury and divalent inorganic mercury on nerve terminal and intraterminal mitochondrial membrane potentials. (
  • Enteropathogenic Escherichia coli markedly decreases the resting membrane potential of Caco-2 and HeLa human epithelial cells. (
  • Instead, special passages known as ion channels permit potassium ions to move out through the cell membrane, reducing the positive charge inside the cell. (
  • FluoVolt Membrane Potential Dye is a fast-response probe with a superior potential-dependent fluorescence response. (
  • I would like to know if anyone has experience with fluorecent probes for measuring membrane potential. (
  • B , Receptor current entering through transducer channels will be filtered by the parallel resistance and capacitance of the cell membrane of the outer hair cell. (