Microelectrodes: 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)Ion-Selective Electrodes: Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions.Membrane Potentials: 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).Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Electrophysiology: 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.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Potassium: 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.Fluorocarbon PolymersExtracellular Space: 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.Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Microchip Analytical Procedures: The preparation and analysis of samples on miniaturized devices.Electrochemical Techniques: The utilization of an electrical current to measure, analyze, or alter chemicals or chemical reactions in solution, cells, or tissues.Hydrogen-Ion Concentration: 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)Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Bicarbonates: Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the pH of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Strophanthidin: 3 beta,5,14-Trihydroxy-19-oxo-5 beta-card-20(22)-enolide. The aglycone cardioactive agent isolated from Strophanthus Kombe, S. gratus and other species; it is a very toxic material formerly used as digitalis. Synonyms: Apocymarin; Corchorin; Cynotoxin; Corchorgenin.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Helix (Snails): A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.Necturus: A genus of the Proteidae family with five recognized species, which inhabit the Atlantic and Gulf drainages.Micromanipulation: The performance of dissections, injections, surgery, etc., by the use of micromanipulators (attachments to a microscope) that manipulate tiny instruments.Necturus maculosus: A neotenic aquatic species of mudpuppy (Necturus) occurring from Manitoba to Louisiana and Texas.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Conductometry: Determination of the quantity of a material present in a mixture by measurement of its effect on the electrical conductivity of the mixture. (Webster, 3d ed)Glass: Hard, amorphous, brittle, inorganic, usually transparent, polymerous silicate of basic oxides, usually potassium or sodium. It is used in the form of hard sheets, vessels, tubing, fibers, ceramics, beads, etc.Equipment Failure Analysis: The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.Dielectric Spectroscopy: A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.Neurons: 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.Guinea Pigs: 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.Intracellular Fluid: The fluid inside CELLS.Leeches: Annelids of the class Hirudinea. Some species, the bloodsuckers, may become temporarily parasitic upon animals, including man. Medicinal leeches (HIRUDO MEDICINALIS) have been used therapeutically for drawing blood since ancient times.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Diamond: Diamond. A crystalline form of carbon that occurs as hard, colorless or tinted isomeric crystals. It is used as a precious stone, for cutting glass, and as bearings for delicate mechanisms. (From Grant & Hackh's Chemical Dictionary, 5th ed)Potentiometry: Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Biosensing Techniques: Any of a variety of procedures which use biomolecular probes to measure the presence or concentration of biological molecules, biological structures, microorganisms, etc., by translating a biochemical interaction at the probe surface into a quantifiable physical signal.Miniaturization: The design or construction of objects greatly reduced in scale.Ion Transport: 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.Partial Pressure: The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Dimethadione: An anticonvulsant that is the active metabolite of TRIMETHADIONE.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Electric Impedance: The resistance to the flow of either alternating or direct electrical current.Equipment Design: Methods of creating machines and devices.Calcium: 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.Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Polarography: An electrochemical technique for measuring the current that flows in solution as a function of an applied voltage. The observed polarographic wave, resulting from the electrochemical response, depends on the way voltage is applied (linear sweep or differential pulse) and the type of electrode used. Usually a mercury drop electrode is used.4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid: A non-penetrating amino reagent (commonly called SITS) which acts as an inhibitor of anion transport in erythrocytes and other cells.4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid: An inhibitor of anion conductance including band 3-mediated anion transport.Ion Exchange: 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.Electroplating: Coating with a metal or alloy by electrolysis.LacquerQuaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.Ethoxzolamide: A carbonic anhydrase inhibitor used as diuretic and in glaucoma. It may cause hypokalemia.Amiloride: A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)Cortical Spreading Depression: The decrease in neuronal activity (related to a decrease in metabolic demand) extending from the site of cortical stimulation. It is believed to be responsible for the decrease in cerebral blood flow that accompanies the aura of MIGRAINE WITH AURA. (Campbell's Psychiatric Dictionary, 8th ed.)Papillary Muscles: Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.Benzolamide: Selective renal carbonic anhydrase inhibitor. It may also be of use in certain cases of respiratory failure.Evoked Potentials: 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.Brain Waves: Wave-like oscillations of electric potential between parts of the brain recorded by EEG.Ouabain: 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.Patch-Clamp Techniques: 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.Barium: 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.Carbonic Anhydrase Inhibitors: A class of compounds that reduces the secretion of H+ ions by the proximal kidney tubule through inhibition of CARBONIC ANHYDRASES.Sodium-Bicarbonate Symporters: Proteins that cotransport sodium ions and bicarbonate ions across cellular membranes.Dark Adaptation: Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.Microtechnology: Manufacturing technology for making microscopic devices in the micrometer range (typically 1-100 micrometers), such as integrated circuits or MEMS. The process usually involves replication and parallel fabrication of hundreds or millions of identical structures using various thin film deposition techniques and carried out in environmentally-controlled clean rooms.Iontophoresis: Therapeutic introduction of ions of soluble salts into tissues by means of electric current. In medical literature it is commonly used to indicate the process of increasing the penetration of drugs into surface tissues by the application of electric current. It has nothing to do with ION EXCHANGE; AIR IONIZATION nor PHONOPHORESIS, none of which requires current.Rana pipiens: A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.Buffers: A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.Tetrodotoxin: 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.Rabbits: 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.Extracellular Fluid: The fluid of the body that is outside of CELLS. It is the external environment for the cells.Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Ions: 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.Endolymph: The lymph fluid found in the membranous labyrinth of the ear. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Rats, Sprague-Dawley: 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.Acid-Base Equilibrium: The balance between acids and bases in the BODY FLUIDS. The pH (HYDROGEN-ION CONCENTRATION) of the arterial BLOOD provides an index for the total body acid-base balance.Ion Channels: 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.Alkalies: Usually a hydroxide of lithium, sodium, potassium, rubidium or cesium, but also the carbonates of these metals, ammonia, and the amines. (Grant & Hackh's Chemical Dictionary, 5th ed)Rana esculenta: An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".Time Factors: Elements of limited time intervals, contributing to particular results or situations.Silicon: A trace element that constitutes about 27.6% of the earth's crust in the form of SILICON DIOXIDE. It does not occur free in nature. Silicon has the atomic symbol Si, atomic number 14, and atomic weight [28.084; 28.086].Retina: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.Nanocomposites: Nanometer-scale composite structures composed of organic molecules intimately incorporated with inorganic molecules. (Glossary of Biotechnology and Nanobiotechology Terms, 4th ed)Octanols: Isomeric forms and derivatives of octanol (C8H17OH).Muscles: Contractile tissue that produces movement in animals.Perilymph: The fluid separating the membranous labyrinth from the osseous labyrinth of the ear. It is entirely separate from the ENDOLYMPH which is contained in the membranous labyrinth. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1396, 642)Synaptic Transmission: 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.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Gold: A yellow metallic element with the atomic symbol Au, atomic number 79, and atomic weight 197. It is used in jewelry, goldplating of other metals, as currency, and in dental restoration. Many of its clinical applications, such as ANTIRHEUMATIC AGENTS, are in the form of its salts.Ganglia: Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.Dopamine: One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.Rana temporaria: A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Osmolar Concentration: 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.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Oxygen Consumption: 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)Photoreceptor Cells: Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.Sinoatrial Node: The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).Electroencephalography: Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.Dimethylpolysiloxanes: Silicone polymers which consist of silicon atoms substituted with methyl groups and linked by oxygen atoms. They comprise a series of biocompatible materials used as liquids, gels or solids; as film for artificial membranes, gels for implants, and liquids for drug vehicles; and as antifoaming agents.Ammonium Chloride: An acidifying agent that has expectorant and diuretic effects. Also used in etching and batteries and as a flux in electroplating.Motion: Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.Dogs: 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)Calibration: Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Catecholamines: A general class of ortho-dihydroxyphenylalkylamines derived from tyrosine.Microchemistry: The development and use of techniques and equipment to study or perform chemical reactions, with small quantities of materials, frequently less than a milligram or a milliliter.Platinum: Platinum. A heavy, soft, whitish metal, resembling tin, atomic number 78, atomic weight 195.09, symbol Pt. (From Dorland, 28th ed) It is used in manufacturing equipment for laboratory and industrial use. It occurs as a black powder (platinum black) and as a spongy substance (spongy platinum) and may have been known in Pliny's time as "alutiae".Potassium Channels: 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.Peroneal Nerve: The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Acetylcholine: 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.Bumetanide: A sulfamyl diuretic.Muscle Contraction: 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.Prostheses and Implants: Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.Sodium Chloride: A ubiquitous sodium salt that is commonly used to season food.Diffusion: 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.Quinidine: An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.Potassium Channel Blockers: 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.Submucous Plexus: One of two ganglionated neural networks which together form the enteric nervous system. The submucous (Meissner's) plexus is in the connective tissue of the submucosa. Its neurons innervate the epithelium, blood vessels, endocrine cells, other submucosal ganglia, and myenteric ganglia, and play an important role in regulating ion and water transport. (From FASEB J 1989;3:127-38)Automatic Data Processing: Data processing largely performed by automatic means.Osmosis: Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.Tetraethylammonium CompoundsSkin Physiological Phenomena: The functions of the skin in the human and animal body. It includes the pigmentation of the skin.Potassium Chloride: 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.Rats, Inbred Strains: 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.Artifacts: Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.Neuromuscular Junction: The synapse between a neuron and a muscle.Heart: The hollow, muscular organ that maintains the circulation of the blood.Chromaffin Cells: Cells that store epinephrine secretory vesicles. During times of stress, the nervous system signals the vesicles to secrete their hormonal content. Their name derives from their ability to stain a brownish color with chromic salts. Characteristically, they are located in the adrenal medulla and paraganglia (PARAGANGLIA, CHROMAFFIN) of the sympathetic nervous system.Ventricular Function: The hemodynamic and electrophysiological action of the HEART VENTRICLES.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.Muscle, Smooth: 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)Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Models, Biological: 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.Acidosis: A pathologic condition of acid accumulation or depletion of base in the body. The two main types are RESPIRATORY ACIDOSIS and metabolic acidosis, due to metabolic acid build up.Anura: 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.Tetraethylammonium: A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)Motor Neurons: Neurons which activate MUSCLE CELLS.Somatosensory Cortex: Area of the parietal lobe concerned with receiving sensations such as movement, pain, pressure, position, temperature, touch, and vibration. It lies posterior to the central sulcus.Caffeine: A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.Cerebral Cortex: The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Astacoidea: A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.Hydrogen: The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.Serotonin: A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.Glyburide: An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Acids: Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. (Grant & Hackh's Chemical Dictionary, 5th ed)Mathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Fluorescent Dyes: 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.Synapses: 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.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Sodium-Potassium-Exchanging ATPase: 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.Xenopus laevis: 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.Body Fluids: Liquid components of living organisms.Isoproterenol: Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.Electrophysiological Phenomena: The electrical properties, characteristics of living organisms, and the processes of organisms or their parts that are involved in generating and responding to electrical charges.Electroretinography: Recording of electric potentials in the retina after stimulation by light.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Chloride-Bicarbonate Antiporters: Electroneutral chloride bicarbonate exchangers that allow the exchange of BICARBONATE IONS exchange for CHLORIDE IONS across the cellular membrane. The action of specific antiporters in this class serve important functions such as allowing the efficient exchange of bicarbonate across red blood cell membranes as they passage through capillaries and the reabsorption of bicarbonate ions by the kidney.

Molecular dynamics of the sodium channel pore vary with gating: interactions between P-segment motions and inactivation. (1/2595)

Disulfide trapping studies have revealed that the pore-lining (P) segments of voltage-dependent sodium channels undergo sizable motions on a subsecond time scale. Such motions of the pore may be necessary for selective ion translocation. Although traditionally viewed as separable properties, gating and permeation are now known to interact extensively in various classes of channels. We have investigated the interaction of pore motions and voltage-dependent gating in micro1 sodium channels engineered to contain two cysteines within the P segments. Rates of catalyzed internal disulfide formation (kSS) were measured in K1237C+W1531C mutant channels expressed in oocytes. During repetitive voltage-clamp depolarizations, increasing the pulse duration had biphasic effects on the kSS, which first increased to a maximum at 200 msec and then decreased with longer depolarizations. This result suggested that occupancy of an intermediate inactivation state (IM) facilitates pore motions. Consistent with the known antagonism between alkali metals and a component of slow inactivation, kSS varied inversely with external [Na+]o. We examined the converse relationship, namely the effect of pore flexibility on gating, by measuring recovery from inactivation in Y401C+E758C (YC/EC) channels. Under oxidative conditions, recovery from inactivation was slower than in a reduced environment in which the spontaneous YC/EC cross-link is disrupted. The most prominent effects were slowing of a component with intermediate recovery kinetics, with diminution of its relative amplitude. We conclude that occupancy of an intermediate inactivation state facilitates motions of the P segments; conversely, flexibility of the P segments alters an intermediate component of inactivation.  (+info)

Cerebellar Purkinje cell simple spike discharge encodes movement velocity in primates during visuomotor arm tracking. (2/2595)

Pathophysiological, lesion, and electrophysiological studies suggest that the cerebellar cortex is important for controlling the direction and speed of movement. The relationship of cerebellar Purkinje cell discharge to the control of arm movement parameters, however, remains unclear. The goal of this study was to examine how movement direction and speed and their interaction-velocity-modulate Purkinje cell simple spike discharge in an arm movement task in which direction and speed were independently controlled. The simple spike discharge of 154 Purkinje cells was recorded in two monkeys during the performance of two visuomotor tasks that required the animals to track targets that moved in one of eight directions and at one of four speeds. Single-parameter regression analyses revealed that a large proportion of cells had discharge modulation related to movement direction and speed. Most cells with significant directional tuning, however, were modulated at one speed, and most cells with speed-related discharge were modulated along one direction; this suggested that the patterns of simple spike discharge were not adequately described by single-parameter models. Therefore, a regression surface was fitted to the data, which showed that the discharge could be tuned to specific direction-speed combinations (preferred velocities). The overall variability in simple spike discharge was well described by the surface model, and the velocities corresponding to maximal and minimal discharge rates were distributed uniformly throughout the workspace. Simple spike discharge therefore appears to integrate information about both the direction and speed of arm movements, thereby encoding movement velocity.  (+info)

Neural encoding in orbitofrontal cortex and basolateral amygdala during olfactory discrimination learning. (3/2595)

Orbitofrontal cortex (OFC) is part of a network of structures involved in adaptive behavior and decision making. Interconnections between OFC and basolateral amygdala (ABL) may be critical for encoding the motivational significance of stimuli used to guide behavior. Indeed, much research indicates that neurons in OFC and ABL fire selectively to cues based on their associative significance. In the current study recordings were made in each region within a behavioral paradigm that allowed comparison of the development of associative encoding over the course of learning. In each recording session, rats were presented with novel odors that were informative about the outcome of making a response and had to learn to withhold a response after sampling an odor that signaled a negative outcome. In some cases, reversal training was performed in the same session as the initial learning. Ninety-six of the 328 neurons recorded in OFC and 60 of the 229 neurons recorded in ABL exhibited selective activity during evaluation of the odor cues after learning had occurred. A substantial proportion of those neurons in ABL developed selective activity very early in training, and many reversed selectivity rapidly after reversal. In contrast, those neurons in OFC rarely exhibited selective activity during odor evaluation before the rats reached the criterion for learning, and far fewer reversed selectivity after reversal. The findings support a model in which ABL encodes the motivational significance of cues and OFC uses this information in the selection and execution of an appropriate behavioral strategy.  (+info)

Correlated firing in rabbit retinal ganglion cells. (4/2595)

A ganglion cell's receptive field is defined as that region on the retinal surface in which a light stimulus will produce a response. While neighboring ganglion cells may respond to the same stimulus in a region where their receptive fields overlap, it generally has been assumed that each cell makes an independent decision about whether to fire. Recent recordings from cat and salamander retina using multiple electrodes have challenged this view of independent firing by showing that neighboring ganglion cells have an increased tendency to fire together within +/-5 ms. However, there is still uncertainty about which types of ganglion cells fire together, the mechanisms that produce coordinated spikes, and the overall function of coordinated firing. To address these issues, the responses of up to 80 rabbit retinal ganglion cells were recorded simultaneously using a multielectrode array. Of the 11 classes of rabbit ganglion cells previously identified, coordinated firing was observed in five. Plots of the spike train cross-correlation function suggested that coordinated firing occurred through two mechanisms. In the first mechanism, a spike in an interneuron diverged to produce simultaneous spikes in two ganglion cells. This mechanism predominated in four of the five classes including the ON brisk transient cells. In the second mechanism, ganglion cells appeared to activate each other reciprocally. This was the predominant pattern of correlated firing in OFF brisk transient cells. By comparing the receptive field profiles of ON and OFF brisk transient cells, a peripheral extension of the OFF brisk transient cell receptive field was identified that might be produced by lateral spike spread. Thus an individual OFF brisk transient cell can respond both to a light stimulus directed at the center of its receptive field and to stimuli that activate neighboring OFF brisk transient cells through their receptive field centers.  (+info)

Thapsigargin inhibits a potassium conductance and stimulates calcium influx in the intact rat lens. (5/2595)

1. An increase in lens cell calcium has long been associated with cortical cataract. Recently, it has been shown that thapsigargin induces a rise in lens cell calcium by release from endoplasmic reticulum stores. The effects of this rise on the optical and membrane characteristics of the lens were studied in the isolated rat lens. 2. The electrical characteristics of the isolated, perifused rat lens were measured using a two-internal microelectrode technique that permits measurement of plasma membrane conductance (Gm), membrane potential (Vm) and junctional conductance in the intact lens. 3. Thapsigargin (1 microM) induced a rapid overall depolarization of Vm that was accompanied by first a decrease and then an increase in Gm. 4. Replacing external Na+ with tetraethylammonium (TEA) abolished the decrease in Gm. However, a transient increase phase was still observed. 5. The changes in conductance were further characterized by measuring 22Na+ and 45Ca2+ influxes into the isolated lens. Thapsigargin (1 microM) induced a transient increase in 45Ca2+, but did not affect Na+ influx. 6. The Ca2+ channel blocker La3+ (10 microM) totally inhibited the thapsigargin-induced Ca2+ influx. It also blocked the increase in Gm observed in control and in Na+-free-TEA medium. In the absence of external calcium, thapsigargin induced a small depolarization in Vm. 7. These data indicate that thapsigargin induces both a decrease in K+ conductance and an increase in Ca2+ conductance. These probably result from release of stored Ca2+ and subsequent activation of store-operated Ca2+ channels (capacitative Ca2+ entry). 8. Thapsigargin application over the time course of these experiments (24 h) had no effect on junctional conductance or on the transparency of the lens.  (+info)

Nitric oxide release in penile corpora cavernosa in a rat model of erection. (6/2595)

1. Nitric oxide (NO) levels were measured in the corpus cavernosum of urethane-anaesthetized rats by using differential normal pulse voltammetry with carbon fibre microelectrodes coated with a polymeric porphyrin and a cation exchanger (Nafion). A NO oxidation peak could be recorded at 650 mV vs. a Ag-AgCl reference electrode every 100 s. 2. This NO signal was greatly decreased by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), given by local and systemic routes, and enhanced by the NO precursor L-arginine. Treatment with L-arginine reversed the effect of L-NAME on the NO peak. 3. Both the NO signal and the intracavernosal pressure (ICP) were increased by electrical stimulation of cavernosal nerves (ESCN). However, the rise in the NO levels long outlived the rapid return to baseline of the ICP values at the end of nerve stimulation. 4. The ICP and the NO responses to ESCN were suppressed by local and systemic injections of L-NAME. Subsequent treatment with L-arginine of L-NAME-treated animals restored the NO signal to basal levels and the NO response to ESCN. The ICP response to ESCN was restored only in part by L-arginine. 5. The observed temporal dissociation between the NO and ICP responses could be accounted for by several factors, including the buffering of NO by the blood filling the cavernosal spaces during erection. 6. These findings indicate that an increased production of NO in the corpora cavernosa is necessary but not sufficient for maintaining penile erection and suggest a complex modulation of the NO-cGMP-cavernosal smooth muscle relaxation cascade.  (+info)

In vitro simultaneous measurements of relaxation and nitric oxide concentration in rat superior mesenteric artery. (7/2595)

1. The relationship between nitric oxide (NO) concentration measured with an NO-specific microelectrode and endothelium-dependent relaxation was investigated in isolated rat superior mesenteric artery contracted with 1 microM noradrenaline. 2. Acetylcholine (10 microM) induced endothelium-dependent simultaneous increases in luminal NO concentration of 21 +/- 6 nM, and relaxations with pD2 values and maximum of 6.95 +/- 0.32 and 97.5 +/- 0.7 % (n = 7), respectively. An inhibitor of NO synthase, N G-nitro-L-arginine (L-NOARG, 100 microM) inhibited the relaxations and increases in NO concentration induced by acetylcholine. 3. Oxyhaemoglobin (10 microM) reversed the relaxations and increases in NO concentrations induced by acetylcholine, S-nitroso-N-acetylpenicillamine (SNAP) and S-morpholino-sydnonimine (SIN-1), but not the relaxations induced with forskolin. Oxyhaemoglobin also decreased the NO concentration below baseline level. 4. In the presence of L-NOARG (100 microM), a small relaxation to acetylcholine (10 microM) of noradrenaline-contracted segments was still seen; oxyhaemogobin inhibited this relaxation and decreased the NO concentration by 14 +/- 4 nM (n = 4). 5. The NO concentration-relaxation relationship for acetylcholine resembled that for SNAP and SIN-1 more than for authentic NO. Thus while 7-17 nM NO induced half-maximal relaxations in response to SNAP or SIN-1, 378 +/- 129 nM NO (n = 4) was needed for half-maximal relaxation to authentic NO. 6. The present study provides direct evidence that the relaxation of the rat superior mesenteric artery with the endothelium-dependent vasodilator acetylcholine is correlated to the endogeneous release of NO. The study also suggests that NO mediates the L-NOARG-resistant relaxations in this artery, and that there is a basal NO release.  (+info)

Firing properties of single vasoconstrictor neurones in human subjects with high levels of muscle sympathetic activity. (8/2595)

1. Single-unit recordings were made from 19 postganglionic muscle vasoconstrictor axons via tungsten microelectrodes in the peroneal nerve in seven healthy subjects with many multi-unit sympathetic discharges at rest ('high group', 75 +/- 5 multi-unit bursts per 100 heart beats, mean +/- s.e.m.). The results were compared with previous data from 14 units in subjects with 21 +/- 2 multi-unit bursts per 100 heart beats ('low group'). 2. In the 'high group' the units fired spontaneously in 35 +/- 4 % of all cardiac intervals. One unit only ever fired once per cardiac interval, 14 units (74 %) generated maximally two to three spikes, and four units (21 %) up to four to five spikes. Of those cardiac intervals in which a unit fired, a single spike occurred in 78 %, two spikes in 18 %, three spikes in 4 % and four spikes in less than 1 % of cardiac intervals. Measured as the inverse of all interspike intervals, the mean rate was 0.33 +/- 0.04 Hz and the mean intraburst frequency 22.2 +/- 1.6 Hz. Most results were similar to those in the 'low group', but in the 'low group' heart rate was higher (64.5 vs. 50.4 beats min-1) and mean firing frequency was higher (0.49 +/- 0.06 Hz). 3. During increases of multi-unit burst activity evoked by sustained inspiratory-capacity apnoea the firing probability of nine units in the 'high group' increased from 33 +/- 6 to 56 +/- 3 % of the cardiac intervals. Simultaneously, the incidence of single spikes decreased and the incidence of multiple spikes per cardiac interval increased, resulting in an increase of mean firing frequency from 0. 23 +/- 0.04 Hz at rest to 1.04 +/- 0.14 Hz during the apnoea. 4. We conclude that single muscle vasoconstrictor neurones usually fire only a solitary spike during sympathetic bursts both in subjects with a high and in subjects with a low number of bursts at rest. Presumably, differences in the numbers of bursts are due mainly to differences in firing probability and recruitment of sympathetic fibres. During acute increases of multi-unit activity, both increases in discharge frequency and recruitment of additional neurones contribute to the increased intensity of an individual sympathetic burst.  (+info)

  • To overcome the limitations of previous in vivo extracellular Glu studies, we developed Glu selective microelectrode arrays with better spatial and temporal resolutions than commonly used techniques like microdialysis. (uky.edu)
  • We used these microelectrode arrays to characterize basal and potassium-evoked Glu neurotransmission in the normal rat brain. (uky.edu)
  • The multi-microelectrode probe (microprobe) is a device that has been developed mainly for CNS applications. (bio.net)
  • It has been suggested that multi-microelectrode probes (microprobes) implanted into the peripheral nervous system can be used to detect signals originating from the body's own sensors. (surrey.ac.uk)
  • In some embodiments, an implantable microelectrode is provided with a shank comprised of a laterally extending platform whose thickness and/or configuration contributes to reduced tissue encapsulation, with at least one electrode site disposed at least partially on or in the laterally extending platform. (google.com)
  • Novel methods of designing, making, and using an implantable microelectrode or biosensor resulting in reduced tissue encapsulation are also disclosed. (google.com)
  • 2. The implantable microelectrode of claim 1 , wherein the laterally extending platform further comprises at least one longitudinal rib and at least one radially projecting rib projecting from the portion and wherein the configuration of the longitudinal rib, the radially extending rib, and the backbone portion form at least one open space in the laterally extending platform. (google.com)
  • 3. The implantable microelectrode of claim 2 , wherein at least one electrode site is disposed at least partially on or in the longitudinal rib. (google.com)
  • 4. The implantable microelectrode of claim 1 or 2 , wherein the laterally extending platform has a thickness between about 0.5 and 10 microns. (google.com)
  • 5. The implantable microelectrode of claim 1 or 2 , wherein the at least one electrode site includes a plurality of microelectrodes disposed on the laterally extending platform. (google.com)
  • 6. The implantable microelectrode of claim 5 , wherein at least one of the electrode sites is disposed on the most lateral edge of the laterally extending platform or within about 10 microns of the most lateral edge. (google.com)
  • 7. The implantable microelectrode of claim 1 or 2 , wherein the shank further comprises a tip whose shape is chiseled, conical, frusto-conical, or any combination thereof. (google.com)
  • 8. The implantable microelectrode of claim 1 or 2 , wherein the backbone portion and the laterally extending platform further comprise at least one layer of a non-conductive material and a layer of electrically conductive material comprising at least one electrical channel on top of the non-conductive material or between multiple layers of a non-conductive material. (google.com)
  • 10. The implantable microelectrode of claim 9 , wherein the at least one electrode site disposed at least partially on or in the laterally extending platform comprises surface area disposed at least partially on or in the top, bottom, and/or most lateral sides of the laterally extending platform. (google.com)
  • Implantable microelectrodes have the potential to become part of neural prostheses to restore lost nerve function after nerve damage. (surrey.ac.uk)
  • The initial adsorption of proteins to materials for implantable microelectrodes is an important factor in determining the longevity and stability of the implant. (surrey.ac.uk)
  • The aim of this study was to identify an optimum material for electrode recording sites on implantable microelectrodes. (surrey.ac.uk)
  • The adsorbed protein layers on gold (after 7 and 28 days of exposure to serum) were the smoothest and the thinnest compared to all the other substrate materials, indicating that gold is the material of choice for electrode recording sites on implantable microelectrodes. (surrey.ac.uk)
  • The effective surface area of individual microelectrodes is significantly increased using electrochemical activation, a procedure that may also be employed to restore the properties of the electrodes as required. (epfl.ch)
  • Depending on the desired application, different 3D carbon microelectrodes can be fabricated (figure 1.B). Figure 1.C shows the electrochemical characterization of a three electrodes system, comparing planar and 3D carbon working electrodes. (dtu.dk)
  • A new microelectrode design with decreased diameter was introduced in May 2004, and data from the 2 types of electrodes were compared. (nih.gov)
  • The results obtained for the poly(aniline)-(polystyrene sulfonate) coated microelectrode are compared to those for a poly(aniline)-poly(vinyl sulfonate) coated microelectrode and to the results of an earlier study of the reaction at poly(aniline)-poly(vinyl sulfonate) coated rotating disc electrodes. (soton.ac.uk)
  • Methods and Results We studied the effects of 10 and 25 μmol/L pinacidil, an ATP-sensitive K channel opener that provides metabolic protection to the ischemic myocardium, on the rise in [K + ] e recorded by K-sensitive electrodes, the change in action potential duration (APD) recorded by microelectrodes, and the changes in activation during ischemia in in situ pig hearts and Tyrode-perfused rabbit interventricular septa. (ahajournals.org)
  • Unlike in bulk electroporation, where hundreds of volts may be applied between electrodes, a rather small voltage is applied to a microelectrode in single-cell electroporation. (chalmers.se)
  • Here, we developed an interdigitated microelectrode (IME) biosensor coated with an anti-BDNF an anti-BDNF antibody in a polydimethylsiloxane (PDMS)-based microfluidic channel chip. (nih.gov)
  • A simple, single-masked gold interdigitated triple-microelectrodes biosensor is presented by taking the advantage of an effective self-assembled monolayer (SAM) using an amino-silanization technique for the early detection of a prostate cancer's biomarker, the prostate-specific antigen (PSA). (bath.ac.uk)
  • Single-unit recording Microelectrode array Cogan, Stuart F. (August 2008). (wikipedia.org)
  • The image on the right is a magnification of a microelectrode array tip with 50 × 150 μm 2 sites. (nih.gov)
  • Room temperature ionic liquids (RTILs) have been applied to a microelectrode array,and been demonstrated to form effective, membrane-free amperometric gas sensors. (csic.es)
  • The combination of microelectrode array and RTIL, as well as the absence of membrane and volatile solvent, results in an elegant, easy to calibrate gas sensor with potential utility in standard and non-standard conditions. (csic.es)
  • At Axion Biosystems, his team identifies, develops, and implements advanced applications for the Maestro Pro and Maestro Edge multiwell microelectrode array platforms. (labroots.com)
  • Enter the microelectrode array (MEA) and the Maestro platform from Axion BioSystems: a simple approach to measuring complex, functional neural responses at the throughput level you need. (labroots.com)
  • Processing and analysis of the signals from the microelectrode array demonstrated distinct ECG signals: namely, atrial conduction (P waves), ventricular contraction (QRS), and ventricular repolarization (QT interval). (caltech.edu)
  • To this end, we have realized and functionally characterized a Pt microelectrode array with an integrated EPON SU-8 clustering structure, allowing to confine five relatively large yet interconnected spontaneously developing neuronal networks (i.e. thousands of cells). (rero.ch)
  • The study presents a dielectrophoretic cell separation method via three-dimensional (3D) nonuniform electric fields generated by employing a periodic array of discrete but locally asymmetric triangular bottom microelectrodes and a continuous top electrode. (ntu.edu.sg)
  • The cells that experience stronger positive dielectrophoresis are streamed further in the perpendicular direction to the fluid flow, leaving the cells that experience weak positive dielectrophoresis, which continue to traverse the microelectrode array essentially along the laminar flow streamlines. (ntu.edu.sg)
  • A key component of the proposed assay utilizes human stem cell derived cardiomyocytes (hSC-CMs) and microelectrode array (MEA) technology to evaluate the proarrhythmic risk of candidate compounds . (technologynetworks.com)
  • In this experiment, the microelectrodes in the array are used as anodes in order to oxidize an iron species (typically ferrocene or ferricyanide) in the solution covering the array. (wustl.edu)
  • When a receptor (M 1 R) is added to the solution above the array and binds to ligands on the array (M 1 , M 2 , etc.) the iron species is impeded from reaching the neighboring microelectrodes. (wustl.edu)
  • Adaptation of Microelectrode Array Technology for the Study of Anesthesia-induced Neurotoxicity in the Intact Piglet Brain. (smarttots.org)
  • This protocol adapts the use of enzyme-based microelectrode array (MEA) technology as a novel way to study the mechanism(s) of anesthesia-induced neurotoxicity (AIN). (smarttots.org)
  • Structure and function of a nitrifying biofilm as determined by in situ hybridization and the use of microelectrodes. (asm.org)
  • Electrical potential and resistance were measured with microelectrodes in in situ and isolated nuclei of gland cells of Drosophila flavorepleta . (rupress.org)
  • Microelectrodes and fluorescent in situ hybridization (FISH) in biofilm research have been used to investigate the spatial distributions of various microbial activities in biofilms and have led to new experimental findings as well as modifications of the homogeneous assumptions in the biofilm kinetic models. (iwaponline.com)
  • The objective of this study is to try the combination of two methods, both FISH and microelectrode measurements, and to provide reliable and in situ information on nitrifying bacterial activity in biofilms. (iwaponline.com)
  • In this study, we examined the existence of gamma oscillations during polysomnographically defined sleep-wake states using large-scale microelectrode recordings (up to 56 channels), with single-cell and spike-time precision, in epilepsy patients. (jneurosci.org)
  • Multi-unit recordings obtained from current fixed microelectrode technologies typically show deterioration in signal quality with time and almost all of them fail over periods ranging from few weeks to few years. (pubmedcentralcanada.ca)
  • Further, the same microelectrode technology can often yield successful multi-unit recordings for widely varying durations of time before they fail. (pubmedcentralcanada.ca)
  • Recent studies and prior reports indicate changes in enzyme activity and selectivity with certain glutaraldehyde cross-linking procedures that may jeopardize the performance of microelectrode recordings and lead to falsely elevated responses in biological systems. (nih.gov)
  • In this study, we propose and evaluate a technique known as common average referencing (CAR) to generate a more ideal reference electrode for microelectrode recordings. (semanticscholar.org)
  • Trans sarcolemmal Ca movements in rabbit and rat ventricular muscle were compared using extracellular double-barreled Ca-selective microelectrodes. (elsevier.com)
  • An alternative approach, useful for rapidly transporting Malpighian tubules, is to position an extracellular K + -selective microelectrode in the unstirred layer adjacent the basolateral membrane. (biologists.org)
  • The microelectrode electrical signals allowed for a high level of both temporal and spatial resolution (~20 μm), and the signal to noise ratio of the epicardial ECG was comparable to that of surface electrode ECG (7.1 dB vs. 7.4 dB, respectively). (caltech.edu)
  • With regard to charge transfer capacity and signal-to-noise ratio, microelectrode properties can be optimized by nano modification, e.g., coating with nano-lawn structures. (arvojournals.org)
  • Three-microelectrode voltage clamp experiments in calf cardiac Purkinje fibers: is slow inward current adequately measured? (springer.com)
  • Two of the twelve movable microelectrode chips were not moved over a period of 3 weeks and were treated as control experiments. (pubmedcentralcanada.ca)
  • The results of this study demonstrate that MEMS based technologies can move microelectrodes in rodent brains in long-term experiments resulting in improvements in signal quality. (pubmedcentralcanada.ca)
  • However, current microelectrode technologies are inconsistent in their performance and unreliable in long-term experiments. (pubmedcentralcanada.ca)
  • As expected, characterization of bare microelectrodes in buffer and tracking experiments with HeLa cells over 16 hours demonstrate that the coplanar configuration provides a higher sensitivity to cell adhesion and spreading (Cell Index = 1.6 vs. 0.4) albeit at a higher frequency of maximum sensitivity (100kHz vs. 24 kHz). (dtu.dk)
  • With regard to direct and indirect cell contact, the tested nano-lawn structures showed good biocompatibility profiles, demonstrating that this nanotechnology provides a promising tool to improve microelectrodes that connect with retinal tissue. (arvojournals.org)
  • We have patterned silver microelectrodes by omnidirectional printing of concentrated nanoparticle inks in both uniform and high-aspect ratio motifs with minimum widths of approximately 2 micrometers onto semiconductor, plastic, and glass substrates. (sciencemag.org)
  • This paper describes improved sensitivity when using biosensors based on microfabricated microelectrodes to detect DNA, with the goal of progressing towards a low cost and mass manufacturable assay for antibiotic resistance in tuberculosis (TB). (strath.ac.uk)
  • The microelectrodes gave a near 20 times improvement in sensitivity compared to polycrystalline macroelectrodes. (strath.ac.uk)
  • However, the electrophysiological activity of such large-scale neuronal networks is recorded only by tens/hundreds microelectrodes. (biomedcentral.com)
  • Single-cell electroporation uses microelectrodes, capillaries, or micropipets positioned near single, adherent cells to increase transiently the membrane permeability of the cell. (chalmers.se)
  • The conductive lines connect microelectrodes found near an insertion end of the probe to respective leads at a connector end of the probe. (energy.gov)
  • The workshop provides intensive practical tuition in a number of microelectrode, patch clamp and optical techniques applied to single cells and whole tissues. (mba.ac.uk)
  • In this study, believed to be the first quantitative, large-scale microelectrode recording in human cortex, we examined gamma patterns during sleep using multiple microwires (up to 56) in patients with epilepsy who required presurgical clinical evaluation. (jneurosci.org)
  • In this study, a total of 12 movable microelectrode chips were individually implanted in adult rats. (pubmedcentralcanada.ca)
  • All microelectrode-guided DBS procedures performed at our institution between January 2000 and March 2008 were included in this study. (nih.gov)
  • A detailed kinetic study is provided for the oxidation of ascorbate at poly(aniline)-poly(styrene sulfonate) coated microelectrodes. (soton.ac.uk)
  • Schematic diagram (not to scale) showing the self-referencing ion-selective (SeRIS) microelectrode for the study of K + transport by isolated Malpighian tubules. (biologists.org)
  • Traversing through the microelectrodes, heterogeneous cells are electrically polarized to experience different strengths of positive dielectrophoretic forces, in response to the 3D nonuniform electric fields. (ntu.edu.sg)
  • In 1947 he co-developed the Gerard-Graham-Ling microelectrode , a device that allows scientists to more accurately measure the electrical potentials of living cells. (wikipedia.org)
  • Shattock, MJ & Bers, DM 1989, ' Rat vs. rabbit ventricle: Ca flux and intracellular Na assessed by ion-selective microelectrodes ', American Journal of Physiology - Cell Physiology , vol. 256, no. 4. (elsevier.com)
  • The patterned microelectrodes can withstand repeated bending and stretching to large levels of strain with minimal degradation of their electrical properties. (sciencemag.org)
  • A new microelectrode design minimizing the volume of brain parenchyma penetrated during microelectrode recording leads to decreased rates of hemorrhage, particularly if the ventricles are breached. (nih.gov)
  • This series describes the outcomes of 79 consecutive patients that underwent bilateral STN DBS at the National Hospital for Neurology and Neurosurgery between November 2002 and November 2008 using an MRI-guided surgical technique without microelectrode recording. (bmj.com)
  • This series confirms that image-guided STN DBS without microelectrode recording can lead to substantial improvements in motor disability of well-selected PD patients with accompanying improvements in quality of life and most importantly, with very low morbidity. (bmj.com)
  • The accuracy of electrode placement has been studied by the use of intraoperative imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT),3,4 as well as the continued use of microelectrode recording (MER).2,5-10 MER can be used to map out the target nucleus and define the best location for lead placement. (deepdyve.com)
  • The increase in the roughness of the microelectrodes surface was imaged using digital holographic microscopy and electron microscopy. (epfl.ch)
  • a silicon nitride passivation permits a selective exposure of microelectrodes to electrolyte. (spie.org)
  • This report focuses on the global key players (Abbott Point of Care, Thermo Fisher Scientific, Alfa Wassermann, Van London-Phoenix Company, Beckman Coulter, Microelectrodes and F. Hoffmann-La Roche) performing at a global level, to explain, define and analyze the multiple aspects of the Ion-Selective Clinical Lab Analyzers market. (pharmiweb.com)
  • Transport of K + by the lower, main and distal segments of the Malpighian tubules of Drosophila melanogaster was analyzed using self-referencing K + -selective microelectrodes. (biologists.org)
  • Burchiel, K & Winfree, CJ 2005, ' Correspondence of microelectrode mapping with magnetic resonance imaging for subthalamic nucleus procedures: Commentary ', Surgical Neurology , vol. 63, no. 3, pp. 253. (elsevier.com)