A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.
Cation-transporting proteins that utilize the energy of ATP hydrolysis for the transport of CALCIUM. They differ from CALCIUM CHANNELS which allow calcium to pass through a membrane without the use of energy.
Calcium-transporting ATPases that catalyze the active transport of CALCIUM into the SARCOPLASMIC RETICULUM vesicles from the CYTOPLASM. They are primarily found in MUSCLE CELLS and play a role in the relaxation of MUSCLES.
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.
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 tetrameric calcium release channel in the SARCOPLASMIC RETICULUM membrane of SMOOTH MUSCLE CELLS, acting oppositely to SARCOPLASMIC RETICULUM CALCIUM-TRANSPORTING ATPASES. It is important in skeletal and cardiac excitation-contraction coupling and studied by using RYANODINE. Abnormalities are implicated in CARDIAC ARRHYTHMIAS and MUSCULAR DISEASES.
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.
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.
Acidic protein found in SARCOPLASMIC RETICULUM that binds calcium to the extent of 700-900 nmoles/mg. It plays the role of sequestering calcium transported to the interior of the intracellular vesicle.
A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.
Contractile tissue that produces movement in animals.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
Proteins to which calcium ions are bound. They can act as transport proteins, regulator proteins, or activator proteins. They typically contain EF HAND MOTIFS.
Contractile activity of the MYOCARDIUM.
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.
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.
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.
An inorganic dye used in microscopy for differential staining and as a diagnostic reagent. In research this compound is used to study changes in cytoplasmic concentrations of calcium. Ruthenium red inhibits calcium transport through membrane channels.
The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.
The rate dynamics in chemical or physical systems.
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.
An electrogenic ion exchange protein that maintains a steady level of calcium by removing an amount of calcium equal to that which enters the cells. It is widely distributed in most excitable membranes, including the brain and heart.
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.
A sesquiterpene lactone found in roots of THAPSIA. It inhibits CA(2+)-TRANSPORTING ATPASE mediated uptake of CALCIUM into SARCOPLASMIC RETICULUM.
A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.
A process fundamental to muscle physiology whereby an electrical stimulus or action potential triggers a myocyte to depolarize and contract. This mechanical muscle contraction response is regulated by entry of calcium ions into the cell.
A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.
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.
The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and nonexcitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.
Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
A potent local anesthetic of the ester type used for surface and spinal anesthesia.
The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.
A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016).
Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.
The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .
Skeletal muscle relaxant that acts by interfering with excitation-contraction coupling in the muscle fiber. It is used in spasticity and other neuromuscular abnormalities. Although the mechanism of action is probably not central, dantrolene is usually grouped with the central muscle relaxants.
Derivatives of OXALIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that are derived from the ethanedioic acid structure.
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
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)
The hollow, muscular organ that maintains the circulation of the blood.
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.
Rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia.
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 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).
Various physiological or molecular disturbances that impair ENDOPLASMIC RETICULUM function. It triggers many responses, including UNFOLDED PROTEIN RESPONSE, which may lead to APOPTOSIS; and AUTOPHAGY.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
A metallic element with the atomic symbol V, atomic number 23, and atomic weight 50.94. It is used in the manufacture of vanadium steel. Prolonged exposure can lead to chronic intoxication caused by absorption usually via the lungs.
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.
5,5'-Nitrilodibarbituric acid ammonium derivative. Used as an indicator for complexometric titrations.
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.
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)
Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.
Unstable isotopes of calcium that decay or disintegrate emitting radiation. Ca atoms with atomic weights 39, 41, 45, 47, 49, and 50 are radioactive calcium isotopes.
Compounds with three aromatic rings in linear arrangement with an OXYGEN in the center ring.
Benzopyrroles with the nitrogen at the number one carbon adjacent to the benzyl portion, in contrast to ISOINDOLES which have the nitrogen away from the six-membered ring.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
A type of endoplasmic reticulum (ER) where polyribosomes are present on the cytoplasmic surfaces of the ER membranes. This form of ER is prominent in cells specialized for protein secretion and its principal function is to segregate proteins destined for export or intracellular utilization.
A class of organic compounds that contains a naphthalene moiety linked to a sulfonic acid salt or ester.
Oxyvanadium ions in various states of oxidation. They act primarily as ion transport inhibitors due to their inhibition of Na(+)-, K(+)-, and Ca(+)-ATPase transport systems. They also have insulin-like action, positive inotropic action on cardiac ventricular muscle, and other metabolic effects.
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.
Cationic ionophore antibiotic obtained from Streptomyces lasaliensis that, among other effects, dissociates the calcium fluxes in muscle fibers. It is used as a coccidiostat, especially in poultry.
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.
Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.
Fluorescent probe capable of being conjugated to tissue and proteins. It is used as a label in fluorescent antibody staining procedures as well as protein- and amino acid-binding techniques.
Inorganic salts of phosphoric acid.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)
Elements of limited time intervals, contributing to particular results or situations.
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 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.
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.
Measurement of the intensity and quality of fluorescence.
A photoprotein isolated from the bioluminescent jellyfish Aequorea. It emits visible light by an intramolecular reaction when a trace amount of calcium ion is added. The light-emitting moiety in the bioluminescence reaction is believed to be 2-amino-3-benzyl-5-(p-hydroxyphenyl)pyrazine (AF-350).
Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.
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.
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.
A class of drugs that act by selective inhibition of calcium influx through cellular membranes.
The hemodynamic and electrophysiological action of the HEART VENTRICLES.
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.
An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.
Use of electric potential or currents to elicit biological responses.
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).
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.
Intracellular receptors that bind to INOSITOL 1,4,5-TRISPHOSPHATE and play an important role in its intracellular signaling. Inositol 1,4,5-trisphosphate receptors are calcium channels that release CALCIUM in response to increased levels of inositol 1,4,5-trisphosphate in the CYTOPLASM.
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.
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.
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.
A family of immunophilin proteins that bind to the immunosuppressive drugs TACROLIMUS (also known as FK506) and SIROLIMUS. EC 5.2.1.-
Lanthanum. The prototypical element in the rare earth family of metals. It has the atomic symbol La, atomic number 57, and atomic weight 138.91. Lanthanide ion is used in experimental biology as a calcium antagonist; lanthanum oxide improves the optical properties of glass.
A type of glycoside widely distributed in plants. Each consists of a sapogenin as the aglycone moiety, and a sugar. The sapogenin may be a steroid or a triterpene and the sugar may be glucose, galactose, a pentose, or a methylpentose.
A type of endoplasmic reticulum lacking associated ribosomes on the membrane surface. It exhibits a wide range of specialized metabolic functions including supplying enzymes for steroid synthesis, detoxification, and glycogen breakdown. In muscle cells, smooth endoplasmic reticulum is called SARCOPLASMIC RETICULUM.
A multifunctional calcium-calmodulin-dependent protein kinase subtype that occurs as an oligomeric protein comprised of twelve subunits. It differs from other enzyme subtypes in that it lacks a phosphorylatable activation domain that can respond to CALCIUM-CALMODULIN-DEPENDENT PROTEIN KINASE KINASE.
A class of compounds composed of repeating 5-carbon units of HEMITERPENES.
Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
The process of cleaving a chemical compound by the addition of a molecule of water.
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 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.
A multifunctional protein that is found primarily within membrane-bound organelles. In the ENDOPLASMIC RETICULUM it binds to specific N-linked oligosaccharides found on newly-synthesized proteins and functions as a MOLECULAR CHAPERONE that may play a role in PROTEIN FOLDING or retention and degradation of misfolded proteins. In addition calreticulin is a major storage form for CALCIUM and functions as a calcium-signaling molecule that can regulate intracellular calcium HOMEOSTASIS.
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)
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
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.
Agents that increase calcium influx into calcium channels of excitable tissues. This causes vasoconstriction in VASCULAR SMOOTH MUSCLE and/or CARDIAC MUSCLE cells as well as stimulation of insulin release from pancreatic islets. Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders. They have been used primarily in experimental studies in cell and tissue culture.
A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.
Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.
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 fluorescent calcium chelating agent which is used to study intracellular calcium in tissues.
A 12-KDa tacrolimus binding protein that is found associated with and may modulate the function of calcium release channels. It is a peptidyl-prolyl cis/trans isomerase which is inhibited by both tacrolimus (commonly called FK506) and SIROLIMUS.
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 ability of a substrate to allow the passage of ELECTRONS.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
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.
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.
The family of true frogs of the order Anura. The family occurs worldwide except in Antarctica.
Enlargement of the HEART, usually indicated by a cardiothoracic ratio above 0.50. Heart enlargement may involve the right, the left, or both HEART VENTRICLES or HEART ATRIA. Cardiomegaly is a nonspecific symptom seen in patients with chronic systolic heart failure (HEART FAILURE) or several forms of CARDIOMYOPATHIES.
A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels.
Drugs that selectively bind to and activate beta-adrenergic receptors.
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.
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.
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.
5'-Adenylic acid, monoanhydride with imidodiphosphoric acid. An analog of ATP, in which the oxygen atom bridging the beta to the gamma phosphate is replaced by a nitrogen atom. It is a potent competitive inhibitor of soluble and membrane-bound mitochondrial ATPase and also inhibits ATP-dependent reactions of oxidative phosphorylation.
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.
Mitochondria of skeletal and smooth muscle. It does not include myocardial mitochondria for which MITOCHONDRIA, HEART is available.
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)
Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.
A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (VENTRICULAR DYSFUNCTION), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as MYOCARDIAL INFARCTION.
Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.
A salt used to replenish calcium levels, as an acid-producing diuretic, and as an antidote for magnesium poisoning.
A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 3.4.21.4.
Organic nitrogenous bases. Many alkaloids of medical importance occur in the animal and vegetable kingdoms, and some have been synthesized. (Grant & Hackh's Chemical Dictionary, 5th ed)
Protein-lipid combinations abundant in brain tissue, but also present in a wide variety of animal and plant tissues. In contrast to lipoproteins, they are insoluble in water, but soluble in a chloroform-methanol mixture. The protein moiety has a high content of hydrophobic amino acids. The associated lipids consist of a mixture of GLYCEROPHOSPHATES; CEREBROSIDES; and SULFOGLYCOSPHINGOLIPIDS; while lipoproteins contain PHOSPHOLIPIDS; CHOLESTEROL; and TRIGLYCERIDES.
The chambers of the heart, to which the BLOOD returns from the circulation.
A phenol obtained from thyme oil or other volatile oils used as a stabilizer in pharmaceutical preparations, and as an antiseptic (antibacterial or antifungal) agent. It was formerly used as a vermifuge.
A nonfluorescent reagent for the detection of primary amines, peptides and proteins. The reaction products are highly fluorescent.
A silver salt with powerful germicidal activity. It has been used topically to prevent OPHTHALMIA NEONATORUM.
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)
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.
The relationship between the dose of an administered drug and the response of the organism to the drug.
A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.
Semidomesticated variety of European polecat much used for hunting RODENTS and/or RABBITS and as a laboratory animal. It is in the subfamily Mustelinae, family MUSTELIDAE.
Organic derivatives of thiocyanic acid which contain the general formula R-SCN.
Compounds containing the -SH radical.
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.
A group of elements that include SCANDIUM; YTTRIUM; and the LANTHANOID SERIES ELEMENTS. Historically, the rare earth metals got their name from the fact that they were never found in their pure elemental form, but as an oxide. In addition they were very difficult to purify. They are not truly rare and comprise about 25% of the metals in the earth's crust.
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.
The sum of the weight of all the atoms in a molecule.
Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.
An anionic compound that is used as a reagent for determination of potassium, ammonium, rubidium, and cesium ions. It also uncouples oxidative phosphorylation and forms complexes with biological materials, and is used in biological assays.
Carbon-containing phosphoric acid derivatives. Included under this heading are compounds that have CARBON atoms bound to one or more OXYGEN atoms of the P(=O)(O)3 structure. Note that several specific classes of endogenous phosphorus-containing compounds such as NUCLEOTIDES; PHOSPHOLIPIDS; and PHOSPHOPROTEINS are listed elsewhere.
Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).
A state arrived at through prolonged and strong contraction of a muscle. Studies in athletes during prolonged submaximal exercise have shown that muscle fatigue increases in almost direct proportion to the rate of muscle glycogen depletion. Muscle fatigue in short-term maximal exercise is associated with oxygen lack and an increased level of blood and muscle lactic acid, and an accompanying increase in hydrogen-ion concentration in the exercised muscle.
A reagent commonly used in biochemical studies as a protective agent to prevent the oxidation of SH (thiol) groups and for reducing disulphides to dithiols.
The processes whereby the internal environment of an organism tends to remain balanced and stable.
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.
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
An ionophorous, polyether antibiotic from Streptomyces chartreusensis. It binds and transports CALCIUM and other divalent cations across membranes and uncouples oxidative phosphorylation while inhibiting ATPase of rat liver mitochondria. The substance is used mostly as a biochemical tool to study the role of divalent cations in various biological systems.
A strong dicarboxylic acid occurring in many plants and vegetables. It is produced in the body by metabolism of glyoxylic acid or ascorbic acid. It is not metabolized but excreted in the urine. It is used as an analytical reagent and general reducing agent.
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.
Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.
A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.
Transport proteins that carry specific substances in the blood or across cell membranes.
Intracellular messenger formed by the action of phospholipase C on phosphatidylinositol 4,5-bisphosphate, which is one of the phospholipids that make up the cell membrane. Inositol 1,4,5-trisphosphate is released into the cytoplasm where it releases calcium ions from internal stores within the cell's endoplasmic reticulum. These calcium ions stimulate the activity of B kinase or calmodulin.
A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents. They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358)
Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.
A phenothiazine with actions similar to CHLORPROMAZINE. It is used as an antipsychotic and an antiemetic.
Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).
Established cell cultures that have the potential to propagate indefinitely.
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)
The nonstriated involuntary muscle tissue of blood vessels.
The second stomach of ruminants. It lies almost in the midline in the front of the abdomen, in contact with the liver and diaphragm and communicates freely with the RUMEN via the ruminoreticular orifice. The lining of the reticulum is raised into folds forming a honeycomb pattern over the surface. (From Concise Veterinary Dictionary, 1988)
The mitochondria of the myocardium.
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.
Magnesium chloride. An inorganic compound consisting of one magnesium and two chloride ions. The compound is used in medicine as a source of magnesium ions, which are essential for many cellular activities. It has also been used as a cathartic and in alloys.
A group of enzymes that are dependent on CYCLIC AMP and catalyze the phosphorylation of SERINE or THREONINE residues on proteins. Included under this category are two cyclic-AMP-dependent protein kinase subtypes, each of which is defined by its subunit composition.
Terbium. An element of the rare earth family of metals. It has the atomic symbol Tb, atomic number 65, and atomic weight 158.92.
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
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.
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.
One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
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.
Inorganic or organic compounds that contain boron as an integral part of the molecule.
A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.
The fluid inside CELLS.
The repeating contractile units of the MYOFIBRIL, delimited by Z bands along its length.
A sulfhydryl reagent that is widely used in experimental biochemical studies.
The 5-beta-reduced isomer of ANDROSTERONE. Etiocholanolone is a major metabolite of TESTOSTERONE and ANDROSTENEDIONE in many mammalian species including humans. It is excreted in the URINE.
A cellular response to environmental insults that cause disruptions in PROTEIN FOLDING and/or accumulation of defectively folded protein in the ENDOPLASMIC RETICULUM. It consists of a group of regulatory cascades that are triggered as a response to altered levels of calcium and/or the redox state of the endoplasmic reticulum. Persistent activation of the unfolded protein response leads to the induction of APOPTOSIS.
Methods of preparing tissue for examination and study of the origin, structure, function, or pathology.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

A novel interaction mechanism accounting for different acylphosphatase effects on cardiac and fast twitch skeletal muscle sarcoplasmic reticulum calcium pumps. (1/4498)

In cardiac and skeletal muscle Ca2+ translocation from cytoplasm into sarcoplasmic reticulum (SR) is accomplished by different Ca2+-ATPases whose functioning involves the formation and decomposition of an acylphosphorylated phosphoenzyme intermediate (EP). In this study we found that acylphosphatase, an enzyme well represented in muscular tissues and which actively hydrolyzes EP, had different effects on heart (SERCA2a) and fast twitch skeletal muscle SR Ca2+-ATPase (SERCA1). With physiological acylphosphatase concentrations SERCA2a exhibited a parallel increase in the rates of both ATP hydrolysis and Ca2+ transport; in contrast, SERCA1 appeared to be uncoupled since the stimulation of ATP hydrolysis matched an inhibition of Ca2+ pump. These different effects probably depend on phospholamban, which is associated with SERCA2a but not SERCA1. Consistent with this view, the present study suggests that acylphosphatase-induced stimulation of SERCA2a, in addition to an enhanced EP hydrolysis, may be due to a displacement of phospholamban, thus to a removal of its inhibitory effect.  (+info)

Expression of skeletal muscle sarcoplasmic reticulum calcium-ATPase is reduced in rats with postinfarction heart failure. (2/4498)

OBJECTIVE: To determine whether heart failure in rats is associated with altered expression of the skeletal muscle sarcoplasmic reticulum Ca2+-ATPase (SERCA). METHODS: SERCA protein and mRNA were examined in the soleus muscles of eight female rats with heart failure induced by coronary artery ligation, six weeks after the procedure (mean (SEM) left ventricular end diastolic pressure 20.4 (2.2) mm Hg) and in six sham operated controls by western and northern analyses, respectively. RESULTS: SERCA-2a isoform protein was reduced by 16% (112 000 (4000) v 134 000 (2000) arbitrary units, p < 0.001), and SERCA-2a messenger RNA was reduced by 59% (0.24 (0. 06) v 0.58 (0.02) arbitrary units, p < 0.001). Although rats with heart failure had smaller muscles (0.54 mg/g v 0.66 mg/g body weight), no difference in locomotor activity was observed. CONCLUSIONS: These results may explain the previously documented abnormalities in calcium handling in skeletal muscle from animals with the same model of congestive heart failure, and could be responsible for the accelerated muscle fatigue characteristic of patients with heart failure.  (+info)

Ca-releasing action of beta, gamma-methylene adenosine triphosphate on fragmented sarcoplasmic reticulum. (3/4498)

beta,gamma-Methylene adenosine triphosphate (AMPOPCP) has two effects on fragmented sarcoplasmic reticulum (FSR), i.e., inhibition of the rate of Ca uptake and the induction of Ca release from FSR filled with Ca. The Ca release brought about by AMPOPCP has many features in common with the mechanism of Ca-induced Ca release: i) it is inhibited by 10 mM procaine; ii) the amount of Ca release increases with increase in the extent of saturation of FSR with Ca; iii) increase of the Ca concentration in the extent of saturation of FSR with Ca; iii) increase of the Ca concentration in the medium facilitates the release of Ca. However, no facilitation of Ca release upon decrease of Mg concentration in the medium is observable. AMPOPCP and caffeine potentiate each other remarkably in their Ca-releasing action, irrespective of the kind of substrate. From the mode of action of AMPOPCP on the rate of Ca uptake, the amount of phosphorylated intermediate (EP), and the effect on Sr release, it is suggested that the state of the FSR-ATP complex is crucial for Ca-induced Ca release.  (+info)

Mutations of Arg198 in sarcoplasmic reticulum Ca2+-ATPase cause inhibition of hydrolysis of the phosphoenzyme intermediate formed from inorganic phosphate. (4/4498)

Arg198 of sarcoplasmic reticulum Ca2+-ATPase was substituted with lysine, glutamine, glutamic acid, alanine, and isoleucine by site-directed mutagenesis. Kinetic analysis was performed with microsomal membranes isolated from COS-1 cells which were transfected with the mutated cDNAs. The rate of dephosphorylation of the ADP-insensitive phosphoenzyme was determined by first phosphorylating the Ca2+-ATPase with 32Pi and then diluting the sample with non-radioactive Pi. This rate was reduced substantially in the mutant R198Q, more strongly in the mutants R198A and R1981, and most strongly in the mutant R198E, but to a much lesser extent in R198K. The reduction in the rate of dephosphorylation was consistent with the observed decrease in the turnover rate of the Ca2+-ATPase accompanied by the steady-state accumulation of the ADP-insensitive phosphoenzyme formed from ATP. These results indicate that the positive charge and high hydrophilicity of Arg198 are critical for rapid hydrolysis of the ADP-insensitive phosphoenzyme.  (+info)

A repetitive mode of activation of discrete Ca2+ release events (Ca2+ sparks) in frog skeletal muscle fibres. (5/4498)

1. Ca2+ release events (Ca2+ 'sparks'), which are believed to arise from the opening of a sarcoplasmic reticulum (SR) Ca2+ release channel or a small cluster of such channels that act as a release unit, have been measured in single, frog (Rana pipiens) skeletal muscle fibres. 2. Under conditions of extremely low rates of occurrence of Ca2+ sparks we observed, within individual identified triads, repetitive Ca2+ release events which occurred at a frequency more than 100-fold greater than the prevailing average event rate. Repetitive sparks were recorded during voltage-clamp test depolarizations after a brief (0.3-2 s) repriming interval in fibres held at 0 mV and in chronically depolarized, 'notched' fibres. 3. These repetitive events are likely to arise from the re-opening of the same SR Ca2+ release channel or release unit operating in a repetitive gating mode ('rep-mode'), rather than from the random activation of multiple, independent channels or release units within a triad. A train of rep-mode events thus represents a series of Ca2+ sparks arising from a single location within the fibre. Rep-mode events are activated among different triads in a random manner after brief repriming. The frequency of repetitive events among all identified events during voltage-clamp depolarization to 0 mV after brief repriming was 3.9 +/- 1.3 %. The occurrence of repetitive events was not related to exposure of the fibre to laser illumination. 4. The events observed within a rep-mode train exhibited a relatively uniform amplitude. Analysis of intervals between identified events in triads exhibiting rep-mode trains indicated similar variations of fluorescence as in neighbouring, quiescent triads, suggesting there was not a significant number of small, unidentified events at the triads exhibiting rep-mode activity. 5. The distribution of rep-mode interspark intervals exhibited a paucity of events at short intervals, consistent with the need for recovery from inactivation before activation of the next event in a repetitive train. The mean interspark interval of repetitive sparks during voltage-clamp depolarizations was 88 +/- 5 ms, and was independent of membrane potential. 6. The individual Ca2+ sparks within a rep-mode train were similar in average amplitude and spatiotemporal extent to singly occurring sparks, suggesting a common mechanism for termination of the channel opening(s) underlying both types of events. The average properties of the sparks did not vary during a train. The relative amplitude of a spark within a rep-mode was not correlated with its rise time. 7. Repetitive Ca2+ release events represent a mode of gating of SR Ca2+ release channels which may be significant during long depolarizations and which may be influenced by the biochemical state of the SR ryanodine receptor Ca2+ release channels.  (+info)

Local control models of cardiac excitation-contraction coupling. A possible role for allosteric interactions between ryanodine receptors. (6/4498)

In cardiac muscle, release of activator calcium from the sarcoplasmic reticulum occurs by calcium- induced calcium release through ryanodine receptors (RyRs), which are clustered in a dense, regular, two-dimensional lattice array at the diad junction. We simulated numerically the stochastic dynamics of RyRs and L-type sarcolemmal calcium channels interacting via calcium nano-domains in the junctional cleft. Four putative RyR gating schemes based on single-channel measurements in lipid bilayers all failed to give stable excitation-contraction coupling, due either to insufficiently strong inactivation to terminate locally regenerative calcium-induced calcium release or insufficient cooperativity to discriminate against RyR activation by background calcium. If the ryanodine receptor was represented, instead, by a phenomenological four-state gating scheme, with channel opening resulting from simultaneous binding of two Ca2+ ions, and either calcium-dependent or activation-linked inactivation, the simulations gave a good semiquantitative accounting for the macroscopic features of excitation-contraction coupling. It was possible to restore stability to a model based on a bilayer-derived gating scheme, by introducing allosteric interactions between nearest-neighbor RyRs so as to stabilize the inactivated state and produce cooperativity among calcium binding sites on different RyRs. Such allosteric coupling between RyRs may be a function of the foot process and lattice array, explaining their conservation during evolution.  (+info)

Cellular mechanisms of altered contractility in the hypertrophied heart: big hearts, big sparks. (7/4498)

To investigate the cellular mechanisms for altered Ca2+ homeostasis and contractility in cardiac hypertrophy, we measured whole-cell L-type Ca2+ currents (ICa,L), whole-cell Ca2+ transients ([Ca2+]i), and Ca2+ sparks in ventricular cells from 6-month-old spontaneously hypertensive rats (SHRs) and from age- and sex-matched Wistar-Kyoto and Sprague-Dawley control rats. By echocardiography, SHR hearts had cardiac hypertrophy and enhanced contractility (increased fractional shortening) and no signs of heart failure. SHR cells had a voltage-dependent increase in peak [Ca2+]i amplitude (at 0 mV, 1330+/-62 nmol/L [SHRs] versus 836+/-48 nmol/L [controls], P<0.05) that was not associated with changes in ICa,L density or kinetics, resting [Ca2+]i, or Ca2+ content of the sarcoplasmic reticulum (SR). SHR cells had increased time of relaxation. Ca2+ sparks from SHR cells had larger average amplitudes (173+/-192 nmol/L [SHRs] versus 109+/-64 nmol/L [control]; P<0.05), which was due to redistribution of Ca2+ sparks to a larger amplitude population. This change in Ca2+ spark amplitude distribution was not associated with any change in the density of ryanodine receptors, calsequestrin, junctin, triadin 1, Ca2+-ATPase, or phospholamban. Therefore, SHRs with cardiac hypertrophy have increased contractility, [Ca2+]i amplitude, time to relaxation, and average Ca2+ spark amplitude ("big sparks"). Importantly, big sparks occurred without alteration in the trigger for SR Ca2+ release (ICa,L), SR Ca2+ content, or the expression of several SR Ca2+-cycling proteins. Thus, cardiac hypertrophy in SHRs is linked with an alteration in the coupling of Ca2+ entry through L-type Ca2+ channels and the release of Ca2+ from the SR, leading to big sparks and enhanced contractility. Alterations in the microdomain between L-type Ca2+ channels and SR Ca2+ release channels may underlie the changes in Ca2+ homeostasis observed in cardiac hypertrophy. Modulation of SR Ca2+ release may provide a new therapeutic strategy for cardiac hypertrophy and for its progression to heart failure and sudden death.  (+info)

The sarcoplasmic reticulum and the Na+/Ca2+ exchanger both contribute to the Ca2+ transient of failing human ventricular myocytes. (8/4498)

Our objective was to determine the respective roles of the sarcoplasmic reticulum (SR) and the Na+/Ca2+ exchanger in the small, slowly decaying Ca2+ transients of failing human ventricular myocytes. Left ventricular myocytes were isolated from explanted hearts of patients with severe heart failure (n=18). Cytosolic Ca2+, contraction, and action potentials were measured by using indo-1, edge detection, and patch pipettes, respectively. Selective inhibitors of SR Ca2+ transport (thapsigargin) and reverse-mode Na+/Ca2+ exchange activity (No. 7943, Kanebo Ltd) were used to define the respective contribution of these processes to the Ca2+ transient. Ca2+ transients and contractions induced by action potentials (AP transients) at 0.5 Hz exhibited phasic and tonic components. The duration of the tonic component was determined by the action potential duration. Ca2+ transients induced by caffeine (Caf transients) exhibited only a phasic component with a rapid rate of decay that was dependent on extracellular Na+. The SR Ca2+-ATPase inhibitor thapsigargin abolished the phasic component of the AP Ca2+ transient and of the Caf transient but had no significant effect on the tonic component of the AP transient. The Na+/Ca2+ exchange inhibitor No. 7943 eliminated the tonic component of the AP transient and reduced the magnitude of the phasic component. In failing human myocytes, Ca2+ transients and contractions exhibit an SR-related, phasic component and a slow, reverse-mode Na+/Ca2+ exchange-related tonic component. These findings suggest that Ca2+ influx via reverse-mode Na+/Ca2+ exchange during the action potential may contribute to the slow decay of the Ca2+ transient in failing human myocytes.  (+info)

In previous efforts to characterize sarcoplasmic reticulum function in human muscles, it has not been possible to distinguish the relative contributions of fast-twitch and slow-twitch fibers. In this study, we have used light scattering and 45Ca to monitor Ca accumulation by the sarcoplasmic reticulum of isolated, chemically skinned human muscle fibers in the presence and absence of oxalate. Oxalate (5 mM) increased the capacity for Ca accumulation by a factor of 35 and made it possible to assess both rate of Ca uptake and relative sarcoplasmic reticulum volume in individual fibers. At a fixed ionized Ca concentration, the rate and maximal capacity (an index of sarcoplasmic reticulum volume) both varied over a wide range, but fibers fell into two distinct groups (fast and slow). Between the two groups, there was a 2- to 2.5-fold difference in oxalate-supported Ca uptake rates, but no difference in average sarcoplasmic reticulum volumes. Intrinsic differences in sarcoplasmic reticulum function ...
TY - JOUR. T1 - The role of ganglioside GM3 in the modulation of conformation and activity of sarcoplasmic reticulum CA2+-ATPase. AU - Yang, F. Y.. AU - Wang, L. H.. AU - Yang, X. Y.. AU - Tsui, Z. C.. AU - Tu, Yaping. PY - 1997/10. Y1 - 1997/10. N2 - Rabbit sarcoplasmic reticulum does contain trace amounts of gangliosides, and the main species is GM3. Incorporation of GM3 into the SR vesicles or addition of it to the soybean phospholipid used for reconstitution of proteoliposomes obviously increased ATP hydrolysis, as well as, Ca2+ uptake activity of sarcoplasmic reticulum Ca2+-ATPase. Conformation changes of Ca2+-ATPase induced by GM3 were also observed by circular dichroism, intrinsic fluorescence and fluorescence quenching measurements.. AB - Rabbit sarcoplasmic reticulum does contain trace amounts of gangliosides, and the main species is GM3. Incorporation of GM3 into the SR vesicles or addition of it to the soybean phospholipid used for reconstitution of proteoliposomes obviously increased ...
A dysfunctioning of Ca2+ pump ATPase in the sarcoplasmic reticulum in vascular smooth muscle has been proposed as a contributing factor for the development of genetic hypertension. In this study, we determined whether in vitro inhibition of the sarcoplasmic reticulum Ca2+ pump in vascular smooth muscle tissues and cultured cells isolated from aortas of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats would elicit the known alterations of contractile function and cell growth. We found the following common vascular effects of thapsigargin and cyclopiazonic acid, which are known to be selective inhibitors of sarcoplasmic reticulum Ca(2+)-ATPase in a number of tissues including smooth muscle: (1) Both sarcoplasmic reticulum Ca2+ pump inhibitors diminished agonist-induced transient contraction in Ca(2+)-free medium (ie, contraction due to intracellular release of Ca2+) and enhanced nifedipine-sensitive contraction on readmission of Ca2+ (ie, Ca2+ influx via L-type channels); and (2) ...
TY - JOUR. T1 - Nitric oxide-dependent activation of CaMKII increases diastolic sarcoplasmic reticulum calcium release in cardiac myocytes in response to adrenergic stimulation. AU - Curran, Jerry. AU - Tang, Lifei. AU - Roof, Steve R.. AU - Velmurugan, Sathya. AU - Millard, Ashley. AU - Shonts, Stephen. AU - Wang, Honglan. AU - Santiago, Demetrio. AU - Ahmad, Usama. AU - Perryman, Matthew. AU - Bers, Donald M. AU - Mohler, Peter J.. AU - Ziolo, Mark T.. AU - Shannon, Thomas R.. PY - 2014/2/3. Y1 - 2014/2/3. N2 - Spontaneous calcium waves in cardiac myocytes are caused by diastolic sarcoplasmic reticulum release (SR Ca2+ leak) through ryanodine receptors. Beta-adrenergic (β-AR) tone is known to increase this leak through the activation of Ca-calmodulin-dependent protein kinase (CaMKII) and the subsequent phosphorylation of the ryanodine receptor. When b-AR drive is chronic, as observed in heart failure, this CaMKII-dependent effect is exaggerated and becomes potentially arrhythmogenic. Recent ...
Shop Junctional sarcoplasmic reticulum protein ELISA Kit, Recombinant Protein and Junctional sarcoplasmic reticulum protein Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
It has been proposed that breakdown of the excitation-contraction coupling system plays a pivotal role in myocardial dysfunction during the course of acute ischemia. We tested this hypothesis by characterizing the function of the sarcoplasmic reticulum at pH 7.1 and 6.4 after 7.5, 15, and 30 minutes of canine normothermic global ischemia. At pH 7.1, whole heart homogenate sarcoplasmic reticulum demonstrated a 49% depression of oxalate-supported calcium uptake at 7.5 minutes of ischemia, which progressed to 85% at 30 minutes of ischemia. At pH 6.4, control homogenate calcium uptake rates were significantly depressed, accompanied by a further depression in the ischemic groups. Isolated sarcoplasmic reticulum calcium uptake mirrored the effects of the whole heart homogenate. Calcium-stimulated magnesium-dependent ATPase (calcium-ATPase) activity was significantly depressed by both ischemia and acidosis, with a decrease in the coupling ratio (mumol calcium/mumol ATP) at 15 and 30 minutes of ...
Calcium uptake was measured in homogenates and microsomal preparations enriched in sarcoplasmic reticulum vesicles isolated from hearts of hypertrophic (BIO 14.6) and dilated (BIO 53.58) cardiomyopathic as well as control (F1B) Syrian hamsters at 3, 7, 9, and 11 months of age. Calcium uptake studies were done using the Millipore filtration technique under conditions known to restrict transport to the sarcoplasmic reticulum. Steady-state calcium uptake capacity was used as a measure of the relative amounts of sarcoplasmic reticulum in homogenates prepared from individual hearts. At 3 months of age, there were no differences in calcium uptake in homogenates from control or myopathic hearts. However, by 9 months, although calcium uptake of homogenates from control and hypertrophic hearts was the same, calcium uptake by homogenates from dilated hearts was significantly depressed both in initial rate and capacity. Similar trends were seen in the microsomal vesicle preparations, but the decrease in ...
Localized, transient elevations in cytosolic Ca2+, known as Ca2+ sparks, caused by Ca2+ release from sarcoplasmic reticulum, are thought to trigger the opening of large conductance Ca2+-activated potassium channels in the plasma membrane resulting in spontaneous transient outward currents (STOCs) in smooth muscle cells. But the precise relationships between Ca2+ concentration within the sarcoplasmic reticulum and a Ca2+ spark and that between a Ca2+ spark and a STOC are not well defined or fully understood. To address these problems, we have employed two approaches using single patch-clamped smooth muscle cells freshly dissociated from toad stomach: a high speed, wide-field imaging system to simultaneously record Ca2+ sparks and STOCs, and a method to simultaneously measure free global Ca2+ concentration in the sarcoplasmic reticulum ([Ca2+]SR) and in the cytosol ([Ca2+]CYTO) along with STOCs. At a holding potential of 0 mV, cells displayed Ca2+ sparks and STOCs. Ca2+ sparks were associated with STOCs;
TY - JOUR. T1 - The regulation of ATPase-ATPase interactions in sarcoplasmic reticulum membrane. I. The effects of Ca2+, ATP, and inorganic phosphate.. AU - Dux, L.. AU - Martonosi, A.. PY - 1983/10/10. Y1 - 1983/10/10. N2 - Two-dimensional crystalline arrays of Ca2+-ATPase molecules develop after treatment of sarcoplasmic reticulum vesicles with Na3VO4 in calcium-free medium (Dux, L., and Martonosi, A. (1983) J. Biol. Chem. 258, 2599-2603). The formation of Ca2+-ATPase crystals is inhibited by Ca2+ (2 microM), or ATP (5 mM), but not by ADP, 5-adenylylimidodiphosphate, or adenylylmethylenediphosphonate. ATPase crystals did not form at 37 degrees C and exposure of preformed crystals to 37 degrees C for 1 h caused the disappearance of crystal lattice. Inorganic orthophosphate (1 mM at pH 6.0) promoted the formation of a distinct crystal form of Ca2+-ATPase, which was different from that produced by Na3VO4. These observations indicate that Ca2+, ATP, inorganic phosphate, pH, and temperature ...
is a human gene associated with the release of Calcium ions from the sarcoplasmic reticulum triggering muscular contraction through calcium-induced calcium release ... It is a transmembrane protein on the sarcoplasmic reticulum due to a well defined hydrophobic section, and it forms a quaternary complex with Ryanodine receptors (RyR ... The luminal (inner compartment of the sarcoplasmic reticulum) section of Triadin has areas of highly charged amino acid residues that act as luminal Ca2+ receptors ...
TY - JOUR. T1 - Ca2+ handling and sarcoplasmic reticulum Ca2+ content in isolated failing and nonfailing human myocardium. AU - Pieske, Burkert. AU - Maier, Lars S.. AU - Bers, Donald M. AU - Hasenfuss, Gerd. PY - 1999/7/9. Y1 - 1999/7/9. N2 - Disturbed sarcoplasmic reticulum (SR) Ca2+ content may underlie the altered force-frequency and postrest contractile behavior in failing human myocardium. We used rapid cooling contractures (RCCs) to assess SR Ca2+ content in ventricular muscle strips isolated from nonfailing and end-stage failing human hearts. With an increase in rest intervals (1 to 240 s; 37°C), nonfailing human myocardium (n=7) exhibited a parallel increase in postrest twitch force (at 240 s by 121±44%; P,0.05) and RCC amplitude (by 69±53%; P,0.05). In contrast, in failing myocardium (n=30), postrest twitch force decreased at long rest intervals and RCC amplitude declined monotonically with rest (by 25±9% and 53±9%, respectively; P,0.05). With an increase in stimulation ...
TY - JOUR. T1 - Sarcoplasmic reticulum Ca2+ regulatory protein gene expression in human right atrium under hemodynamic overload. AU - Sadamatsu, Kenji. AU - Urabe, Yoshitoshi. AU - Tsutsui, Hiroyuki. AU - Tagawa, Hirofumi. AU - Maruoka, Fumio. AU - Igarashi-Saito, Keiko. AU - Takeda, Kotaro. AU - Kawachi, Yoshito. AU - Yasui, Hisataka. AU - Takeshita, Akira. PY - 1999/1/1. Y1 - 1999/1/1. N2 - Sarcoplasmic reticulum (SR) Ca2+-adenosine triphosphatase (ATPase) mRNA expression is reduced in the failing human myocardium. However, it is not known whether SR Ca2+-regulatory protein gene expression is altered in human myocardial tissue subjected to pressure overload or volume overload. We sought to determine whether SR Ca2+-regulatory protein gene expression is altered in human atrial tissue subjected to mechanical overload. We obtained right atrial myocardial tissue (about 250 mg) at open-heart surgery from three groups of patients: no hemodynamic overload to the right atrium (control group; 12 ...
Tryptic peptides of Ca-ATPase in Et and E2 conformational states (Andersen, J. P., Jørgensen, P. L.,J. Membrane Biol. 88:187-198 (1985)) have been isolated by size exclusion high performance liquid chromatography in sodium dodecyl sulfate. This permitted unambiguous localization of a conformational sensitive tryptic split at Arg 198 by N-terminal amino acid sequence analysis. Other splits at Arg 505 and at Arg 819-Lys 825 were insensitive to E1-E2 transitions. Tryptic cleavage of Ca-ATPase after phosphorylation by inorganic phosphate showed that this enzyme form has a conformation similar to that of the vanadate-bound E2 state, both in membranous and in soluble monomeric Ca-ATPase. Hydrophobic labeling of Ca-ATPase in sarcoplasmic reticulum vesicles with the photoactivable reagent trifluoromethyl-[125I]iodophenyl-diazirine indicated that E2 and E2V states are more exposed to the membrane phase than E1 and E1P (Ca2+-occluded) states. The preferetial hydrophobic labeling in E2 forms was found to be
Introduction: Sarcoplasmic reticulum (SR) Ca2+ leak activates the inward Na+-Ca2+ exchange current (INCX) causing delayed afterdepolarsations (DADs) that promote arrhythmias. Whether this mechanism contributes to promotion of atrial fibrillation (AF) is unknown and was the object of this study.. Methods: Membrane currents and potentials (patch clamp) and [Ca2+]i (Fluo-3) were measured in right-atrial myocytes from sinus rhythm (Ctl) or chronic AF (cAF) patients. Tetracaine (1 mM) or single-channel recordings were used to quantify SR Ca2+ leak through ryanodine-receptor channels (RyR2). Proteins were measured by immunoblotting.. Results: Diastolic [Ca2+]i and SR Ca2+ content (integrated INCX during caffeine-induced [Ca2+]i transient [cCaT]) were unchanged, whereas diastolic SR Ca2+ leak was ∼50% higher in cAF than in Ctl (Figure). Calmodulin expression (+60%), CaMKII autophosphorylation (activation) at Thr287 (+40%) and Ser2808-phosphorylation (PKA/CaMKII-site) of RyR2 (+250%) were higher in ...
Buy, download and read The Development of the Sarcoplasmic Reticulum ebook online in PDF format for iPhone, iPad, Android, Computer and Mobile readers. Author: Anthony Martonosi. ISBN: 9781482283624. Publisher: CRC Press. Sarcoplasmic reticulum is a form of endoplasmic reticulum found in large quantities in mature muscle cells. Anthony Martonosi presents general information about the development and function of the sar
Xu, K.Y.; Vandegaer, K.; Becker, L.C., 1999: The sarcoplasmic reticulum Ca(2+)-ATPase is depressed in stunned myocardium after ischemia-reperfusion, but remains functionally coupled to sarcoplasmic reticulum-bound glycolytic enzymes
We have synthesized a new class of photoaffinity analogs, 2,3-O-(2,4,6-trinitrophenyl)-8-azido-ATP, -ADP and -AMP (TNP- 8N₃ATP, -ADP and -AMP), and their radiolabeled derivatives, and characterized their interaction with the sarcoplasmic reticulum Ca²⁺-ATPase. The TNP-8N₃-nucleotides were synthesized from ATP in three steps involving bromination in the 8-position of the adenine ring followed by displacement with an azido group and then trinitrophenylation of the resulting 8N₃-nucleotide with TNBS. Inclusion of the oxidizing agent, DTNB, in the final reaction was found to be necessary to prevent reduction of the azido group by the released sulfite anion and also elevated the yield of trinitrophenylation to about 80%. Purity was determined spectrophotometrically, as well as by anion exchange TLC and reversed phase HPLC. In the dark, the compounds were found to display most of the features of the parent TNP-nucleotides and interacted with the Ca²⁺-ATPase in a similar way. When ...
To make direct measurements of Ca2+ uptake and release by the sarcoplasmic reticulum (SR) of isolated smooth muscle cells, a fluorometric method for monitoring Ca2+ uptake by striated muscle SR vesicles (Kargacin, M.E., C.R. Scheid, and T.W. Honeyman. 1988. American Journal of Physiology. 245:C694-C698) was modified. With the method, it was possible to make continuous measurements of SR function in saponin-skinned smooth muscle cells in suspension. Calcium uptake by the SR was inhibited by thapsigargin and sequestered Ca2+ could be released by Br-A23187 and thapsigargin. From the rate of Ca2+ uptake by the skinned cells and the density of cells in suspension, it was possible to calculate the Ca2+ uptake rate for the SR of a single cell. Our results indicate that the SR Ca2+ pump in smooth muscle cells can remove Ca2+ at a rate that is 45-75% of the rate at which Ca2+ is removed from the cytoplasm of intact cells during transient Ca2+ signals. From estimates of SR volume reported by others and ...
Wyckelsma VL, MJ McKenna, FR Serpiello, CR Lamboley, RJ Aughey, NK Stepto, DJ Bishop and RM Murphy. Single fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+,K+-ATPase α and β isoforms in human skeletal muscle. Journal of Applied Physiology 118(6):699-706, 2015.. Perry BD, Levinger P, Morris HG, Petersen AC, Garnham AP, Levinger I and MJ McKenna. The effects of knee injury on skeletal muscle function, Na+,K+-ATPase content and isoform abundance. Physiological Reports 12;3(2). pii: e12294, 2015.. Lamboley CR, VL Wyckelsma, TL Dutka, MJ McKenna, RM Murphy and GD Lamb. Contractile properties and sarcoplasmic reticulum calcium content in type I and type II skeletal muscle fibres in active aged humans. Journal of Physiology. 593(1):2499-514, 2015.. Lamboley CR, RM Murphy, MJ McKenna and GD Lamb Sarcoplasmic reticulum Ca2+ uptake and leak properties and SERCA protein expression in type I and type II fibres of human skeletal muscle. Journal of Physiology ...
Several recent studies indicate that supplementation of the diet with inorganic nitrate results in a significant reduction in pulmonary O 2 uptake during sub-maximal exercise, an effect that appears to be related to enhanced skeletal muscle efficiency. The physiological mechanisms responsible for this effect are not completely understood but are presumably linked to the bioconversion of ingested nitrate into nitrite and thence to nitric oxide. Nitrite and/or nitric oxide may influence muscle contractile efficiency perhaps via effects on sarcoplasmic reticulum calcium handling or actin-myosin interaction, and may also improve the efficiency of mitochondrial oxidative phosphorylation. A reduced O 2 cost of exercise can be observed within 3 h of the consumption of 5-6 mmol of nitrate, and this effect can be preserved for at least 15 days provided that the same dose of nitrate is consumed daily. A reduced O 2 cost of exercise following nitrate supplementation has now been reported for several ...
The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. The Ca2+-dependent phosphorylation at 0 degree C (mean +/- S.E.) was 40.0 +/- 2.5 (n = 6) and 6.2 +/- 0.7 (n = 4) nmol/g wet wt. in rat extensor digitorum longus (EDL) and soleus muscle, respectively (P less than 0.001). The Ca2+-dependent 3-O-MFPase activity at 37 degrees C was 1424 +/- 238 (n = 6) and 335 +/- 56 (n = 4) nmol/min per g wet wt. in rat EDL and soleus muscle, respectively (P less than 0.01). The molecular activity calculated from these measurements amounted to 35 +/- 5 min-1 (n = 6) and 55 +/- 10 min-1 (n = 4) for EDL and soleus muscle respectively. These values were not different from the molecular activity calculated for purified Ca2+-ATPase (36 min-1). The ...
Variations of free calcium concentration ([Ca2+]) are powerful intracellular signals, controlling contraction as well as metabolism in muscle cells. To fully understand the role of calcium redistribution upon excitation and contraction in skeletal muscle cells, the local [Ca2+] in different compartments needs to be taken into consideration. Fluorescent probes allow the determination of [Ca2+] in the cytosol where myofibrils are embedded, the lumen of the sarcoplasmic reticulum (SR) and the mitochondrial matrix. Previously, models have been developed describing intracellular calcium handling in skeletal and cardiac muscle cells. However, a comprehensive model describing the kinetics of the changes in free calcium concentration in these three compartments is lacking. We designed a new 3D compartmental model of the half sarcomere with radial symmetry, which accounts for diffusion of Ca2+ into the three compartments and simulates its dynamics at rest and at various rates of stimulation in mice ...
Background: We and others have reported that myocardial protein phosphatase 1(PP1) activity in the end-stage heart failure (HF) is abnormally increased and contributes to the depressed cardiac function. In this regard, in vivo myocardial PP1 inhibition via endogenous cytosolic inhibitors such as inhibitor-2 (INH-2) has prevented HF progression by augmenting phospholamban (PLN) phosphorylation and thereby increasing cardiac function in the genetic cardiomyopathy model. However, it remained uncertain how INH-2, a cytosolic protein, exerts PP1 inhibition in the sarcoplasmic reticulum (SR). To this end, we investigated the molecular mechanism by which INH-2 inhibits PP1 and regulates contractility in cardiomyocytes.. Methods and Results: Cardiomyocytes were enzymatically isolated from six week-old male Wistar rats (n=10) and subjected to either adenoviral INH-2 infection or chemical PP1 inhibition by an application of 0.01-1microM of tautomycin (TM) and tautomycetin (TMC), followed by assessment of ...
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Cardiac ryanodine receptors (RyR2s) are Ca2+ release channels clustering in the sarcoplasmic reticulum membrane. These clusters are believed to be the elementary units of Ca2+ release. The distribution of these Ca2+ release units plays a critical role in determining the spatio-temporal profile and stability of sarcoplasmic reticulum Ca2+ release. RyR2 clusters located in the interior of cardiomyocytes are arranged in highly ordered arrays. However, little is known about the distribution and function of RyR2 clusters in the periphery of cardiomyocytes. Here, we used a knock-in mouse model expressing a green fluorescence protein (GFP)-tagged RyR2 to localize RyR2 clusters in live ventricular myocytes by virtue of their GFP fluorescence. Confocal imaging and total internal reflection fluorescence microscopy was employed to determine and compare the distribution of GFP-RyR2 in the interior and periphery of isolated live ventricular myocytes and in intact hearts. We found tightly ordered arrays of ...
FRAP experiments revealed that the dynamics of GFP-SERCA2a, either when diffused throughout the SR or when localized near the Z disk, did not show any difference in the mobile fraction and the diffusion constant (Mf of 88.8% ± 9.1%, n = 16, and 93.2% ± 4.0%, n = 23; D of 0.22 ± 0.1 μm2/s and 0.20 ± 0.1 μm2/s, respectively), as shown in Fig. 2C. The diffusion constant of GFP-InsP3R1 was similar in undifferentiated and differentiated myotubes (D of 0.13 ± 0.07 μm2/s and 0.07 ± 0.05 μm2/s, respectively). However, the Mf of GFP-InsP3R1 was reduced from 79.1% ± 11.2% (n = 20) to 62.8% ± 11.3% (P ≤ 0.01, n = 14) when the protein was organized at the Z disk level (Fig. 2F). InsP3R1 has been described to associate with the actin cytoskeleton through its interaction with protein 4.1N (26, 27). Accordingly, a GFP-InsP3R1 construct missing the C-terminal 14 aa that are responsible for binding to protein 4.1N (28) was prepared (GFP-InsP3R1Δ14). In differentiated myotubes, the GFP-InsP3R1Δ14 ...
With each heartbeat, a small amount of calcium entering the cell through membrane channels triggers the release of a larger amount of calcium from intracellular...
In both cardiac and slow-twitch skeletal muscle sarcoplasmic reticulum (SR) there are several systems involved in the regulation of Ca2+-ATPase function. T
As shown in Fig. 4 C (bottom), the application of isoproterenol also led to a larger fiber deflection, which is indicative of the expected force potentiation. This increase in single-twitch amplitude was paralleled by four interesting phenomena. First, the basal-normalized YFP/CFP ratio increased from 1.00 ± 0.02% to 1.06 ± 0.01% (mean ± SEM; n = 3 fibers) after injection of isoproterenol (Fig. 4 C, top). According to the calibration procedure described in the supplemental material, this would account for a rise in [Ca2+]SR from ∼278 to ∼311 μM. Second, the decrease of YFP/CFP ratio during single twitches was enhanced in the presence of isoproterenol without interim stimulation (Fig. 4 C, top), accounting for drops in [Ca2+]SR of ∼65 and ∼99 μM in the absence and presence of isoproterenol, respectively; this effect was even stronger upon 50 Hz stimulation, where the corresponding changes were calculated to be ∼83 and ∼153 μM. Third, the kinetics of the Ca2+-release/reuptake ...
It is the conformational change in these charged helices which is primarily responsible for the channel adopting an open configuration. When open, each Na + channel remains open for about lmsec, during which time approximately 6000 ions pass through its pore, presumably without any traffic congestion! 20 Cell Membrane Transport 2 3 4 5 Cytoplasmic domains Fig. 4. Schematic representation of the topography of the subunit of the Na + channel. Each channel consists of four repeats of this complex. This particular ATPase is slightly smaller than its plasmalemmal counterpart, containing only 1001 amino acids. This difference is due to the absence of a calmodulin regulatory site from the Ca2 + ATPase of the sarcoplasmic reticulum and its presence in the sarcolemmal Ca2 + ATPase. Instead of being regulated by calmodulin the Ca 2 + ATPase of the sarcoplasmic reticulum in cardiac and smooth muscle cells is regulated by another phosphorylatable protein - phospholamban. This is a pentamer, each subunit ...
The researchers put resistance-trained men on a six-week very-high-volume lifting program and then performed biopsies on the subjects vastus lateralis. The results showed a substantial increase in muscle fiber size (greater than 20 percent) that was accompanied by a roughly 30 percent reduction in the proportion of myofibrillar proteins. Those findings suggest that the hypertrophy was due to an increase in sarcoplasmic components (likely a combination of fluid and proteins related to metabolic stress).. Whats really interesting is that follow-up work from the same lab found that a heavier-load, lower-volume protocol resulted in type 2 fiber hypertrophy, but the changes occurred without significant increases in sarcoplasmic proteins and fluid.[5] Collectively, these studies suggest that bodybuilding-type training routines, with higher volume and moderate loads, produce greater increases in sarcoplasmic growth, whereas powerlifting-type programs, with lower volume and heavier loads, may generate ...
The researchers put resistance-trained men on a six-week very-high-volume lifting program and then performed biopsies on the subjects vastus lateralis. The results showed a substantial increase in muscle fiber size (greater than 20 percent) that was accompanied by a roughly 30 percent reduction in the proportion of myofibrillar proteins. Those findings suggest that the hypertrophy was due to an increase in sarcoplasmic components (likely a combination of fluid and proteins related to metabolic stress).. Whats really interesting is that follow-up work from the same lab found that a heavier-load, lower-volume protocol resulted in type 2 fiber hypertrophy, but the changes occurred without significant increases in sarcoplasmic proteins and fluid.[5] Collectively, these studies suggest that bodybuilding-type training routines, with higher volume and moderate loads, produce greater increases in sarcoplasmic growth, whereas powerlifting-type programs, with lower volume and heavier loads, may generate ...
treated with Ang II (10-6 mol/L) and subsequently harvested after 0, 2, 6, and 24 hours using a Nonide P40-based lysis buffer (BioChain Institute, Inc., Hayward, CA, USA) (13 ml HEPES pH 7.9, MgCl2, KCl, EDTA, sucrose, glycerol, sodium deoxycholate, Nonide P40 ...
Activation of a calmodulin (CaM)-dependent protein kinase associated with rabbit skeletal-muscle sarcoplasmic reticulum (SR) results in the phosphorylation of polypeptides of 450, 360, 165, 105, 89, 60, 34 and 20 kDa. Radioligand-binding studies indicated that a membrane-bound 60 kDa polypeptide contained both CaM- and ATP-binding domains. Under renaturing conditions on nitrocellulose blots, the 60 kDa polypeptide of the membrane exhibited CaM-dependent autophosphorylation activity, suggesting that it was the CaM-dependent protein kinase of SR. Ca2+/CaM-independent autophosphorylation of polypeptides of 62 and 45 kDa was found to occur in the light SR, whereas the Ca2+/CaM-dependent autophosphorylation activity was enriched in the heavy SR. Both these kinase activities were absent from transverse tubules, although these membranes were enriched in CaM-binding polypeptides of 160, 100 and 80 kDa. In the absence of Ca2+, CaM bound to a 33 kDa polypeptide of the membrane. The purified ryanodine ...
A compelling mystery in the study of exercise is mechanisms of skeletal muscle fatigue. Broadly described, muscle fatigue is the uncomfortable sensation that particular muscle groups are shutting down and muscle force production cannot continue. More specifically, muscle fatigue is defined as an activity-induced inability to continue to produce a desired level of force. Several groups suggest that a major cause of force loss during fatigue is reductions in the rates of sarcoplasmic reticulum (SR) calcium (Ca2+) release and uptake. These changes result in diminished contractile machinery activation, reduced force production and slowed relaxation. During exercise, adenosine 5-triphosphate (ATP) is the energy currency that is used to support force production. As a result of ATP hydrolysis and re-synthesis, adenosine diphosphate (ADP) and adenosine monophosphate (AMP) levels rise. AMP kinase (AMPK) is an enzyme that becomes activated as a result of increased AMP levels. It is thought to function as ...
TY - JOUR. T1 - Casq2 deletion causes sarcoplasmic reticulum volume increase, premature Ca2+ release, and catecholaminergic polymorphic ventricular tachycardia. AU - Knollmann, Björn C.. AU - Chopra, Nagesh. AU - Hlaing, Thinn. AU - Akin, Brandy. AU - Yang, Tao. AU - Ettensohn, Kristen. AU - Knollmann, Barbara E.C.. AU - Horton, Kenneth D.. AU - Weissman, Neil J.. AU - Holinstat, Izabela. AU - Zhang, Wei. AU - Roden, Dan M.. AU - Jones, Larry R.. AU - Franzini-Armstrong, Clara. AU - Pfeifer, Karl. PY - 2006/9/1. Y1 - 2006/9/1. N2 - Cardiac calsequestrin (Casq2) is thought to be the key sarcoplasmic reticulum (SR) Ca2+ storage protein essential for SR Ca2+ release in mammalian heart. Human CASQ2 mutations are associated with catecholaminergic ventricular tachycardia. However, homozygous mutation carriers presumably lacking functional Casq2 display surprisingly normal cardiac contractility. Here we show that Casq2-null mice are viable and display normal SR Ca2+ release and contractile function ...
Ion pumps are integral membrane proteins responsible for transporting ions against concentration gradients across biological membranes. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), a member of the P-type ATPases family, transports two calcium ions per hydrolyzed ATP molecule via an alternating-access mechanism. High-resolution crystallographic structures provide invaluable insight on the structural mechanism of the ion pumping process. However, to understand the molecular details of how ATP hydrolysis is coupled to calcium transport, it is necessary to gain knowledge about the conformational transition pathways connecting the crystallographically resolved conformations. Large-scale transitions in SERCA occur at time-scales beyond the current reach of unbiased molecular dynamics simulations. Here, we overcome this challenge by employing the string method, which represents a transition pathway as a chainofstates linking two conformational endpoints. Using a multiscale methodology, we have ...
In muscle cells, the excitation-contraction cycle is triggered by an increase in the concentration of free cytoplasmic Ca(2+). The Ca(2+)-ATPase present in the membrane of the sarcoplasmic reticulum (SR) pumps Ca(2+) from the cytosol into this intracellular compartment, thus promoting muscle relaxation. The microsomal fraction derived from the longitudinal smooth muscle of the body wall from the sea cucumber Ludwigothurea grisea retains a membrane-bound Ca(2+)-ATPase that is able to transport Ca(2+) mediated by ATP hydrolysis. Immunological analyses reveal that monoclonal antibodies against sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA1 and SERCA2a) cross-react with a 110 kDa band, indicating that the sea cucumber Ca(2+)-ATPase is a SERCA-type ATPase. Like the mammalian Ca(2+)-ATPase isoforms so far described, the enzyme also shows a high affinity for Ca(2+) and ATP, has an optimum pH of approximately 7.0 and is sensitive to thapsigargin and cyclopiazonic acid, specific inhibitors of the ...
The calcium release channel (CRC) from skeletal muscle is an unusually large tetrameric ion channel of the sarcoplasmic reticulum, and it is a major component of the triad junction, the site of excitation contraction coupling. The three-dimensional architecture of the CRC was determined from a random conical tilt series of images extracted from electron micrographs of isolated detergent-solubilized channels prepared in a frozen-hydrated state. Three major classes of fourfold symmetric images were identified, and three-dimensional reconstructions were determined for two of these. The two independent reconstructions were almost identical, being related to each other by a 180 degrees rotation about an axis in the plane of the specimen grid. The CRC consists of a large cytoplasmic assembly (29 x 29 x 12 nm) and a smaller transmembrane assembly that protrudes 7 nm from one of its faces. A cylindrical low-density region, 2-3 nm in apparent diameter, extends down the center of the transmembrane ...
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) family of proteins function as calcium pumps in the endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) membranes. SERCA1a is found exclusively in fast-twitch muscle cells and mediates muscle relaxation by pumping calcium back into the SR after calcium has been released into the cytoplasm to elicit muscle contraction. The mechanism which allows SR biogenesis is not known, but SR membrane is believed to bud from the ER. One hypothesis is that SERCA1a proteins play a significant role in SR biogenesis in fast-twitch skeletal muscle due the proteins large size and clustering into large arrays in the SR membrane. SERCA1a arrays could recruit lipids which would allow for a large increase in membrane size that could result in the formation of the SR. Also, SERCA1a is highly expressed during the early stages of myogenesis, at the same time the first emergence of the SR is observed. It is known that SERCA1a contains ER targeting information ...
Triadin, also known as TRDN, is a human gene associated with the release of Calcium ions from the sarcoplasmic reticulum triggering muscular contraction through calcium-induced calcium release. Triadin is a multiprotein family, arising from different processing of the TRDN gene on chromosome 6. It is a transmembrane protein on the sarcoplasmic reticulum due to a well defined hydrophobic section and it forms a quaternary complex with the cardiac Ryanodine receptor (RYR2), calsequestrin (CASQ2) and junctin proteins. The luminal (inner compartment of the sarcoplasmic reticulum) section of Triadin has areas of highly charged amino acid residues that act as luminal Ca2+ receptors. Triadin is also able to sense luminal Ca2+ concentrations by mediating interactions between RYR2 and CASQ2. Triadin has several different forms; Trisk 95 and Trisk 51, which are expressed in skeletal muscle, and Trisk 32 (CT1), which is mainly expressed in cardiac muscle. TRDN has been shown to interact with RYR1. Triadin ...
TY - JOUR. T1 - The role of sarcolipin and ATP in the transport of phosphate ion into the sarcoplasmic reticulum. AU - Becucci, Lucia. AU - Guidelli, Rolando. AU - Karim, Christine B.. AU - Thomas, David D.. AU - Veglia, Gianluigi. N1 - Funding Information: This work was supported by grants from Ente Cassa di Risparmio di Firenze (R.G.), the Italian Ministero dellIstruzione, dellUniversità e della Ricerca (R.G.), and the National Institutes of Health (grants GM64742, HL80081, and GM072701 to G.V). PY - 2009/11/15. Y1 - 2009/11/15. N2 - In a previous study, sarcolipin (SLN) was shown to form channels selective toward chloride ion when incorporated in a mercury-supported tethered bilayer lipid membrane (tBLM). Its incorporation had only a modest permeabilizing effect on phosphate ion. In this note the resistance of a tBLM membrane incorporating sarcolipin was investigated by electrochemical impedance spectroscopy in aqueous solutions of 0.05 M sodium phosphate of pH ranging from 5.3 to 8, in ...
TY - JOUR. T1 - Transmembrane Ca2+ gradient-mediated change of fluidity in the inner layer of phospholipids modulates Ca2+-ATPase of sarcoplasmic reticulum. AU - Tu, Yaping. AU - Xu, H.. AU - Yang, F. Y.. PY - 1994. Y1 - 1994. N2 - Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without transmembrane Ca2+ gradient have been prepared. Different fluorescence probes (DPH, TMA-DPH and n-AS), were used to determine the effect of transmembrane Ca2+ gradient on the lipid fluidity both in outer and inner layer of Ca2+-ATPase-containing SR vesicles. The results showed that transmembrane Ca2+ gradient could significantly decrease the fluidity of the inner layer of SR membrane, while no obvious change was monitored in the outer layer. This may be deduced that Ca2+-ATPase might be modulated mainly by the transmembrane Ca2+ gradient-mediated alteration of physical state of phospholipid in the inner layer of SR membrane.. AB - Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without ...
The precise control of Ca2+ levels during the contraction-relaxation cycle in cardiac myocytes is extremely important for normal beat-to-beat contractile activity. The sarcoplasmic reticulum (SR) plays a key role controlling calcium concentration in the cytosol. The SR Ca2+-ATPase (SERCA2) transports Ca2+ inside the SR lumen during relaxation of the cardiac myocyte. Calsequestrin (Casq2) is the main protein in the SR lumen, functioning as a Ca2+ buffer and participating in Ca2+ release by interacting with the ryanodine receptor 2 (RyR2) Ca2+-release channel. Alterations in normal Ca2+ handling significantly contribute to the contractile dysfunction observed in cardiac hypertrophy and in heart failure. Transcriptional regulation of the SERCA2 gene has been extensively studied and some of the mechanisms regulating its expression have been elucidated. Overexpression of Sp1 factor in cardiac hypertrophy downregulates SERCA2 gene expression and increased levels of thyroid hormone up-regulates its ...
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TY - JOUR. T1 - Synergistic dual automaticity in sinoatrial node cell and tissue models. AU - Zhang, Hong. AU - Joung, Boyoung. AU - Shinohara, Tetsuji. AU - Mei, Xi. AU - Chen, Peng-Sheng. AU - Lin, Shien-Fong. PY - 2010. Y1 - 2010. N2 - Background: The mechanism of sinoatrial node (SAN) automaticity is traditionally attributed to membrane ion currents. Recent evidence indicates spontaneous sarcoplasmic reticulum (SR) Ca2+ cycling also plays an important role. Methods and Results: A computer simulation on SAN cell and 1D tissue model was performed. In the SAN cells, SR Ca2+ cycling broadly modulated the sinus rate from 1.74 Hz to 3.87 Hz. Shortening of the junctional SR refilling time and increase of SR Ca2+ release were responsible for sinus rate acceleration. However, under the fast SR Ca2+ cycling, decreased L-type Ca2+ current (ICaL) resulted in irregular firing. When Ca2+ cycling was suppressed, If and ICaT both acted to stabilize the pacemaker rhythm, but ICaT had less effect than If. At ...
Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Here, we...
Contraction of the heart is a complex process initiated by the electrical excitation of cardiac myocytes (excitation-contraction coupling, ECC). In cardiac myocytes, Ca2+ influx induced by activation of voltage-dependent L-type Ca channels (DHP receptors) upon membrane depolarization triggers the release of Ca2+ via Ca2+ release channels (ryanodine receptors) of sarcoplasmic reticulum (SR) through a Ca2+ -induced Ca release (CICR) mechanism. Ca2+ ions released via the CICR mechanism diffuse through the cytosolic space to contractile proteins to bind to troponinC resulting in the release of inhibition induced by troponinI. The Ca2+ binding to troponinC thereby triggers the sliding of thin and thick filaments, that is, the activation of a crossbridge and subsequent cardiac force development and/or cell shortening. Recovery occurs as Ca2+ is pumped out of the cell by the Na+/Ca2+ exchanger (NCX) or is returned to the sarcoplasmic reticulum (SR) by sarco(endo)plasmic Ca2+ -ATPase (SERCA) pumps on ...
Backgrounds Previous studies showed that overexpression of sarco-endoplasmic reticulum calcium ATPase (SERCA2a) in a variety of heart failure (HF) models was associated with greatly enhanced cardiac performance. However, it still undefined the effect of SERCA2a overexpression on the systemic inflammatory response and neuro-hormonal factors. Methods A rapid right ventricular pacing model of experimental HF was used in beagles. Then the animals underwent recombinant adeno-associated virus 1 (rAAV1) mediated gene trans¬fection by direct intra-myocardium injection. HF animals were randomized to receive the SERCA2a gene, enhanced green fluorescent protein (control) gene, or equivalent phosphate buffered saline. Thirty days after gene delivery, the cardiac function was evaluated by echocardiographic testing. The protein level of SERCA2a was measured by western blotting. The proteomic analysis of left ventricular (LV) sample was determined using two-dimensional (2-D) gel electrophoresis and MALDI-TOF-MS. The
Areas of active investigation include: use of laser-scanning confocal microscopy to measure calcium sparks, which are brief localized increases in fluorescence from a Ca-indicator such as fluo-3 that are thought to be reflective of the transient opening of one or a few RyRs (=ryanodine receptors), the Ca release channels of the sarcoplasmic reticulum (SR); the possibility that the mechanism of activation of RyRs involves both voltage-gating and Ca-gating; the nature of the mechanism whereby SR Ca release is inactivated by a rise in myoplasmic free [Ca]; the possibility that either activation or inactivation of SR Ca release may vary with the RyR isoform composition (RyR1, RyR3, etc.); estimation of local Ca movements within the sarcomere by means of computer modeling, including estimation of the kinetics of binding of Ca to the intracellular Ca buffers troponin, parvalbumin, ATP, and the SR Ca pump ...
Catalyzes the formation of the signaling molecule cAMP downstream of G protein-coupled receptors (PubMed:17916776, PubMed:17110384). Functions in signaling cascades downstream of beta-adrenergic receptors in the heart and in vascular smooth muscle cells (PubMed:17916776). Functions in signaling cascades downstream of the vasopressin receptor in the kidney and has a role in renal water reabsorption. Functions in signaling cascades downstream of PTH1R and plays a role in regulating renal phosphate excretion. Functions in signaling cascades downstream of the VIP and SCT receptors in pancreas and contributes to the regulation of pancreatic amylase and fluid secretion (By similarity). Signaling mediates cAMP-dependent activation of protein kinase PKA. This promotes increased phosphorylation of various proteins, including AKT. Plays a role in regulating cardiac sarcoplasmic reticulum Ca(2+) uptake and storage, and is required for normal heart ventricular contractibility. May contribute to normal heart ...
These results show that vasostatin, an NH2-terminal fragment of human calreticulin, can inhibit endothelial cell proliferation in vitro, suppress neovascularization in vivo, and prevent or reduce growth of experimental tumors. Calreticulin, a ubiquitous and highly conserved protein originally identified in skeletal muscle sarcoplasmic reticulum, serves as one of the major storage depots for calcium ions within the endoplasmic reticulum and participates in calcium signaling ((34)-(36)). The NH2-domain of calreticulin, which includes aa 1-180, is the most conserved domain among the calreticulins so far cloned and has no homology to other protein sequences ((34), (35)). Although it does not bind calcium, it can bind the cytoplasmic domain of α subunits of integrins regulating cell attachment ((37)), can interact with the nuclear receptors for glucocorticoid, androgen, and retinoic acid, regulating their binding to DNA ((38)), and can, once phosphorylated, bind stem-loop structures at the 3′-end ...
Muscle Contraction When a action potential arrives via a motor neurone to the muscle - it depolarizes the transverse tubules, which triggers calcium to be released from the sarcoplasmic reticulum by the opening of calcium channels in the sarcoplasmic reticulum membrane.. The calcium ions bind with the troponin molecules on the actin filaments - causing them to change shape, this causes the tropomyosin to move, exposing a site that the myosin can bind to.. The myosin then quickly tilts through 45 degrees - so the actin gets pulled towards the centre of the sacromere. As teh head tilts the ADP and Pi are released, and an ATP molecule takes their place.. The myosin head then hydrolyses the ATP to ADP and Pi - the energy generated from this is used to detach the myosin head from the actin filament. The cycle then starts all over again!. ...
The mutation underlying myotonic dystrophy is the expansion of polymorphic CTG repeat in the 3-noncoding region of the myotonin protein kinase (MtPK) gene mapping to chromosome 19q13.3. A full-length cDNA of human MtPK was cloned and expressed in COS-1 cells. We purified native full-length MtPK from rat skeletal muscle. This 70 kDa MtPK is localized in sarcoplasmic reticulum fraction, whereas the previously reported 55 kDa protein was observed in nuclear extract or the sarcoplasmic reticulum membrane. Based on the cDNA sequence, human MtPK was previously reported to have two amino acid sequence variations at the C-terminus, one GAARAP (RAP type) and PALPEP (PEP type). The MtPK purified appeared to be almost entirely RAP type. Stable expression of MtPK in mouse C2C12 cells caused the activation of chloride efflux. Expansion of CTG repeats suppressed myogenic differentiation. Collectively, the results indicate that prolonged MtPK activation provides a link between intracellular signal transduction
Calcium pumps transport calcium back into sarcoplasmic reticulum, ending an action potential and causing relaxation. The process of muscle contraction will continue until the action potential is terminated. Relaxation is achieved when calcium pumps have actively transported calcium back into the sarcoplasmic reticulum, reversing the changes that previously occurred in troponin. Tropomyosin is now back in its original position covering the myosin binding sites on actin, preventing crossbridges and power stroke cycling. - Stock Video Clip K005/0663
The endoplasmic reticulum is a major organelle in all eukaryotic cells which performs multiple functions including protein and lipid synthesis and sorting, drug metabolism, and Ca 2+ storage and release. The endoplasmic reticulum, and its specialized muscle counterpart the sarcoplasmic reticulum, is the largest and most extensive of Ca 2+ storage organelle in eukaryotic cells, often occupying in excess of 10% of the cell volume. There are three major components of Ca 2+ storage organelles which mediate their major functions: Ca 2+ uptake, mediated by pumps and exchangers; storage enhanced by luminal Ca 2+ binding proteins, and Ca 2+ mobilization mediated by specific ion channels. Ca 2+ mobilization from the endoplasmic reticulum plays a central role in Ca 2+ signaling. Through Ca 2+ release channels in its membrane, the pervading and plastic structure of the endoplasmic reticulum allows Ca 2+ release to be rapidly targeted to specific cytoplasmic sites across the whole cell. That several
Author: P. SATHYAVATHI. Category: Physiology. [Download PDF]. Abstract:. Background and objectives: Calcium is the prime mediator of the contractile mechanism in frog ventricle. Sarcoplasmic reticulum (SR) releases calcium by a well-known calcium induced calcium release (CICR) mechanism. CICR is mediated by ryanodine receptor (RyR) and inositol 1,4, 5- triphosphate (IP3) receptors on the SR membrane. This increase in cytosolic calcium concentration causes contraction of the cardiac muscle. Aim :The study aims at examining the interdependent role of the known calcium release channels on the SR in frog ventricle. Materials and Methods and the Study Design: Isolated ventricular strips of frogs (rana hexadactyla) were used for the study. The study design includes subjecting the ventricular strip to continuous electrical stimulation with imposed rest periods intermittently to examine the diastolic depletion of calcium from the SR. The magnitude of decay of the post rest amplitude in relation to the ...
Calsequestrin is the principal calcium-binding protein present in the sarcoplasmic reticulum of cardiac and skeletal muscle [(PUBMED:3379055)]. It is a highly acidic protein that is able to bind over 40 calcium ions and acts as an internal calcium store in muscle. Sequence analysis has suggested that calcium is not bound in distinct pockets via EF-hand motifs, but rather via presentation of a charged protein surface. Two forms of calsequestrin have been identified. The cardiac form is present in cardiac and slow skeletal muscle and the fast skeletal form is found in fast skeletal muscle. The release of calsequestrin-bound calcium (through a a calcium release channel) triggers muscle contraction. The active protein is not highly structured, more than 50% of it adopting a random coil conformation [(PUBMED:3427023)]. When calcium binds there is a structural change whereby the alpha-helical content of the protein increases from 3 to 11% [(PUBMED:3427023)]. Both forms of calsequestrin are ...
Reversibly inhibits the activity of ATP2A2 in cardiac sarcoplasmic reticulum by decreasing the apparent affinity of the ATPase for Ca(2+). Modulates the contractility of the heart muscle in response to physiological stimuli via its effects on ATP2A2. Modulates calcium re-uptake during muscle relaxation and plays an important role in calcium homeostasis in the heart muscle. The degree of ATP2A2 inhibition depends on the oligomeric state of PLN. ATP2A2 inhibition is alleviated by PLN phosphorylation (By similarity).
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It is known that sarcoplasmic reticulum (SR) Ca2+ release in cardiac muscle is initiated via cardiac ryanodine receptor (RyR2) through a mechanism called Ca2+-induced Ca2+ release. However, how the SR Ca2+ release is terminated is undetermined. The objective of the current study is to understand the molecular basis and regulation of RyR2-mediated Ca2+ release termination and its role in the pathogenesis of cardiac diseases. Based on recent 3D structural analyses, the NH2-terminal region of RyR2 interacts with the channel domain via the central domain and undergoes dynamic conformational changes during channel gating. It has also been discovered that the NH2-terminal region consists of three distinct domains. HEK293 cell studies on domain deletions and disease mutations demonstrate that the different domains play different roles in RyR2 function. The NH2-terminal region is a major determinant of Ca2+ release activation and termination. Enhanced luminal Ca2+ activation of RyR2 has been linked to ...
mouse Asph protein: 26-kDa protein isolated from cardiac junctional sarcoplasmic reticulum; hydroxylates ASP or ASN residues in EGF domains of some proteins; RefSeq NM_023066
In human disease and experimental animal models, depressed Ca2+ handling in failing cardiomyocytes is widely attributed to impaired sarcoplasmic reticulum (SR) function. In mice, disruption of the PLN gene encoding phospholamban (PLN) or expression of dominant-negative PLN mutants enhances SR and cardiac function, but effects of PLN mutations in humans are unknown. Here, a T116G point mutation, substituting a termination codon for Leu-39 (L39stop), was identified in two families with hereditary heart failure. The heterozygous individuals exhibited hypertrophy without diminished contractile performance. Strikingly, both individuals homozygous for L39stop developed dilated cardiomyopathy and heart failure, requiring cardiac transplantation at ages 16 and 27. An over 50% reduction in PLN mRNA and no detectable PLN protein were noted in one explanted heart. The expression of recombinant PLN-L39stop in human embryonic kidney (HEK) 293 cells and adult rat cardiomyocytes showed no PLN inhibition of SR ...
In human disease and experimental animal models, depressed Ca2+ handling in failing cardiomyocytes is widely attributed to impaired sarcoplasmic reticulum (SR) function. In mice, disruption of the PLN gene encoding phospholamban (PLN) or expression of dominant-negative PLN mutants enhances SR and cardiac function, but effects of PLN mutations in humans are unknown. Here, a T116G point mutation, substituting a termination codon for Leu-39 (L39stop), was identified in two families with hereditary heart failure. The heterozygous individuals exhibited hypertrophy without diminished contractile performance. Strikingly, both individuals homozygous for L39stop developed dilated cardiomyopathy and heart failure, requiring cardiac transplantation at ages 16 and 27. An over 50% reduction in PLN mRNA and no detectable PLN protein were noted in one explanted heart. The expression of recombinant PLN-L39stop in human embryonic kidney (HEK) 293 cells and adult rat cardiomyocytes showed no PLN inhibition of SR ...
ABSTRACT: We construct a detailed mathematical model for Ca2+ regulation in the ventricular myocyte that includes novel descriptions of subcellular mechanisms based on recent experimental findings: 1) the Keizer-Levine model for the ryanodine receptor (RyR), which displays adaptation at elevated Ca2+; 2) a model for the L-type Ca2+ channel that inactivates by mode switching; and 3) a restricted subspace into which the RyRs and L-type Ca2+ channels empty and interact via Ca2+. We add membrane currents from the Luo-Rudy Phase II ventricular cell model to our description of Ca2+ handling to formulate a new model for ventricular action potentials and Ca2+ regulation. The model can simulate Ca2+ transients during an action potential similar to those seen experimentally. The subspace [Ca2+] rises more rapidly and reaches a higher level (10-30 microM) than the bulk myoplasmic Ca2+ (peak [Ca2+]i approximately 1 microM). Termination of sarcoplasmic reticulum (SR) Ca2+ release is predominately due to ...
So says Yasser A. Mahmmoud of the University of Aarhus in Denmark: In muscle cells the sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA) couples the free energy of ATP hydrolysis to pump Ca2+ ions from the cytoplasm to the SR lumen. In addition, SERCA plays a key role in non-shivering thermogenesis through uncoupled reactions, where ATP hydrolysis takes place without active Ca2+ […]
This gene encodes one of the SERCA Ca(2+)-ATPases, which are intracellular pumps located in the sarcoplasmic or endoplasmic reticula of muscle cells. This enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen, and is involved in calcium sequestration associated with muscular excitation and contraction. Alternative splicing results in multiple transcript variants encoding different isoforms.
The ERRα transcriptional pathway has been shown in recent years to play a central role in the regulation of mitochondrial energy metabolism in many cell and tissue types, including striated muscle (20, 63). In the present study, we explored the hypothesis that ERRα may function more broadly as an essential regulatory component of myogenesis. Myocyte differentiation requires precise regulation of multiple gene programs, consisting of genes encoding contractile and sarcoplasmic reticulum proteins, along with ubiquitously expressed proteins involved in energy metabolism. Such coordination may be mediated by transcriptional regulators of energy metabolism genes, including the ERR isoforms and their PGC-1 coactivators, that are temporally induced as part of the myogenic program (Refs. 28, 66; present study). Our findings suggest that ERRα does promote differentiation when overexpressed and is required for normal myogenesis. A surprising finding was that the broader regulatory function for ERRα in ...
A molecular ribbon model of a calcium pump, a structure responsible for coordinating muscular contraction or signalling other cells along the cell membrane. Calcium pumps are embedded in the sarcoplasmic reticulum of muscle cells, transferring two calcium ions for each molecule of ATP broken down. - Stock Image C017/6296
Phospholamban (PLN) is an integral membrane protein that regulates calcium homeostasis by inhibiting sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA) in cardiac muscle. PLN exists in two primary oligomeric forms: (1) a monomer that directly bind
... sarcoplasmic reticulum; Golgi apparatus; lysosome; mitochondrion (inner and outer membranes); nucleus (inner and outer ... In eucaryotic cells, new phospholipids are manufactured by enzymes bound to the part of the endoplasmic reticulum membrane that ... Distinct types of membranes also create intracellular organelles: endosome; smooth and rough endoplasmic reticulum; ...
Deamer, D.W.; Baskin, R.J. (1969). "Ultrastructure of sarcoplasmic reticulum preparations". Journal of Cell Biology. 42 (1): ... revealing for the first time particles related to functional ATPase enzymes within the membranes of sarcoplasmic reticulum. ...
The sarcoplasmic reticulum, a specialized type of smooth endoplasmic reticulum, forms a network around each myofibril of the ... When the action potential reaches the sarcoplasmic reticulum it triggers the release of Ca2+ from the Ca2+ channels. The Ca2+ ... The sarcoplasmic reticulum serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it ... Very quickly Ca2+ is actively transported back into the sarcoplasmic reticulum, which blocks the interaction between the thin ...
... endoplasmic reticulum or sarcoplasmic reticulum). Although CICR was first proposed for skeletal muscle in the 1970s, it is now ... Fabiato A (July 1983). "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum". The American Journal of ... Endo M (January 1977). "Calcium release from the sarcoplasmic reticulum". Physiological Reviews. 57 (1): 71-108. doi:10.1152/ ... relies on sarcolemma depolarization and subsequent Ca2+ entry to trigger Ca2+ release from the sarcoplasmic reticulum. When an ...
Opening of the sarcoplasmic reticulum's Ca2+ channels. Increase in cytosolic Ca2+ concentrations and the interaction of these ... Ca2+ capture by the sarcoplasmic reticulum, causing a new conformational change in tropomyosin that inhibits the actin-myosin ...
This is due to relatively spare sarcoplasmic reticulum. Because of requirements for high force production, myofiber and ... In addition to the reduction in sarcoplasmic reticulum, relatively large myofibril diameters lead to increased diffusion times ... In Cotinus mutabilis, asynchronous muscles are composed of 58.1% myofibril, 36.7% mitochondria, and 1.6% sarcoplasmic reticulum ... sarcoplasmic reticulum. Although synchronous muscle has a higher percentage of myofibril, the cross-sectional area of ...
Proteins of the cardiac junctional sarcoplasmic reticulum membrane". The Journal of Biological Chemistry. 272 (37): 23389-97. ... their functions which involve roles in the calcium storage and release process in the endoplasmic and sarcoplasmic reticulum as ... plasmic reticulum membrane". The Journal of Biological Chemistry. 275 (50): 39555-68. doi:10.1074/jbc.M005473200. PMID 11007777 ...
D. Chadwick (2002). Role of the sarcoplasmic reticulum in smooth muscle. John Wiley and Sons. pp. 259-264. ISBN 0-470-84479-5. ...
Chadwick, D. (2002). Role of the sarcoplasmic reticulum in smooth muscle. John Wiley and Sons. pp. 259-264. ISBN 978-0-470- ...
... concentration in the sarcoplasmic reticulum in cardiac cells maintenance of Ca2+ concentration in the endoplasmic reticulum of ... The sarcoplasmic reticulum release of Ca2+ is inhibited. Other Ca2+ influx channels are inhibited. If the action potential ... The exchanger is usually found in the plasma membranes and the mitochondria and endoplasmic reticulum of excitable cells. The ...
Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 is an enzyme that in humans is encoded by the ATP2A1 gene. This gene ... 2001). "Mutations of either or both Cys876 and Cys888 residues of sarcoplasmic reticulum Ca2+ATPase result in a complete loss ... Pieske B, Maier LS, Schmidt-Schweda S (2002). "Sarcoplasmic reticulum Ca2+ load in human heart failure". Basic Res. Cardiol. 97 ... 1996). "Mutations in the gene-encoding SERCA1, the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase, are ...
... , also known as TRDN, is a human gene associated with the release of calcium ions from the sarcoplasmic reticulum ... The luminal (inner compartment of the sarcoplasmic reticulum) section of Triadin has areas of highly charged amino acid ... Proteins of the cardiac junctional sarcoplasmic reticulum membrane". J. Biol. Chem. 272 (37): 23389-97. doi:10.1074/jbc.272.37. ... 2007). "Histidine-rich Ca-binding protein interacts with sarcoplasmic reticulum Ca-ATPase". Am. J. Physiol. Heart Circ. Physiol ...
Each muscle fiber contains sarcolemma, sarcoplasm, and sarcoplasmic reticulum. The functional unit of a muscle fiber is called ... Signals from motor neurons cause myofibers to depolarize and therefore release calcium ions from the sarcoplasmic reticulum. ... Striated muscle tissue contains T-tubules which enables the release of calcium ions from the sarcoplasmic reticulum. Skeletal ...
It resides in the sarcoplasmic reticulum (SR) within myocytes. It is a Ca2+ ATPase that transfers Ca2+ from the cytosol of the ... Sarcoplasmic+Reticulum+Calcium-Transporting+ATPases at the US National Library of Medicine Medical Subject Headings (MeSH). ... Its major function is to transport calcium from the cytosol into the sarcoplasmic reticulum. SERCA is a P-type ATPase. ... "Thermogenic activity of Ca2+-ATPase from skeletal muscle heavy sarcoplasmic reticulum: the role of ryanodine Ca2+ channel". ...
The calcium is then held within the sarcoplasmic reticulum by a protein called calsequestrin. Fine-tuning of this process can ... Sarcoplasmic reticulum calcium content increases in response to stimulation from catecholamines, explaining why arrhythmias in ... While calcium is generally released from the sarcoplasmic reticulum in response to an action potential, calcium sparks can also ... At the start of each heartbeat, calcium is released from the sarcoplasmic reticulum through specialised channels known as ...
The sarco/endoplasmic reticulum calcium-ATPase (SERCA) actively pumps Ca2+ back into the sarcoplasmic reticulum. As Ca2+ ... Note that the sarcoplasmic reticulum has a large calcium buffering capacity partially due to a calcium-binding protein called ... The active pumping of Ca2+ ions into the sarcoplasmic reticulum creates a deficiency in the fluid around the myofibrils. This ... Termination of crossbridge cycling can occur when Ca2+ is actively pumped back into the sarcoplasmic reticulum. When Ca2+ is no ...
Tada M, Kirchberger MA, Katz AM (1975). "Phosphorylation of a 22,000-dalton component of the cardiac sarcoplasmic reticulum by ... Takenaka H, Adler PN, Katz AM (1982). "Calcium fluxes across the membrane of sarcoplasmic reticulum vesicles". J Biol Chem. 257 ... Katz AM, Repke DI, Dunnett J, Hasselbach W (1977). "Dependence of calcium permeability of sarcoplasmic reticulum vesicles on ... "Reaction mechanism of Ca2+-dependent ATP hydrolysis by skeletal muscle sarcoplasmic reticulum in the absence of added alkali ...
A calcium spark is the microscopic release of calcium (Ca2+) from a store known as the sarcoplasmic reticulum (SR), located ... Fabiato, A (1983). "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum". Am. J. Physiol. 245: C1-C14. ... located on the sarcoplasmic reticulum and activation, by the action potential causes the DHPRs to change shape. In cardiac and ... see sarcoplasmic reticulum for more details). Similarly, a decrease in Ca2+ concentration within the SR has also proven to ...
... is a calcium-binding protein that acts as a calcium buffer within the sarcoplasmic reticulum. The protein helps ... It also helps the sarcoplasmic reticulum store an extraordinarily high amount of calcium ions. Each molecule of calsequestrin ... even though the concentration of calcium in the sarcoplasmic reticulum is much higher than in the cytosol. ... "Crystal structure of calsequestrin from rabbit skeletal muscle sarcoplasmic reticulum". Nat. Struct. Biol. 5 (6): 476-83. doi: ...
He is known for his discovery of the sarcoplasmic reticulum. He studied medicine at the Universities of Pavia and Bologna, ... In March 1902, he provided the first accurate description of the reticular network (sarcoplasmic reticulum) in skeletal muscle ... Vanio Vannini and Umberto Muscatello The sarcoplasmic reticulum: its discovery and rediscovery Nature Reviews Molecular Cell ... In 1961 "Veratti's reticulum" was re-discovered through the use of electron microscopy. Veratti E., 1902. Ricerche sulla fine ...
It is specifically localized to the sarcoplasmic reticulum and nuclear membrane, and is involved in anchoring PKA to the ... A protein that targets A-kinase to the sarcoplasmic reticulum". J Biol Chem. 270 (16): 9327-33. doi:10.1074/jbc.270.16.9327. ... nuclear membrane or sarcoplasmic reticulum. AKAP6 has been shown to interact with Ryanodine receptor 2 and PDE4D3. GRCh38: ...
Schulte, LM; Navarro, J; Kandarian, SC (May 1993). "Regulation of sarcoplasmic reticulum calcium pump gene expression by ... that the unloading state of spaceflight and of HS also increases the expression of fast type II sarcoplasmic reticulum (SR) ...
... that regulates several sarcoplasmic reticulum Ca2+-ATPases by reducing the accumulation of Ca2+ in the sarcoplasmic reticulum ... Sarcoplasmic reticulum Ca2+-ATPases are transmembrane proteins that catalyze the ATP-dependent transport of Ca2+ from the ... Sarcolipin is an important mediator of muscle based non shivering thermogenesis (NST). It causes the sarcoplasmic reticulum ... "Sarcolipin uncouples hydrolysis of ATP from accumulation of Ca2+ by the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum ...
This increases the re-uptake of calcium by the sarcoplasmic reticulum. β-blockers are sympatholytic drugs. Some β-blockers ... Protein kinase A also increases the release of calcium from the sarcoplasmic reticulum, which causes a positive inotropic ...
These calcium ions bind to and open more calcium channels (called ryanodine receptors) located on the sarcoplasmic reticulum ... Koivumäki, Jussi T.; Korhonen, Topi; Tavi, Pasi (2011-01-01). "Impact of Sarcoplasmic Reticulum Calcium Release on Calcium ... in a calcium store known as the sarcoplasmic reticulum (SR). Release of Ca2+ from the SR, via a process called calcium-induced ... calcium is released from the sarcoplasmic reticulum, within the cell. This calcium then increases activation of the sodium- ...
In the cell, they are located in the sarcoplasmic or endoplasmatic reticulum. SERCA1a is a type IIA pump. The second group of ... Toyoshima C, Nakasako M, Nomura H, Ogawa H (June 2000). "Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 ... One report suggests that this sarcoplasmic reticulum (SR) Ca2+ ATPase is homodimeric. Crystal structures have shown that the ... "The dimeric form of Ca2+-ATPase is involved in Ca2+ transport in the sarcoplasmic reticulum". The Biochemical Journal. 414 (3 ...
"Thyroxine induced transformation in sarcoplasmic reticulum of rabbit soleus and psoas muscles". Zeitschrift für Naturforschung ...
Calcium is released from its storage area in the cell's sarcoplasmic reticulum. An impulse from a nerve cell causes calcium ... Calcium is released from the sarcoplasmic reticulum into the sarcomere when a muscle is stimulated to contract. This calcium ... the calcium ions are pumped from the sarcomere and back into storage in the sarcoplasmic reticulum. There are approximately 639 ...
"Topology of the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (RyR1)". Proceedings of the National Academy of ... Ry receptors occur primarily in muscle cell sarcoplasmic reticular (SR) membranes, and IP3 receptors occur primarily in brain ... Tetrameric cardiac and skeletal muscle sarcoplasmic reticular ryanodine receptors (RyR) are large (~2.3 MDa). The complexes ...
... chronic stimulation of Epac2 may be a cause of cardiac arrhythmia through CaMKII-dependent diastolic sarcoplasmic reticulum (SR ... "Epac2 mediates cardiac β1-adrenergic-dependent sarcoplasmic reticulum Ca2+ leak and arrhythmia". Circulation. 127 (8): 913-22. ...
Similar to the ER is the sarcoplasmic reticulum (SR) found only in muscle cells. The SR stores and pumps calcium ions. The SR ... 1 Nucleus 2 Nuclear pore 3 Rough endoplasmic reticulum (RER) 4 Smooth endoplasmic reticulum (SER) 5 Ribosome on the rough ER 6 ... Toyoshima C. et al (2000). "Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 A resolution". Nature 405 ( ... The endoplasmic reticulum is in cells that have a nucleus: in eukaryote cells but not in prokaryote cells. It takes these forms ...
Primary type Ia sensory fibers (large diameter) spiral around all intrafusal muscle fibres, ending near the middle of each fibre. Secondary type II sensory fibers (medium diameter) end adjacent to the central regions of the static bag and chain fibres.[2] These fibres send information by stretch-sensitive mechanically-gated ion-channels of the axons.[3] The motor part of the spindle is provided by motor neurons: up to a dozen gamma motor neurons and one or two beta motor neurons, collectively called fusimotor neurons.[citation needed] These activate the muscle fibres within the spindle. Gamma motor neurons supply only muscle fibres within the spindle, whereas beta motor neurons supply muscle fibres both within and outside of the spindle. Activation of the neurons causes a contraction and stiffening of the end parts of the muscle spindle muscle fibers. Fusimotor neurons are classified as static or dynamic according to the type of muscle fibers they innervate and their effects on the responses of ...
Calcium also comes out of a special place in the cell called the sarcoplasmic reticulum. This calcium sticks to the specialized ...
In a heart with AF, the increased calcium release from the sarcoplasmic reticulum and increased calcium sensitivity can lead to ...
... is a sheath of connective tissue that groups muscle fibers into bundles (anywhere between 10 and 100 or more) or fascicles. Studies of muscle physiology suggest that the perimysium plays a role in transmitting lateral contractile movements. This hypothesis is strongly supported in one exhibition of the existence of "perimysial junctional plates" in ungulate flexor carpi radialis muscles constructed by Emilie Passerieux.[1] The overall comprehensive organization of the perimysium collagen network, as well as its continuity and disparateness, however, have still not been observed and described thoroughly everywhere within the muscle. Found to have type I, III, VI, and XII collagen. ...
Calcium ions are then released from the sarcoplasmic reticulum into the sarcoplasm and subsequently bind to troponin. Troponin ... Active transport moves calcium ions back into the sarcoplasmic reticulum of the muscle fiber. ATP causes the binding between ... This depolarizes the muscle fiber membrane, and the impulse travels to the muscle's sarcoplasmic reticulum via the transverse ...
... stimuli result in a signal transduction cascade that leads to increased intracellular calcium from the sarcoplasmic reticulum ... basal level through a variety of protein pumps and calcium exchangers located on the plasma membrane and sarcoplasmic reticulum ...
Dens la cellulas muscularas que's presenta devath ua forma especilixada aperada reticulum sarcoplasmic. Los procès mecanics e ... aqueth tròç e reticulum endoplasmic que s'apera reticulum endoplasmic granulós (REG). L'aute estrèm d'aqueth organet que ... Lo reticulum endoplasmic (abreujat RE) qu'ei un organet de las cellulas eucariòtas banhant dens lo citoplasma e qui ei ... Citoplasma d'ua cellula eucariòta dab : (1) lo nuclèu, (2) los pòrs nuclears, (3) lo Reticulum endoplasmic granulós (RER), (4) ...
Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 A resolution. Nature. 405(6787):647-55. ... Endoplasmic reticulum: Structure and function. Prifysgol Meddygol Texas. (Saesneg) http://cellbio.utmb.edu/cellbio/rer1.htm ...
Increased amounts of Ca2+ also leads to increased storage of calcium in the sarcoplasmic reticulum, causing a corresponding ...
sarcoplasmic reticulum membrane. •receptor complex. Processo biológico. •response to hypoxia. •energy reserve metabolic process ... 2009). «Increased InsP3Rs in the junctional sarcoplasmic reticulum augment Ca2+ transients and arrhythmias associated with ... endoplasmic reticulum membrane. •plasma membrane. •cell cortex. •membrane. •integral component of membrane. •platelet dense ...
... s are skeletal muscle fibers that serve as specialized sensory organs (proprioceptors) that detect the amount and rate of change in length of a muscle.[1] They constitute the muscle spindle and are innervated by both sensory (afferent) and motor (efferent) fibers. Gamma efferents from small multipolar cells from anterior gray column innervate it. These form a part of neuromuscular spindles. Intrafusal muscle fibers are walled off from the rest of the muscle by an outer connective tissue sheath consisting of flattened fibroblasts and collagen.[2] This sheath has a spindle or "fusiform" shape, hence the name "intrafusal". There are two types of intrafusal muscle fibers: nuclear bag and nuclear chain fibers. They bear two types of sensory ending, known as annulospiral and flower-spray endings. Both ends of these fibers contract but the central region only stretches and does not contract. They are innervated by gamma motor neurons and beta motor neurons. It is by the sensory ...
Sarcoplasmic Reticulum Ca2+ release channel or Ryanodine receptor (Ryr) co-localizes with the muscle AKAP. RyR phosphorylation ...
The sarcoplasmic reticulum, a specialized type of smooth endoplasmic reticulum, forms a network around each myofibril of the ... When the action potential reaches the sarcoplasmic reticulum it triggers the release of Ca2+ from the Ca2+ channels. The Ca2+ ... The sarcoplasmic reticulum serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it ... Very quickly Ca2+ is actively transported back into the sarcoplasmic reticulum, which blocks the interaction between the thin ...
The other component, orthogonal to the direction of action of the muscle (Orthogonal force = Total force × sinΦ) is not exerted on the tendon, but simply squeezes the muscle, by pulling its aponeuroses toward each other. Notice that, although it is practically convenient to compute PCSA based on volume or mass and fiber length, PCSA (and therefore the total fiber force, which is proportional to PCSA) is not proportional to muscle mass or fiber length alone. Namely, the maximum (tetanic) force of a muscle fiber simply depends on its thickness (cross-section area) and type. By no means it depends on its mass or length alone. For instance, when muscle mass increases due to physical development during childhood, this may be only due to an increase in length of the muscle fibers, with no change in fiber thickness (PCSA) or fiber type. In this case, an increase in mass does not produce an increase in force. Sometimes, the increase in mass is associated with an increase in thickness. Only in this ...
... the sarcoplasmic reticulum. Activation of the ryanodine receptor causes calcium to be released from the sarcoplasmic reticulum ... As T-tubules bring the sarcolemma very close to the sarcoplasmic reticulum at all regions throughout the cell, calcium can then ... T-tubule structure and relationship to the sarcoplasmic reticulum in skeletal muscle ... and their stimulation increases calcium release from the sarcoplasmic reticulum.[14] Calcium control[edit]. As the space within ...
... formed by a T tubule surrounded by sarcoplasmic reticulum Unhappy triad, tearing of one or both of the cruciate ligaments, ...
... of the nanomolar-level binding is that ryanodine causes release of calcium from calcium stores as the sarcoplasmic reticulum in ...
... and so releases Ca2+ ions from the muscle fibre's sarcoplasmic reticulum. The action potentials that cause this require also ...
... in the sarcoplasmic reticulum (SR), causes opening of the RYR. In cardiac muscle, opening of the L-type calcium channel permits ... Furthermore, the AID sequence does not appear to contain an endoplasmic reticulum retention signal, and this may be located in ... "The I-II loop of the Ca2+ channel α1 subunit contains an endoplasmic reticulum retention signal antagonized by the beta subunit ... the final α1 subunit conformation and delivering it to the cell membrane by its ability to mask an endoplasmic reticulum ...
... it contains a sarcoplasmic reticulum. The sarcoplasmic reticulum surrounds the myofibrils and holds a reserve of the calcium ... Once a cell is sufficiently stimulated, the cell's sarcoplasmic reticulum releases ionic calcium (Ca2+), which then interacts ... T tubules are the pathways for action potentials to signal the sarcoplasmic reticulum to release calcium, causing a muscle ...
... sarcoplasmic reticulum. Immediately after muscle contraction, intracellular Ca²⁺ is quickly returned to its normal ... and a calcium pump in sarcoplasmic reticulum, causing the muscle to relax. ...
The sarcoplasmic reticulum (SR), from the Greek σάρξ sarx ("flesh"), is smooth ER found in myocytes. The only structural ... 1 Nucleus 2 Nuclear pore 3 Rough endoplasmic reticulum (RER) 4 Smooth endoplasmic reticulum (SER) 5 Ribosome on the rough ER 6 ... The sarcoplasmic reticulum plays a major role in excitation-contraction coupling.[22] ... Toyoshima C, Nakasako M, Nomura H, Ogawa H (June 2000). "Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 ...
Chadwick, D. (2002). Role of the sarcoplasmic reticulum in smooth muscle. John Wiley and Sons. pp. 259-264. ISBN 978-0-470- ...
Sarcoplasmic reticulum little elaborated moderately elaborated highly elaborated ATPase little moderate abundant ...
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the endoplasmic ... The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct ... The cytosolic side of the pump then closes and the sarcoplasmic reticulum side opens, releasing the Ca2+ into the SR.[6] ... The breakdown of the sarcoplasmic reticulum, along with the resultant release of calcium, is an important contributor to rigor ...
... sarcoplasmic reticulum; Golgi apparatus; lysosome; mitochondrion (inner and outer membranes); nucleus (inner and outer ... In eucaryotic cells, new phospholipids are manufactured by enzymes bound to the part of the endoplasmic reticulum membrane that ... Distinct types of membranes also create intracellular organelles: endosome; smooth and rough endoplasmic reticulum; ...
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the endoplasmic ... The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct ... The cytosolic side of the pump then closes and the sarcoplasmic reticulum side opens, releasing the Ca2+ into the SR. A protein ... Mechanisms of caffeine activation of single calcium-release channels of sheep cardiac sarcoplasmic reticulum. J Physiol (Lond) ...
Calcium-transporting ATPase sarcoplasmic reticulum type, fast-twitch skeletal muscle isoform; Endoplasmic... ... Calcium-transporting ATPase sarcoplasmic reticulum type, fast-twitch skeletal muscle isoform; Endoplasmic reticulum class 1/2 ... Crystal structure of sarcoplasmic reticulum Ca2+-ATPase (SERCA) from bovine muscle. J Struct Biol. 2012;178:38-44.PubMed ... The Ca2+ is released from the sarcoplasmic reticulum by ryanodine receptor and taken back to the SR by SERCA pumps. The idea of ...
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the endoplasmic ... The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct ... The cytosolic side of the pump then closes and the sarcoplasmic reticulum side opens, releasing the Ca2+ into the SR.[6] ... The breakdown of the sarcoplasmic reticulum, along with the resultant release of calcium, is an important contributor to rigor ...
sarcoplasmic reticulum synonyms, sarcoplasmic reticulum pronunciation, sarcoplasmic reticulum translation, English dictionary ... definition of sarcoplasmic reticulum. n. The form of endoplasmic reticulum found in striated muscle fibers. n. a network of ... sarcoplasmic reticulum. Also found in: Thesaurus, Medical, Acronyms, Encyclopedia, Wikipedia. sarcoplasmic reticulum. n.. The ... Ryanodine binds to CRAC in the sarcoplasmic reticulum of cardiac and skeletal muscles as well as to the endoplasmic reticulum ...
The function of the sarcoplasmic reticulum is to store and release calcium ions in the bodys muscle cells, according to the Dr ... The sarcoplasmic reticulum is similar in structure to the endoplasmic reticulum, except for the assortment of proteins it ... The sarcoplasmic reticulum stores large amounts of calcium and then releases it when muscles become stimulated, but the ... The function of the sarcoplasmic reticulum is to store and release calcium ions in the bodys muscle cells, according to the Dr ...
The binding of [3H]ryanodine with cardiac sarcoplasmic reticulum vesicles depends on the calcium concentration. Binding in the ... The interaction of calcium and ryanodine with cardiac sarcoplasmic reticulum.. Alderson BH, Feher JJ. ... for closure of the calcium release channel and the subsequent increase in the calcium uptake rate of the sarcoplasmic reticulum ...
Anthony Martonosi presents general information about the development and function of the sarcoplasmic reticulum within a ... Sarcoplasmic reticulum is a form of endoplasmic reticulum found in large quantities in mature muscle cells. ... Sarcoplasmic reticulum is a form of endoplasmic reticulum found in large quantities in mature muscle cells. Anthony Martonosi ... Focusing on the development of the sarcoplasmic reticulum, Martonosi demonstrates the regulatory functions that control the ...
Sarcoplasmic Reticulum. Some articles on reticulum, sarcoplasmic reticulum:. Muscle Fibers - Structure of Skeletal Muscle Fiber ... While the muscle fiber does not have a smooth endoplasmic reticulum, it contains a sarcoplasmic reticulum ... The sarcoplasmic ... Smooth Endoplasmatic Recticulum - Structure - Smooth Endoplasmic Reticulum - Sarcoplasmic Reticulum. ... The sarcoplasmic ... while the sarcoplasmic reticulum stores and pumps calcium ions .... Sarcolipin - Function. ... Sarcoplasmic reticulum Ca2+- ...
S-ER stands for Sarcoplasmic and Endoplasmic Reticulum. S-ER is defined as Sarcoplasmic and Endoplasmic Reticulum rarely. ... www.acronymfinder.com/Sarcoplasmic-and-Endoplasmic-Reticulum-(S_ER).html,S-ER,/a,. ... www.acronymfinder.com/Sarcoplasmic-and-Endoplasmic-Reticulum-(S_ER).html ... www.acronymfinder.com/Sarcoplasmic-and-Endoplasmic-Reticulum-(S_ER).html ...
... on WN Network delivers the latest Videos and Editable pages for News & Events, including Entertainment, ... Latest News for: sarcoplasmic reticulum. Edit Mechanism of the E2 to E1 transition in Ca2+ pump revealed by crystal structures ... H. Kirk Hammond and Dr ... Dr ... intracoronary delivery of adeno-associated virus type 1 encoding sarcoplasmic reticulum Ca2+- ... Endoplasmic reticulum. The endoplasmic reticulum (ER) is a type of organelle in the cells of eukaryotic organisms that forms an ...
Catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen ...
This view shows a one-sarcomere length of sarcoplasmic reticulum in three intermyofibrillar clefts. The high development of the ... reticulum is related to the rapid contraction and relaxation of this muscle. (Enhancement of 9N1956) - Stock Image C003/5275 ... This view shows a one-sarcomere length of sarcoplasmic reticulum in three intermyofibrillar clefts. The high development of the ... sarcoplasmic reticulum, tem, toadfish cell, toadfish swim bladder, transmission electron micrograph, transmission electron ...
Human Sarcoplasmic Reticulum Human Sarcoplasmic Reticulum: Polyclonal Antibody - Calreticulin Antibody - Western Blotting, ... Category listing: Human tlr3 to Human Sarcoplasmic Reticulum Sort by: Popularity Our Choices All-Round Favorites Most Recent ...
The sarcoplasmic reticulum releases calcium ions during muscle contraction and absorb them during relaxation. ... The special type of smooth endoplasmic reticulum found in smooth and striated muscle fibers whose function is to store and ... Retrieved from "https://www.biology-online.org/dictionary/index.php?title=Sarcoplasmic_reticulum&oldid=94626" ...
This is what your skeletal muscles look like when they have been labeled with fluorescent antibodies against a sarcoplasmic/ ... endoplasmic reticulum calcium ATPase (SERCA). Notice the striations (skeletal muscle is striated muscle) and the nuclear ...
Sarcoplasmic Reticulum High Pressure Liquid Chromatography Partial Amino Acid Sequence Cardiac Sarcoplasmic Reticulum ... Tada, M., and Katz, A. M., 1982, Phosphorylation of the sarcoplasmic reticulum and sarcolemma, Annu. Rev. Physiol. 44:401-423. ... These are sarcolemma, sarcoplasmic reticulum (SR), and myofibrillar proteins. Information transfer among these systems is ... Tada, M., Kadoma, M., Inui, M., and Fujii, J., 1988, Regulation of Ca2+ pump from cardiac sarcoplasmic reticulum, Methods ...
The sarcoplasmic reticulum (SR) of muscle cells is a specialized form of the endoplasmic reticulum (ER) dedicated to storage ... 2003) Distribution of the endoplasmic reticulum and its relationship with the sarcoplasmic reticulum in skeletal myofibers. Exp ... The sarcoplasmic reticulum (SR) of skeletal muscle cells is a complex network of tubules and cisternae that share a common ... 2008) The sarcoplasmic reticulum: An organized patchwork of specialized domains. Traffic 9:1044-1049. ...
Alteration of Sarcoplasmic Reticulum ,svg style=vertical-align:-0.26999pt;width:42.4375px; id=M1 height=21.1875 version= ... Alteration of Sarcoplasmic Reticulum Release in Skeletal Muscle from Calpain 3-Deficient Mice. Figure 4. Effect of caffeine and ...
Transports calcium ions from the cytosol into the sarcoplasmic/endoplasmic reticulum lumen. Contributes to calcium ... Endoplasmic reticulum, Membrane, Nucleus, Sarcoplasmic reticulum. ,p>This section provides information on the disease(s) and ... Sarcoplasmic/endoplasmic reticulum calcium ATPase 3Add BLAST. 999. Amino acid modifications. Feature key. Position(s). ... Sarcoplasmic/endoplasmic reticulum calcium ATPase 3Curated (EC:7.2.2.10*Search proteins in UniProtKB for this EC number. ...
Phospholamban (PLN) is a 52 amino acid integral membrane protein of the sarcoplasmic reticulum (SR) that exists in both ... Phospholamban phosphorylation increases the passive calcium leak from cardiac sarcoplasmic reticulum.. [Roozbeh Aschar-Sobbi, ...
SR, sarcoplasmic reticulum. Heart disease is the leading cause of death among diabetic patients. It has been recognized for a ... Sarcoplasmic reticulum calcium leakage.. In addition to observing calcium transients in control and diabetic mice, we also ... Kim HW, Ch YS, Lee HR, Park SY, Kim YH: Diabetic alterations in cardiac sarcoplasmic reticulum Ca2+-ATPase and phospholamban ... Trost SU, Belke DD, Bluhm WF, Meyer M, Swanson E, Dillmann WH: Overexpression of the sarcoplasmic reticulum Ca2+-ATPase ...
ROLE OF THE SARCOPLASMIC RETICULUM IN GLYCOGEN METABOLISM. Jean-Claude Wanson, Pierre Drochmans ... derived from the sarcoplasmic reticulum, and of small particles 10-20 mµ in diameter attached to the outer surface of the ... Sarcoplasmic vesicles and ß-glycogen particles 30-40 mµ in diameter were isolated from perfused rabbit skeletal muscle by the ... The presence of binding sites between the membranes of the sarcoplasmic vesicles and a glycogen-enzyme complex suggests that ...
Russ M, Reinauer H, Eckel J: Diabetes-induced decrease in the mRNA coding for sarcoplasmic reticulum Ca(2+)-ATPase in adult rat ... Overexpression of the Sarcoplasmic Reticulum Ca2+-ATPase Improves Myocardial Contractility in Diabetic Cardiomyopathy ... Limas CJ, Olivari MT, Goldenberg IF, Levine TB, Benditt DG, Simon A: Calcium uptake by cardiac sarcoplasmic reticulum in human ... Overexpression of the Sarcoplasmic Reticulum Ca2+-ATPase Improves Myocardial Contractility in Diabetic Cardiomyopathy ...
Palmitoyl-carnitine increases RyR2 oxidation and sarcoplasmic reticulum Ca2+ leak in cardiomyocytes: Role of adenine nucleotide ... and therefore increased sarcoplasmic reticulum (SR) Ca(2+) leak. ANT inhibition or anti-oxidant strategy (N-acetylcysteine) ...
ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 3), Authors: Dessen P. Published in: Atlas Genet Cytogenet Oncol ... ATPase activity organelle membrane platelet dense tubular network membrane nuclear membrane sarcoplasmic reticulum membrane ion ... ATPase activity organelle membrane platelet dense tubular network membrane nuclear membrane sarcoplasmic reticulum membrane ion ... in apoptotic process calcium ion transmembrane transporter activity integral component of membrane sarcoplasmic reticulum ...
Calcium entry into the cell is facilitated by the sarcoplasmic reticulum (SR). This book explores the latest research on the ... role of the sarcoplasmic reticulum (SR) in smooth muscle function. It examines the control and modulation of the SR and how ...
Sodium current-induced release of calcium from cardiac sarcoplasmic reticulum Message Subject. (Your Name) has forwarded a page ... The role of sodium-calcium exchange at the sarcolemma in the release of calcium from cardiac sarcoplasmic reticulum was ... sodium-calcium exchange may promote calcium entry into cardiac cells and trigger sarcoplasmic calcium release during ...
The organization of calcium (Ca2+) stores in the sarcoplasmic and endoplasmic reticulum (S-ER) is poorly understood. The ... Spatially and Functionally Distinct Ca2+ Stores in Sarcoplasmic and Endoplasmic Reticulum Message Subject. (Your Name) has ... Spatially and Functionally Distinct Ca2+ Stores in Sarcoplasmic and Endoplasmic Reticulum ... Spatially and Functionally Distinct Ca2+ Stores in Sarcoplasmic and Endoplasmic Reticulum ...
... counteracting the slowing of sarcoplasmic reticulum Ca2+ uptake in such mice by releasing sarco(endo)plasmic reticulum Ca2+- ... However, even sarcoplasmic reticulum Ca2+ uptake rates that are faster than normal are not sufficient to prevent the ... Re-evaluating sarcoplasmic reticulum function in heart failure. Nat Med. 2000; 6: 942-943. ... Chronic phospholamban-sarcoplasmic reticulum calcium ATPase interaction is the critical calcium cycling defect in dilated ...
What is sarcoplasmic reticulum calcium release channel? Meaning of sarcoplasmic reticulum calcium release channel medical term ... What does sarcoplasmic reticulum calcium release channel mean? ... Looking for online definition of sarcoplasmic reticulum calcium ... release channel in the Medical Dictionary? sarcoplasmic reticulum calcium release channel explanation free. ... Sarcoplasmic reticulum calcium release channel , definition of sarcoplasmic reticulum calcium release channel by Medical ...
  • Arruda AP, Ketzer LA, Nigro M, Galina A, Carvalho DP, de Meis L. Cold tolerance in hypothyroid rabbits: role of skeletal muscle mitochondria and sarcoplasmic reticulum Ca2+ ATPase isoform 1 heat production. (springer.com)
  • Adult forms of the Ca2+ATPase of sarcoplasmic reticulum. (springer.com)
  • Altered mRNA splicing of the skeletal muscle ryanodine receptor and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase in myotonic dystrophy type 1. (springer.com)
  • Amino-acid sequence of a Ca2+ + Mg2+-dependent ATPase from rabbit muscle sarcoplasmic reticulum, deduced from its complementary DNA sequence. (springer.com)
  • Mutations in the gene-encoding SERCA1, the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase, are associated with Brody disease. (springer.com)
  • Crystal structure of sarcoplasmic reticulum Ca2+-ATPase (SERCA) from bovine muscle. (springer.com)
  • Sahoo SK, Shaikh SA, Sopariwala DH, Bal NC, Periasamy M. Sarcolipin protein interaction with sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) is distinct from phospholamban protein, and only sarcolipin can promote uncoupling of the SERCA pump. (springer.com)
  • Toyoshima C. How Ca2+-ATPase pumps ions across the sarcoplasmic reticulum membrane. (springer.com)
  • Zádor E, Kósa M. The neonatal sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA1b): a neglected pump in scope. (springer.com)
  • Popov, "Differences in the force-interval relationship of isolated human myocardium with chronic coronary artery disease with and without type 2 diabetes mellitus and the role of sarcoplasmic reticulum [Ca.sup.2+]-ATPase," Human Physiology, vol. (thefreedictionary.com)
  • Astragaloside IV improved intracellular calcium handling in hypoxia-reoxygenated cardiomyocytes via the sarcoplasmic reticulum [Ca.sup.2+]-ATPase," Pharmacology, vol. (thefreedictionary.com)
  • Ca2 +-ATPase of sarcoplasmic reticulum (SERCA1a) pumps two Ca2+ per ATP hydrolyzed from the cytoplasm and two or three protons in the opposite direction. (wn.com)
  • Key regulator of striated muscle performance by acting as the major Ca(2+) ATPase responsible for the reuptake of cytosolic Ca(2+) into the sarcoplasmic reticulum. (rcsb.org)
  • A dysfunctioning of Ca2+ pump ATPase in the sarcoplasmic reticulum in vascular smooth muscle has been proposed as a contributing factor for the development of genetic hypertension. (ahajournals.org)
  • This is what your skeletal muscles look like when they have been labeled with fluorescent antibodies against a sarcoplasmic/ endoplasmic reticulum calcium ATPase (SERCA). (davidson.edu)
  • Three novel sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) 3 isoforms. (uniprot.org)
  • The type 1 diabetic model is associated with a depression in contractile function underlined primarily by reduced sequestration of calcium into the sarcoplasmic reticulum (SR) as a result of decreased sarcoendoplasmic reticular Ca 2+ -ATPase (SERCA) pump activity. (diabetesjournals.org)
  • Background- Low activity of the sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA2a) resulting from strong inhibition by phospholamban (PLN) can depress cardiac contractility and lead to dilated cardiomyopathy and heart failure. (ahajournals.org)
  • 4 PLN is a small transmembrane protein located in the sarcoplasmic reticulum (SR) that regulates the activity of the sarco(endo)plasmic reticulum Ca 2+ -ATPase isoform 2a (SERCA2a). (ahajournals.org)
  • Here we have solved the crystal structure of the calcium ATPase of skeletal muscle sarcoplasmic reticulum (SERCA1a) at 2.6 A resolution with two calcium ions bound in the transmembrane domain, which comprises ten alpha-helices. (nih.gov)
  • Rationale: Modulation of the activity of sarcoendoplasmic reticulum calcium ATPase (SERCA) can profoundly affect Ca21 homeostasis. (ku.edu)
  • The steady-state ATPase activity of sarcoplasmic-reticulum (Ca(2+)-Mg2+)-ATPase is inhibited by thapsigargin at a molar ratio of 1:1, with a dissociation constant for thapsigargin estimated to be in the sub-nanomolar range. (biochemj.org)
  • The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. (biochemj.org)
  • It is concluded that measurement of the Ca2+-dependent phosphorylation allows rapid and reproducible quantification of the concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum. (biochemj.org)
  • The data suggested that the phosphoprotein of the Ca-dependent ATPase formed from Pi represented a high-energy intermediate of the reverse reaction of the Ca pump of cardiac sarcoplasmic reticulum. (eurekamag.com)
  • Abstract -Cardiac hypertrophy and heart failure are known to be associated with a reduction in Ca 2+ -ATPase pump levels of the sarcoplasmic reticulum (SR). To determine whether, and to what extent, alterations in Ca 2+ pump numbers can affect contraction and relaxation parameters of the heart, we have overexpressed the cardiac SR Ca 2+ -ATPase specifically in the mouse heart using the α-myosin heavy chain promoter. (ahajournals.org)
  • Analysis of 2 independent transgenic lines demonstrated that sarco(endo)plasmic reticulum Ca 2+ -ATPase isoform (SERCA2a) mRNA levels were increased 3.88±0.4-fold and 7.90±0.2-fold over those of the control mice. (ahajournals.org)
  • The Ca 2+ uptake function of the SR is driven by an ATP-dependent Ca 2+ transport pump, the sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA). (ahajournals.org)
  • As a major Ca 2+ pump in the sarcoplasmic reticulum of the cardiomyocyte, SERCA2a (sarcoplasmic/endoplasmic reticulum Ca 2+ -ATPase 2a) controls the relaxation and contraction of the cardiomyocyte. (biochemsoctrans.org)
  • Immunohistochemical studies revealed subsarcolemmal immunoreactivity for sarco/endoplasmic reticulum Ca2+-ATPase 1 (SERCA 1) in the longitudinal SR, but no immunoreactivity for calsequestrin in the terminal cisternae or type 1 ryanodine receptor (RYR1) in the junctional SR. Muscles biopsied from 2 patients with TAs showed immunoreactivity not only for SERCA1 but also for other SR proteins, including calsequestrin and RYR1. (ovid.com)
  • Recognizes canine SERCA2a (sarcoplasmic/endoplasmic reticulum calcium ATPase 2a) and SERCA2b isoforms. (mybiosource.com)
  • In heart failure, a reduction in Ca transient amplitude and contractile dysfunction can by caused by Ca leak through the sarcoplasmic reticulum (SR) Ca channel (ryanodine receptor, RyR) and/or decreased activity of the SR Ca ATPase (SERCA). (salford.ac.uk)
  • Cloning, characterization, and expression patterns of three sarco/endoplasmic reticulum Ca2+-ATPase isoforms from pearl oyster (Pinctada fucata). (uni-bielefeld.de)
  • In addition, the content of several key Ca 2+ handling proteins, including two isoforms of the sarco(endo)plasmic reticulum ATPase pump (SERCA 1 & 2), ryanodine receptor type 1 (RyR1), parvalbumin, and calsequestrin were determined by Western analysis. (vt.edu)
  • Reconstitution of a Ca2+-transporting ATPase system from triton X-100-solubilized sarcoplasmic reticulum. (ox.ac.uk)
  • Dux, L , Papp, S & Martonosi, A 1985, ' Conformational responses of the tryptic cleavage products of the Ca 2+ -ATPase of sarcoplasmic reticulum ', Journal of Biological Chemistry , vol. 260, no. 25, pp. 13454-13458. (elsevier.com)
  • Sarcoplasmic reticulum (SR) Ca 2+ -adenosine triphosphatase (ATPase) mRNA expression is reduced in the failing human myocardium. (elsevier.com)
  • It is unknown whether the transmural heterogeneity of sarcoplasmic reticulum (SR) Ca 2+ -ATPase gene expression is present within the left ventricular (LV) wall. (elsevier.com)
  • We have synthesized a new class of photoaffinity analogs, 2',3'-O-(2,4,6-trinitrophenyl)-8-azido-ATP, -ADP and -AMP (TNP- 8N₃ATP, -ADP and -AMP), and their radiolabeled derivatives, and characterized their interaction with the sarcoplasmic reticulum Ca²⁺-ATPase. (uct.ac.za)
  • Overexpression of the rat sarcoplasmic reticulum Ca2+ ATPase gene in the heart of transgenic mice accelerates calcium transients and cardiac relaxation. (duke.edu)
  • The Ca2+ ATPase of the sarcoplasmic reticulum (SERCA2) plays a dominant role in lowering cytoplasmic calcium levels during cardiac relaxation and reduction of its activity has been linked to delayed diastolic relaxation in hypothyroid and failing hearts. (duke.edu)
  • Differential changes in cardiac phospholamban and sarcoplasmic reticular Ca(2+)-ATPase protein levels. (meta.org)
  • The ATP2A2 gene provides instructions for making an enzyme called sarco(endo)plasmic reticulum calcium-ATPase 2 (SERCA2). (nih.gov)
  • Miyauchi Y, Daiho T, Yamasaki K, Takahashi H, Ishida-Yamamoto A, Danko S, Suzuki H, Iizuka H. Comprehensive analysis of expression and function of 51 sarco(endo)plasmic reticulum Ca2+-ATPase mutants associated with Darier disease. (nih.gov)
  • These calcium pumps are called Sarco(endo)plasmic reticulum Ca2+ ATPases (SERCA). (wikipedia.org)
  • The cytosolic side of the pump then closes and the sarcoplasmic reticulum side opens, releasing the Ca2+ into the SR. A protein found in cardiac muscle, called phospholamban (PLB) has been shown to prevent SERCA from working. (wikipedia.org)
  • The Ca2+ is released from the sarcoplasmic reticulum by ryanodine receptor and taken back to the SR by SERCA pumps. (springer.com)
  • A structural and functional analysis of the closely related SERCA2b Ca 2+ pump, i.e. the housekeeping Ca 2+ pump found in the endoplasmic reticulum and the only SERCA isoform characterized by a high Ca 2+ affinity, aimed to fill this gap. (biochemsoctrans.org)
  • The ATP pumps that reside in intracellular organelles are encoded by a family of structurally related enzymes, termed the sarcoplasmic or endoplasmic reticulum calcium (SERCA) ATPases. (mybiosource.com)
  • This gene encodes one of the SERCA Ca(2+)-ATPases, which are intracellular pumps located in the sarcoplasmic or endoplasmic reticula of muscle cells. (nih.gov)
  • The form of endoplasmic reticulum found in striated muscle fibers. (thefreedictionary.com)
  • The special type of smooth endoplasmic reticulum found in smooth and striated muscle fibers whose function is to store and release calcium ions. (biology-online.org)
  • reported that an increased mitochondrial calcium content (induced by LPS) was associated with reduced calcium uptake by and increased calcium leakage from the sarcoplasmic reticulum and it was also associated with decreased [DELTA]p, mitochondrial uncoupling, altered state 3 respiration, and impaired RCR. (thefreedictionary.com)
  • The data obtained support the hypothesis that ryanodine binding to the low-affinity site (Km about 17 microM) is responsible for closure of the calcium release channel and the subsequent increase in the calcium uptake rate of the sarcoplasmic reticulum. (nih.gov)
  • PLN −/− +TgPLN R9C hearts demonstrated accelerated sarcoplasmic reticulum Ca 2+ uptake rates and improved hemodynamics compared with PLN +/+ +TgPLN R9C mice but still responded poorly to β-adrenergic stimulation because PLN R9C impairs protein kinase A-mediated phosphorylation of both wild-type and mutant PLN. (ahajournals.org)
  • The National Institutes of Health study points out that researchers have expanded the explanation of the sarcoplasmic reticulum's functions to include homeostasis and contribution to signaling in other organelles such as the nucleus and mitochondria. (reference.com)
  • GENERAL SIGNIFICANCE: The present study reports profound morphological changes in cancer cachectic muscle, which are visualized mainly in alterations in sarcoplasmic reticulum and mitochondria. (lu.se)
  • Physical and Functional Cross Talk Between Endo-Sarcoplasmic Reticulum and Mitochondria in Skeletal Muscle. (cam.ac.uk)
  • The physiological relevance of contacts between the sarcoplasmic reticulum (SR), a specialized domain of the endoplasmic reticulum (ER) in skeletal muscle, and mitochondria is still not clear. (cam.ac.uk)
  • Bassani, JWM, Bassani, RA & Bers, DM 1993, ' Ca 2+ cycling between sarcoplasmic reticulum and mitochondria in rabbit cardiac myocytes ', Journal of Physiology , vol. 460, pp. 603-621. (elsevier.com)
  • Catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen (By similarity). (rcsb.org)
  • Transports calcium ions from the cytosol into the sarcoplasmic/endoplasmic reticulum lumen. (uniprot.org)
  • This enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen, and is involved in calcium sequestration associated with muscular excitation and contraction. (nih.gov)
  • In eucaryotic cells, new phospholipids are manufactured by enzymes bound to the part of the endoplasmic reticulum membrane that faces the cytosol. (wikipedia.org)
  • SERCA1 truncated proteins unable to pump calcium reduce the endoplasmic reticulum calcium concentration and induce apoptosis. (springer.com)
  • In addition to being a calcium storage mechanism, the sarcoplasmic reticulum was originally thought to be synthetic and a storage mechanism for contractile proteins. (reference.com)
  • The sarcoplasmic reticulum is similar in structure to the endoplasmic reticulum, except for the assortment of proteins it contains, says Wikipedia. (reference.com)
  • The sarcoplasmic reticulum stores large amounts of calcium and then releases it when muscles become stimulated, but the endoplasmic reticulum mainly synthesizes and transports proteins to a cell system known as the Golgi apparatus. (reference.com)
  • The Synthesis and Insertion of Lumenal Sarcoplasmic Reticulum Proteins During Development of Skeletal Muscle 5. (routledge.com)
  • The Role of Ca in the Expression of the Endoplasmic Reticulum Chaperon Proteins GRP78(BiP) and GRP94 12. (routledge.com)
  • These are sarcolemma, sarcoplasmic reticulum (SR), and myofibrillar proteins. (springer.com)
  • Sarcoplasmic reticulum proteins in heart failure. (semanticscholar.org)
  • Levels of sarcoplasmic reticulum (SR) proteins and sarcolemmal Na(+)-Ca2+ exchanger were analyzed by Western blot in failing and nonfailing human myocardium and related to myocardial function. (semanticscholar.org)
  • However, the specific contribution of Casq2 deficiency to the arrhythmia phenotype is difficult to assess because Casq2-/- mice also show significant reductions in the sarcoplasmic reticulum (SR) proteins junctin and triadin-1 and increased SR volume. (biomedsearch.com)
  • To clarify the nature of CSs, we characterized the sarcoplasmic reticulum (SR) and other intracellular membrane system proteins in CSs of muscle biopsies from 2 adult Chinese siblings. (ovid.com)
  • The smooth endoplasmic reticulum lacks ribosomes and functions in lipid manufacture and metabolism, the production of steroid hormones , and detoxification . (wn.com)
  • The sarcoplasmic reticulum , a specialized type of smooth endoplasmic reticulum , forms a network around each myofibril of the muscle fiber. (wikipedia.org)
  • Abstract To investigate whether the energy derived from glycolysis is functionally coupled to Ca 2+ active transport in sarcoplasmic reticulum (SR), we determined whether glycolytic enzymes were associated with SR membranes and whether metabolism through these enzymes was capable of supporting 45 Ca transport. (ahajournals.org)
  • abstract = "The relationship between the ability of sarcoplasmic reticulum (SR) to accumulate and retain Ca2+ and the electrically stimulated contractions (ESCs) of isolated cells from guinea pig ventricular myocardium was investigated. (elsevier.com)
  • Phospholamban phosphorylation increases the passive calcium leak from cardiac sarcoplasmic reticulum. (sigmaaldrich.com)
  • Palmitoyl-carnitine increases RyR2 oxidation and sarcoplasmic reticulum Ca2+ leak in cardiomyocytes: Role of adenine nucleotide translocase. (nih.gov)
  • In addition, PC increased type 2 ryanodine receptor (RyR2) oxidation, S-nitrosylation and dissociation of FKBP12.6 from RyR2, and therefore increased sarcoplasmic reticulum (SR) Ca(2+) leak. (nih.gov)
  • Modest reductions of cardiac calsequestrin increase sarcoplasmic reticulum Ca2+ leak independent of luminal Ca2+ and trigger ventricular arrhythmias in mice. (biomedsearch.com)
  • ORCID: https://orcid.org/0000-0002-6459-523X , Eisner, DA and Venetucci, L 2016, 'Biphasic decay of the Ca transient results from increased sarcoplasmic reticulum Ca leak' , The Journal of Physiology, 594 (3) , pp. 611-623. (salford.ac.uk)
  • Spontaneous calcium waves in cardiac myocytes are caused by diastolic sarcoplasmic reticulum release (SR Ca 2+ leak) through ryanodine receptors. (elsevier.com)
  • Focusing on the development of the sarcoplasmic reticulum, Martonosi demonstrates the regulatory functions that control the production of its molecular components and investigates the interaction of these lipid and protein molecules with the myogenic, neurogenic and hormonal stimuli present in developing muscle cells. (routledge.com)
  • Regulation of Sarcoplasmic Reticulum Protein Composition and Turnover by Proteolysis 6. (routledge.com)
  • The outer ( cytosolic ) face of the rough endoplasmic reticulum is studded with ribosomes that are the sites of protein synthesis . (wn.com)
  • Phospholamban (PLN) is a 52 amino acid integral membrane protein of the sarcoplasmic reticulum (SR) that exists in both monomeric and pentameric forms. (sigmaaldrich.com)
  • Polyacrylamide gel electrophoresis (performed with phenol/acetic acid/water) of sarcoplasmic reticulum phosphorylated by [32P]-Pi demonstrated that the phosphate incorporation occurred into a protein with a MW of about 100,000, as in the case of phosphoprotein formation from ATP. (eurekamag.com)
  • Below are the list of possible Junctional sarcoplasmic reticulum protein products. (mybiosource.com)
  • Cardiac calsequestrin (Casq2) is thought to be the key sarcoplasmic reticulum (SR) Ca 2+ storage protein essential for SR Ca 2+ release in mammalian heart. (elsevier.com)
  • The endoplasmic reticulum is a structure inside the cell that is involved in protein processing and transport. (nih.gov)
  • Close physical association of CaV1.1 L-type calcium channels (LTCCs) at the sarcolemmal junctional membrane (JM) with ryanodine receptors (RyRs) of the sarcoplasmic reticulum (SR) is crucial for excitation-contraction coupling ( ECC ) in skeletal muscle. (wn.com)
  • CRUs are formed by clusters of channels called ryanodine receptors on the sarcoplasmic reticulum (SR) within the cardiomyocyte. (biologists.org)
  • In vascular smooth muscle cells, Ca2+ release via IP3 receptors (IP3R) and ryanodine receptors (RyR) on the sarcoplasmic reticulum (SR) Ca2+ store contributes significantly to the regulation of cellular events such as gene regulation, growth and contraction. (strath.ac.uk)
  • This study examined the effects of quinidine, quinine, and the quaternary quinidine derivative, quinidinium, on the conductance and activity of purified cardiac sarcoplasmic reticulum calcium release channels/ryanodine receptors (RyR) incorporated into planar lipid bilayers. (aspetjournals.org)
  • The sarcoplasmic reticulum (SR) Ca 2+ release channels/ryanodine receptors (RyR) play a vital role in the initiation of cellular contraction (for a review, see Meissner, 1994 ). (aspetjournals.org)
  • Inside the muscle's sarcoplasmic reticulum DHP receptors open channels and release calcium into the cell's cytoplasm. (sciencesource.com)
  • receptors change shape, causing them to physically pull on ryanodine receptors of the sarcoplasmic reticulum. (sciencesource.com)
  • Determine the mechanisms by which altered gating of ryanodine receptors can increase the risk of arrhythmia despite reduced sarcoplasmic reticulum calcium content. (grantome.com)
  • The sarcoplasmic reticulum (SR) of skeletal muscle cells is a complex network of tubules and cisternae that share a common lumen delimited by a single continuous membrane. (pnas.org)
  • The lacy membranes of the endoplasmic reticulum were first seen in 1945 using electron microscopy . (wn.com)
  • This latter fraction consists of vesicles, derived from the sarcoplasmic reticulum, and of small particles 10-20 mµ in diameter attached to the outer surface of the membranes. (rupress.org)
  • The presence of binding sites between the membranes of the sarcoplasmic vesicles and a glycogen-enzyme complex suggests that this association plays a role in the glycogenolysis during muscle contraction. (rupress.org)
  • In CF cells, SERCA2 interacted with Bcl-2, leading to its displacement from caveolae-related domains of endoplasmic reticulum membranes, as demonstrated in sucrose density gradient centrifugation and immunoprecipitation studies. (ku.edu)
  • Membranes of sarcoplasmic reticulum prepared from dog hearts were phosphorylated by [32P]-Pi in the presence of a Ca load and Mg. The [32P]phosphate incorporation into sarcoplasmic reticulum followed Michaelis-Menten kinetics with an apparent Km of 0.5 mM for Pi (pH 7.0). (eurekamag.com)
  • The open-channel conductance properties of a voltage-gated channel from sarcoplasmic reticulum were studied in planar phospholipid membranes. (rupress.org)
  • The role of the sarcoplasmic reticulum of smooth muscles may change as the body changes physiological states or experiences illness and disease, reports a study published by the National Center for Biotechnology Information. (reference.com)
  • Calcium entry into the cell is facilitated by the sarcoplasmic reticulum (SR). This book explores the latest research on the role of the sarcoplasmic reticulum (SR) in smooth muscle function. (cmu.ac.th)
  • Buy Role of the Sarcoplasmic Reticulum in Smooth Muscle by Novartis Foundation from Australia's Online Independent Bookstore, Boomerang Books. (boomerangbooks.com.au)
  • We'd like to know what you think about it - write a review about Role of the Sarcoplasmic Reticulum in Smooth Muscle book by Novartis Foundation and you'll earn 50c in Boomerang Bucks loyalty dollars (you must be a Boomerang Books Account Holder - it's free to sign up and there are great benefits! (boomerangbooks.com.au)
  • Sarcoplasmic reticulum is a form of endoplasmic reticulum found in large quantities in mature muscle cells. (routledge.com)
  • Ionic selectivity, saturation, and block in a K+-selective channel from sarcoplasmic reticulum. (rupress.org)
  • Toyoshima C, Nakasako M, Nomura H, Ogawa H. Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 A resolution. (springer.com)
  • Effects of sarcoplasmic reticulum calcium pump inhibitors on vascular smooth muscle. (ahajournals.org)
  • In this study, we determined whether in vitro inhibition of the sarcoplasmic reticulum Ca2+ pump in vascular smooth muscle tissues and cultured cells isolated from aortas of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats would elicit the known alterations of contractile function and cell growth. (ahajournals.org)
  • Russell Tupling, A. 2015-07-21 00:00:00 In a previous study, we reported lower sarcoplasmic reticulum (SR) Ca2+ pump ionophore ratios in rat soleus compared to red and white gastrocnemius (RG, WG) muscles which may be indicative of greater SR Ca2+ permeability in soleus. (deepdyve.com)
  • The phosphorylation of sarcoplasmic reticulum by [32P]-Pi was strongly inhibited by Ca in the medium. (eurekamag.com)
  • The role of sodium-calcium exchange at the sarcolemma in the release of calcium from cardiac sarcoplasmic reticulum was investigated in voltage-clamped, isolated cardiac myocytes. (sciencemag.org)
  • Numerous studies suggest a dysfunctional sarcoplasmic reticulum (SR), leading to altered intracellular calcium handling in cardiac myocytes, might be involved in the development of this disease. (diabetesjournals.org)
  • Background -The sarcoplasmic reticulum (SR) Ca 2+ -release channel plays a key role in the excitation-contraction coupling of cardiac myocytes. (ahajournals.org)
  • Within the cell, SERCA2 is found in the endoplasmic reticulum and a related structure in muscle cells called the sarcoplasmic reticulum. (nih.gov)
  • The binding of [3H]ryanodine with cardiac sarcoplasmic reticulum vesicles depends on the calcium concentration. (nih.gov)
  • Sarcoplasmic vesicles and ß-glycogen particles 30-40 mµ in diameter were isolated from perfused rabbit skeletal muscle by the differential precipitation-centrifugation method. (rupress.org)
  • Reactive disulfide compounds (RDSs) with a pyridyl ring adjacent to the S-S bond such as 2,2'-dithiodipyridine (2,2'-DTDP), 4,4'-dithiodipyridine, and N-succinimidyl 3(2-pyridyldithio)propionate (SPDP) trigger Ca 2+ release from sarcoplasmic reticulum (SR) vesicles. (elsevier.com)
  • The endoplasmic reticulum ( ER ) is a type of organelle in the cells of eukaryotic organisms that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures known as cisternae . (wn.com)
  • In addition, the transverse tubules were observed to be continuous across the width of the fiber, a set of flat intermediate cisternae was seen to connect the terminal cisternae to the longitudinal tubules in the A band, and the continuous reticulum collar at the center of the A band was found to be perforated by circular and elongated pores (the fenestrated collar). (rupress.org)
  • together these three components form the triads that exist within the network of the sarcoplasmic reticulum, in which each T tubule has two terminal cisternae on each side of it. (wikipedia.org)
  • A gene on chromosome 19q13.1 that encodes a ryanodine receptor found in skeletal muscle, which acts as a calcium channel connecting the sarcoplasmic reticulum and transverse tubules. (thefreedictionary.com)
  • Skeletal muscle contraction is triggered by Ca2 + release from the sarcoplasmic reticulum (SR) in response to plasma membrane (PM) excitation. (wn.com)
  • The high development of the reticulum is related to the rapid contraction and relaxation of this muscle. (sciencephoto.com)
  • The sarcoplasmic reticulum releases calcium ions during muscle contraction and absorb them during relaxation . (biology-online.org)
  • Skeletal muscle contraction depends on the release of Ca 2+ from the sarcoplasmic reticulum (SR), but the dynamics of the SR free Ca 2+ concentration ([Ca 2+ ] SR ), its modulation by physiological stimuli such as catecholamines, and the concomitant changes in cAMP handling have never been directly determined. (rupress.org)
  • The results are discussed in terms of a possible mechanism for a role of the transverse tubules and sarcoplasmic reticulum in excitation-contraction coupling, as suggested by their morphology and a variety of physiological studies. (rupress.org)
  • The sarcoplasmic reticulum assists with muscle contraction and relaxation by releasing and storing calcium ions. (nih.gov)
  • The sarcoplasmic reticulum serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it signals the sarcoplasmic reticulum to release calcium ions from the gated membrane channels to stimulate a muscle contraction. (wikipedia.org)
  • The Development of Sarcoplasmic Reticulum in Skeletal Muscle (SR) and the Expression of Ca-AT Pase 4. (routledge.com)
  • Differences in sarcoplasmic reticulum gene expression in myocardium from patients undergoing cardiac surgery. (meta.org)
  • One possibility is that disrupted calcium (Ca 2+ ) handling by the sarcoplasmic reticulum (SR) leads to an increased cytosolic Ca 2+ concentration that activates proteolytic and apoptotic pathways that initiate muscle fiber death. (vt.edu)
  • Conclusions- The data demonstrate an association between the dose-dependent inhibition of SERCA2a activity by PLN wt and the time of onset of heart failure and show that a weak inhibitor of SERCA2a, PLN R9C , which is diminished in its ability to modify the level of SERCA2a activity, leads to heart failure despite fast sarcoplasmic reticulum Ca 2+ reuptake. (ahajournals.org)
  • 1 Therefore, both Ca 2+ release from intracellular stores 3 and reuptake into the sarcoplasmic reticulum (SR) appear to be impaired. (ahajournals.org)
  • The sarcoplasmic reticulum (SR) is an intracellular membrane system which regulates this internal free Ca²⁺ concentration. (pdx.edu)
  • Anthony Martonosi presents general information about the development and function of the sarcoplasmic reticulum within a framework of contemporary research on the molecular biology of biosynthetic and signaling processes. (routledge.com)
  • Purification and properties of an adenosine triphosphatase from sarcoplasmic reticulum. (springer.com)
  • Molecular cloning and characterization of a Ca2+ + Mg2+-dependent adenosine triphosphatase from rat cardiac sarcoplasmic reticulum. (meta.org)
  • The function of the sarcoplasmic reticulum is to store and release calcium ions in the body's muscle cells, according to the Dr. Evangelia Kranias Lab at the University of Cincinnati. (reference.com)
  • Characterization of multiple [3H]ryanodine binding sites on the Ca2+ release channel of sarcoplasmic reticulum from skeletal and cardiac muscle: evidence for a sequential mechanism in ryanodine action. (aspetjournals.org)
  • Possible stimulation of Ca2+ release via a transverse tubule-sarcoplasmic reticulum mechanism. (rupress.org)
  • This triggers the opening of calcium channels, and the release of calcium from the sarcoplasmic reticulum into the cytoplasm of the cell. (sciencesource.com)
  • The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. (wikipedia.org)
  • The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). (wikipedia.org)
  • The sarcoplasmic reticulum (SR) of muscle cells is a specialized form of the endoplasmic reticulum (ER) dedicated to storage and release of Ca 2+ . (pnas.org)
  • Skeletal muscle contains an internal membrane system called the sarcoplasmic reticulum (SR) whose function is to regulate the Ca 2+ concentration of the myoplasm. (pdx.edu)
  • Half-maximum inhibition occurred at an Ca2+ concentration of about 0.8 .mu.M. The phosphoprotein steady-state level was reduced by 85-90% by phospholipase-A treatment or solubilization of Ca-preloaded sarcoplasmic reticulum with Triton X-100. (eurekamag.com)
  • Kinetic and equilibrium measurements of [3H]ryanodine binding to the Ca2+ release channel of rabbit skeletal and rat cardiac sarcoplasmic reticulum (SR) are examined to ascertain the nature of cooperative interactions among high and low affinity binding sites and to quantitate their distribution. (aspetjournals.org)