Biomaterial Database

Ca(2+)-dependent negative control mechanism for Ca(2+)-induced Ca2+ release in crayfish muscle. 1994

S Györke, and P Palade

Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.

The mechanism of termination of Ca(2+)-induced Ca2+ release (CICR) from the sarcoplasmic reticulum has been investigated in voltage clamped cut crayfish muscle fibres loaded with rhod-2. During depolarizing steps evoking calcium current (ICa), Ca2+ release was first activated. Then the release rapidly (tau approximately 6 ms) declined, as evidenced by the rate of change of the intracellular fluorescence signal representing a Ca2+ transient. The rapid termination of release was not accounted for by inactivation of the trigger ICa or depletion of Ca2+ from the SR, since the rate at which release declined was constant under conditions where the rate of ICa inactivation and the amount of Ca2+ released varied widely. Pre-elevations of [Ca2+]i with prepulses or photolysis of caged Ca2+ caused depression of Ca2+ release during a subsequent test pulse. When the rate of ICa onset was varied by applying voltage ramps with different slopes, currents with fast onset elicited larger Ca2+ release than calcium currents with slower onset, even though the amplitude of the currents was the same. These results suggest that a Ca(2+)-dependent negative control mechanism exists which mediates the termination of CICR independently of the duration of the trigger ICa and before significant depletion of Ca2+ in the SR occurs.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009467	Neuromuscular Depolarizing Agents	Drugs that interrupt transmission at the skeletal neuromuscular junction by causing sustained depolarization of the motor end plate. These agents are primarily used as adjuvants in surgical anesthesia to cause skeletal muscle relaxation.	Depolarizing Muscle Relaxants,Muscle Relaxants, Depolarizing,Depolarizing Blockers,Agents, Neuromuscular Depolarizing,Blockers, Depolarizing,Depolarizing Agents, Neuromuscular,Relaxants, Depolarizing Muscle
D010782	Photolysis	Chemical bond cleavage reactions resulting from absorption of radiant energy.	Photodegradation
D002118	Calcium	A basic element found in nearly all 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.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D003400	Astacoidea	A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.	Astacus,Crayfish,Procambarus,Astacoideas,Crayfishs
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012519	Sarcoplasmic Reticulum	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.	Reticulum, Sarcoplasmic,Reticulums, Sarcoplasmic,Sarcoplasmic Reticulums
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In