Role of inositol 1,4,5-trisphosphate in excitation-contraction coupling in skeletal muscle.
The sarcoplasmic reticulum (SR) of skeletal muscle is an intracellular membranous network that controls the myoplasmic Ca2+ concentration and the contraction-relaxation cycle. Ca2+ release from the terminal cisternae (TC) region of the SR evokes contraction. How electrical depolarization of the transverse tubule is linked to Ca2+ release from the junctionally associated TC is still largely unknown. Independent evidence has been recently obtained indicating that either inositol trisphosphate (IP3) or (and) Ca2+ is (are) the chemical transmitter(s) of excitation-contraction coupling. Here we outline the experimental data in support of each transmitter and discuss possible interactive roles of Ca2+ and IP3.
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Volpe
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Di Virgilio
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Pozzan
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Salviati
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000502:physiology; D013403:Sugar Phosphates / Q000502:physiology*
D007295:Inositol Phosphates; D007473:Ion Channels; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D019204:GTP-Binding Proteins; D011188:Potassium; D002118:Calcium