Relation Between the Sarcolemmal Ca 2+ Current and Ca 2+ Sparks and Local Control Theories for Cardiac Excitation-Contraction Coupling - Archive ouverte HAL Access content directly
Journal Articles Circulation Research Year : 1996

Relation Between the Sarcolemmal Ca 2+ Current and Ca 2+ Sparks and Local Control Theories for Cardiac Excitation-Contraction Coupling

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Abstract

Ca2+ sparks, the elementary events underlying excitation-contraction (E-C) coupling, occur when sarcoplasmic reticulum (SR) Ca2+ release channels open. They are activated locally by Ca2+ influx through sarcolemmal (SL) Ca2+ channels. By measuring the probability of spark occurrence under conditions in which their probability of occurrence is low, we address two important questions raised by our recent work: (1) When a Ca2+ spark is triggered, how many SL Ca2+ channels (at a minimum) contribute to its activation? (2) What is the relation between the subcellular local [Ca2+], produced by the opening of SL Ca2+ channels and the consequent SR Ca2+ release? By comparing the voltage dependence of Ca2+ sparks in rat ventricular myocytes with the Ca2+ current, we show that the opening of a single SL Ca2+ channel can trigger a Ca2+ spark. Furthermore, we deduce that the probability of SR Ca2+ release depends of the square of the local [Ca2+]i produced by SL Ca2+ channel openings. These results are discussed with respect to the properties of Ca2+-induced Ca2+-release (CICR) and the local control theory of excitation-contraction coupling.
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inserm-02477359 , version 1 (13-02-2020)

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L.F. Santana, H. Cheng, Ana Maria Gómez, M.B. Cannell, W.J. Lederer. Relation Between the Sarcolemmal Ca 2+ Current and Ca 2+ Sparks and Local Control Theories for Cardiac Excitation-Contraction Coupling. Circulation Research, 1996, 78 (1), pp.166-171. ⟨10.1161/01.res.78.1.166⟩. ⟨inserm-02477359⟩

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