Relation between the Sarcolemmal Ca2+ Current and Ca2+ Sparks and Local Control Theories for Cardiac Excitation-Contraction Coupling

Luis Fernando Santana, H. Cheng, A. M. Gómez, M. B. Cannell, W. J. Lederer

Research output: Contribution to journalArticle

208 Scopus citations

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+]i 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.

Original languageEnglish (US)
Pages (from-to)166-171
Number of pages6
JournalCirculation Research
Volume78
Issue number1
StatePublished - Jan 1996
Externally publishedYes

Keywords

  • Ca current
  • Excitation-contraction coupling
  • Fluo 3
  • Intracellular Ca
  • Nifedipine

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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