Synchronous occurrence of spontaneous localized calcium release from the sarcoplasmic reticulum generates action potentials in rat cardiac ventricular myocytes at normal resting membrane potential

M. C. Capogrossi, S. R. Houser, A. Bahinski, E. G. Lakatta

Research output: Contribution to journalArticlepeer-review

Abstract

Under certain conditions, spontaneous release of Ca2+ from the sarcoplasmic reticulum occurs in resting mammalian myocardium. In single rat ventricular myocytes, such spontaneous Ca2+ release appears localized rather than homogeneous. When the increase in cytosolic Ca2+ is present in a single locus within a cell, it causes a small depolarization, which, at the normal resting potential, is subthreshold for generating an action potential. However, when spontaneous Ca2+ release occurs simultaneously at more than a single discrete locus, the resultant sarcolemmal depolarization is augmented to levels that can induce an action potential, even when this depolarization begins at the normal resting membrane potential. Thus, the synchronous occurrence of multifocal localized increases in cytosolic Ca2+ due to spontaneous Ca2+ release from the sarcoplasmic reticulum within ventricular myocytes is a mechanism for 'abnormal automaticity'.

Original languageEnglish (US)
Pages (from-to)498-503
Number of pages6
JournalCirculation research
Volume61
Issue number4
DOIs
StatePublished - 1987

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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