Transsarcolemmal calcium movements in arterially perfused rabbit right ventricle measured with extracellular calcium-sensitive dyes

D. W. Hilgemann, G. A. Langer

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Activation-dependent changes of mean extracellular calcium concentrations were monitored spectrophotometrically in arterially perfused right ventricle of rabbit via extracellular application of the calcium-sensitive absorption dyes, antipyrylazo III and tetramethylmurexide. After rest periods of 3 minutes or longer, 10% of total dye-accessible calcium (300-500 μM) is depleted cumulatively from the extracellular space by four to eight beats at 2 Hz stimulation. During continued stimulation, or during quiescence following a depletion response, mean extracellular calcium concentrations return toward the prestimulatory level in the course of 2-4 minutes. A single stimulation placed 2-30 seconds subsequent to rapid pacing results in a potentiated beat with an accompanying net increment of mean extracellular calcium. Total dye-accessible calcium can increase by at least 4% at such a beat, and depletion responses can be repeated immediately thereafter. During a sequence of such responses, extracellular calcium lost cumulatively during three to five rapid beats is replenished, for the most part, by a single post-stimulatory beat. These results demonstrate that most of the 'activator pool' of cellular calcium can turn over to the extracellular space during a single contraction cycle in rabbit myocardium, and suggest that, in mammalian myocardium, diastolic calcium efflux may be quantitatively negligible in relation to efflux during excitation-contraction coupling.

Original languageEnglish (US)
Pages (from-to)461-467
Number of pages7
JournalCirculation research
Volume54
Issue number4
DOIs
StatePublished - Jan 1 1984

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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