Cellular calcium fluctuations in mammalian heart: Direct evidence from noise analysis of aequorin signals in Purkinje fibers

W. G. Wier, A. A. Kort, M. D. Stern, E. G. Lakatta, E. Marban

Research output: Contribution to journalArticlepeer-review

Abstract

Indirect evidence suggests that fluctuations, or oscillations, in the intracellular free calcium concentrations ([Ca2+](i)) can occur spontaneously in intact cardiac preparations, but such [Ca2+](i) fluctuations have never been demonstrated directly. We used the bioluminescent Ca2+-sensitive protein aequorin to detect fluctuations in the [Ca2+](i) in canine cardiac Purkinje fibers. Noise analysis of the aequorin luminescence reveals prominent peaks of power density at frequencies of 1-4 Hz; these peaks become larger and shift to higher frequencies as the [Ca2+](i) increases. Caffeine and ryanodine abolish the [Ca2+](i) fluctuations, suggesting that Ca2+ release and uptake by the sarcoplasmic reticulum generate these events. When [Ca2+](i) fluctuations are present, less tension is produced at any given level of mean aequorin luminescence. Thus, [Ca2+](i) fluctuations will undermine attempts to relate [Ca2+](i) and force in intact myocardium.

Original languageEnglish (US)
Pages (from-to)7367-7371
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume80
Issue number23 I
DOIs
StatePublished - 1983
Externally publishedYes

ASJC Scopus subject areas

  • General

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