Actomyosin interaction modulates resting length of unstimulated cardiac ventricular cells

S. J. Sollott, B. D. Ziman, D. M. Warshaw, H. A. Spurgeon, Edward Lakatta

Research output: Contribution to journalArticlepeer-review

Abstract

We sought to determine whether resting or diastolic cardiac myocyte length during low stimulation rates is regulated by myofilament interaction. Cytosolic Ca2+ concentration ([Ca2+]i, via indo 1 fluorescence) and length, in the presence and absence of 2,3-butanedione monoxime (BDM), a potent inhibitor of force production in striated muscle, were measured in rat and guinea pig cardiac myocytes at rest and after electrical stimulation. In tetanized cells BDM reduced steady contraction amplitudes for a given [Ca2+]i. In an actomyosin-sliding filament assay without Ca2+ or regulatory proteins, BDM decreased actin filament velocity along myosin. BDM increased both diastolic and resting cell lengths without changes in [Ca2+]i. The resting cell length also increased when [Ca2+]i was reduced by removing extracellular Ca2+, an effect further enhanced by BDM and by loading cells with the intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid-acetoxymethylester. Thus myofilament interaction is present in cardiac cells, both at rest or during low rates of stimulation, and this myofilament interaction is regulated, in part, by the ambient [Ca2+]i.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume40
Issue number3
StatePublished - Sep 1996
Externally publishedYes

Keywords

  • Cardiac cells
  • Intracellular calcium concentration

ASJC Scopus subject areas

  • Physiology

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