Sarcoplasmic reticulum function in skinned fibers of hypertrophied rat ventricle

S. Kimura, A. L. Bassett, K. Saida, M. Shimizu, R. J. Myerburg

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27 Scopus citations

Abstract

This study was designed to examine the Ca2+ sensitivity of the contractile system and the ability of the sarcoplasmic reticulum (SR) to accumulate and release Ca2+ in chemically (saponin) skinned cardiac fibers obtained from normal and pressure-overloaded hypertrophied rat left ventricles. Left ventricular pressure overload was induced by partial ligation of the abdominal aorta 6-8 wk before study. Age- and weight-matched normal rats served as controls. Pressure overload increased the left ventricular weight-to-body weight ratio by 51%. There were no differences in the Ca2+-tension relationship between normal and hypertrophied preparations at Ca2+ concentrations of 10-7 to 10-4 M. Caffeine-induced Ca2+ release from the maximally Ca2+-loaded SR was also not different between the two groups at caffeine concentrations of 0.5-30 mM. However, when the relative amount of Ca2+ accumulated in the SR with 10-6, 3 x 10-6, or 10-5 M Ca2+ loading solutions for various loading periods was estimated by the area under the 25 mM caffeine-induced contraction, the accumulation of Ca2+ was significantly slower in hypertrophied fibers than in normal fibers. We conclude that depressed Ca2+ contractile performance in this model of chronic pressure overload in rats.

Original languageEnglish (US)
Pages (from-to)25/4
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume256
Issue number4
StatePublished - 1989

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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