Studies of sarcoplasmic reticulum function and contraction duration in young adult and aged rat myocardium

J. P. Froehlich, E. G. Lakatta, E. Beard, H. A. Spurgeon, M. L. Weisfeldt, G. Gerstenblith

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147 Scopus citations


Kinetic measurements of Ca+2 uptake in microsomal fractions from rat myocardium demonstrated significantly lower rates of oxalate-facilitated accumulation in preparations from aged (24 to 25 month) hearts as compared to those from young adult (6 to 8 month) hearts. The per cent decline in transport activity in microsomes from aged hearts varied with Ca2+ concentration decreasing from 57% at 0.33 μm Ca2+ to 24% at 1.21 μm Ca2+. Double-reciprocal plots of the dependence of the velocity of accumulation on Ca2+ concentration showed upward curvature in both age groups indicating the presence of multiple Ca2+ binding sites. Mechanical studies using muscles isolated from the same hearts used to prepare sarcoplasmic reticulum demonstrated prolonged contraction duration in aged myocardium in agreement with previous findings. The lower in vitro rates of Ca2+ accumulation in aged microsomes suggest a possible biochemical mechanism to account for the observed increase in the time-course of cardiac relaxation.

Original languageEnglish (US)
Pages (from-to)427-438
Number of pages12
JournalJournal of Molecular and Cellular Cardiology
Issue number5
StatePublished - May 1978


  • Aging
  • Ca uptake
  • Contraction duration
  • Rat myocardium
  • Sarcoplasmic reticulum

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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