Alterations in the calcium homeostasis of skeletal muscle from postmyocardial infarcted rats

Gyula Péter Szigeti, János Almássy, Mónika Sztretye, Beatrix Dienes, László Szabó, Péter Szentesi, Guy Vassort, Sándor Sárközi, László Csernoch, István Jóna

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

In chronic heart failure, skeletal muscles develop a weakness that is not associated to an impaired circulatory function but rather to alterations in the skeletal muscle fibers themselves. To understand these changes, the steps in excitation-contraction coupling of rats that underwent a left anterior coronary artery occlusion were studied. About 24 weeks after the myocardial infarction, neither the total amount nor the voltage dependence of intramembrane charge were altered. In contrast, calcium release from the sarcoplasmic reticulum was considerably suppressed, and its voltage dependence shifted toward more positive voltages. Elementary calcium-release events showed altered morphology as the relative proportion of embers increased. Calcium sparks were smaller in amplitude and had larger time-to-peak values. Isolated ryanodine receptors (RyR) displayed an unusual rectification with increased single-channel conductance at positive (cis vs trans) voltages. In addition, the bell-shaped calcium dependence of channel activity was broader, with a slight shift of activation to lower and a larger shift in inactivation to higher calcium concentrations. These data indicate that the number of channels that open during a calcium-release event is decreased and that RyR function is altered; thus, calcium-release is suppressed after a myocardial infarction. These observations give an explanation for the impaired skeletal muscle function in these animals.

Original languageEnglish
Pages (from-to)541-553
Number of pages13
JournalPflugers Archiv European Journal of Physiology
Volume455
Issue number3
DOIs
Publication statusPublished - Dec 2007

Keywords

  • Calcium sparks
  • Calcium transients
  • Charge movement
  • Myocardial infarction
  • Ryanodine receptor
  • Single channel

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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