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Lack of direct role for calcium in ischemic diastolic dysfunction in isolated hearts

F R Eberli1, H Strömer, M A Ferrell

  • 1Cardiac Muscle Research Laboratory, Boston University School of Medicine, Boston, MA, USA.

Circulation
|November 22, 2000
PubMed

Insights

Ischemic diastolic dysfunction is not directly caused by changes in intracellular calcium levels. Experiments altering calcium availability during ischemia did not affect left ventricular diastolic pressure.

Area of Science:

  • Cardiovascular Physiology
  • Myocardial Ischemia Research
  • Calcium Signaling in Heart Muscle

Background:

  • Ischemia leads to increased intracellular calcium and diastolic dysfunction.
  • The direct role of myocyte calcium levels in ischemic diastolic dysfunction requires clarification.

Purpose of the Study:

  • To investigate if intracellular calcium levels directly determine diastolic dysfunction during ischemia.

Main Methods:

  • Isolated rat and rabbit hearts were subjected to low-flow ischemia.
  • Extracellular calcium levels were manipulated, and intracellular calcium was measured using aequorin.
  • Left ventricular pressures were monitored throughout the experiments.

Main Results:

  • Low-flow ischemia increased diastolic intracellular calcium by 270% and slowed calcium transient decline.
  • Experimental increases in extracellular calcium doubled intracellular calcium but did not worsen ischemic diastolic pressure.
  • Altering calcium availability during ischemia did not impact left ventricular diastolic pressure.

Conclusions:

  • Ischemic diastolic dysfunction is not directly mediated by calcium-activated tension.
  • Myocyte calcium levels may not be the primary driver of diastolic dysfunction during ischemia.
Abstract

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