Excitation-contraction coupling in heart IX. Changes in the intracellular stores of calcium in failing hearts due to lack of substrate and oxygen

Abstract

The levels of calcium in mitochondrial and microsomal fractions decreased in isolated rat hearts which failed to generate contractile force on perfusion with aerobic substratefree medium for 2 hr. Similar changes in the contents of calcium in the subcellular fractions of the hearts, in which contractility decreased by 80% of the control, were noted on perfusion for 30 min with hypoxic medium. These results reveal the importance of exogenous substrate and oxygen for the maintenance of the intracellular stores of the heart.