The subcellular localization of calcium ion in mammalian myocardium

Abstract

In order to detect the subcellular localization of calcium in heart muscle the treatment of myocardium with oxalate has been used. The results prove that in cardiac muscle cells in situ there are several distinct calcium storage sites: the mitochondria, the sarcoplasmic reticulum (terminal cisterns and longitudinal sarcotubules), the sarcolemmal membrane (including the intercalated discs) and the subsarcolemmal vesicles. Mitochondria are the main sites of calcium storage in the heart muscle. The functional implications of these findings in relation to excitation-contraction coupling are discussed. © 1971, JAPAN SOCIETY OF HISTOCHEMISTRY AND CYTOCHEMISTRY. All rights reserved.