Anoxic injury of adult cardiac myocytes

Cultured adult cardiocytes were exposed to anoxia. The initial decrease of high-energy phosphates was accompanied by a moderate release of cytosolic enzymes and morphological changes: the appearance of sarcolemmal 'microblebs' (approximately 1 micron in diameter) and an increase of subsarcolemmal vesicles. At ATP levels above 2 mumol/gww, metabolic and morphological alterations were reversible. Probably the sarcolemmal changes are causally related to the loss of macromolecules from reversibly injured cells. At ATP levels below 2 mumol/gww, an increasing number of cells become irreversibly hypercontracted. In these cells cytoplasmic masses are protruded into large 'macroblebs' (10-30 micron in diameter), however sarcolemmal continuity is preserved. Thus, enzyme release, irreversible contracture and cytolysis do not occur simultaneously in anoxic isolated cardiocytes.