Membrane damage and the pathogenesis of cardiomyopathies.

Membrane damage plays an important role in the pathogenesis of ischemic damage to the myocardium, and is ultimately responsible for the release of cellular contents-notably intracellular enzymes-after ischemic cell death. This membrane damage may be caused by the incorporation of lipids into myocardial membranes, by the enzymatic actions of lipases that hydrolyze membrane phospholipids, and by free radicals that are produced in the ischemic myocardium. Much less is known of the role of membrane damage in the cardiomyopathies, but direct myocardial membrane damage may occur in some specific forms of this diverse class of diseases. Direct membrane effects of exogenous substances are likely to be of pathogenic significance in alcoholic and some toxic cardiomyopathies, for example those produced by hydrocarbons and adriamycin. Membrane damage may also play a role in the pathogenesis of viral cardiomyopathies, due possibly to incorporation of viral components into the cardiac sarcolemma where these foreign materials can serve as antigens that direct host responses to attack the cells of the heart.