The role of free radical-mediated processes in oxygen-related damage in cultured murine myocardial cells.

Abstract

A new approach to quantifying myocyte cell death utilizing fluorescence-activated sorting of antimyosin antibody-labeled cells was used to study the effects of oxygen-generated free radicals on cell survival. Uptake of antimyosin, reflecting sarcolemmal damage, increased under conditions which promoted elevated free radical formation and decreased in the presence of increased levels of free radical-scavenging agents. Superoxide dismutase decreased antimyosin uptake at pH 6.7 and 7.5. Mannitol decreased antimyosin uptake at pH 6.5 and 6.7 but not at pH 7.5, and dimethyl sulfoxide decreased antimyosin uptake at pH 6.4 but not at pH 7.5. These data suggest that a greater portion of hydroxyl radicals are produced at higher concentrations of hydrogen ion. Mannitol, a scavenger of hydroxyl radicals, was effective in reducing antimyosin uptake at pH 7.5 in the presence of ferrous sulfate, but had no effect on antimyosin uptake in the absence of ferrous sulfate, suggesting possible iron-mediated catalysis of hydroxyl radical formation. The data suggest that oxygen-derived free radicals can cause significant loss of membrane integrity in cultured myocytes, that the species of radical formed is dependent both on pH and the concentration of iron salts, and that this injury is, at least in part, preventable by the administration of exogenous radical scavenging agents.