Ultrastructural effects of hydrogen peroxide on the sarcolemma of rat heart.

Ultrastructural effects of hydrogen peroxide (H2O2) on the sarcolemma of the isolated rat heart were investigated with transmission electron microscopy combined with biochemical, enzyme histochemical, and freeze fracture techniques. Three hundred microM H2O2 were continuously administered to the Langendorff perfused isolated rat hearts. A significant amount of lipid peroxidation associated with depressed Na-K-ATPase activity was observed after 15 minutes of H2O2 perfusion (Group I), and consequently the cell membrane permeability was greatly increased. When 2.5 mM,N'-diphenyl-1,4-phenylenediamine (DPPD), a potent antioxidant, was added to the perfusate, the lipid peroxidation was totally inhibited (Group II). DPPD prevented an increase in the cell membrane permeability. However, Na-K-ATPase activity was not restored by DPPD. Decreased cytochemical staining of Na-K-ATPase was associated with an increase in cell membrane permeability. H2O2 appears to affect, not only lipids but also, intramembranous proteins embedded in the cell membrane. The combined effects of H2O2 on the membrane lipid and proteins result in the formation of membranous blebs.