A significant change in cell morphology was observed in hepatocytes treated with t-butyl hydroperoxide (t-BH). This morphological change of multiple bleb formation on cell plasma membranes was related to cell damage, and the subsequent rupture of these blebs resulted in cell death. In cells incubated with .alpha.-tocopherol before t-BH treatment, bleb formation was significantly inhibited. Using fluorescence microscopy, actin organization was shown to be related to .alpha.-tocopherol status as demonstrated by early changes in the actin network of cells in the absence of .alpha.-tocopherol. Results from SDS-polyacrylamide gel electrophoresis further indicated that, under oxidative stress, actin molecules (45kDa) decreased in amount and were accompanied by the formation of high molecular weight molecules. In the presence of the thiol reducing agent, dithiothreitol, both the decrease in monomeric actin and formation of high molecular weight molecules disappeared. The loss of actin showed a time-dependent response and could be observed after 15 min with t-BH treatment either in the presence or absence of .alpha.-tocopherol; however the extent was much more significant in cells with no .alpha.-tocopherol. Depletion of total membrane protein thiols was also related to vitamin E and greater in cells with no .alpha.-tocopherol. The amount of cell damage, as determined by lactate dehydrogenase (LDH) leakage in cells with t-BH treatment over 120 min was decreased in the presence of .alpha.-tocopherol compared with the rapid increase of LDH leakage in the absence of .alpha.-tocopherol. These results indicate that vitamin E protection of cell morphology under oxidative stress is related to actin, with thiol groups in actin probably playing a key role.
