Superoxide generation during cardiopulmonary bypass: is there a role for vitamin E?

The cytotoxic metabolites of oxygen [superoxide (O-2), hydrogen peroxide (H2O2), and hydroxyl (OH.)] have been demonstrated to be involved in the peroxidation of membrane lipids consequently altering membrane composition, morphology, and function. Of all the lines of defense adopted by living organisms against toxic oxygen free radicals, vitamin E is most effective in the prevention of membrane damage. Cardiopulmonary bypass (CPB) has been shown to activate complement and cause sequestration of leukocytes which can recruit, adhere, and stimulate release of cytotoxic oxygen radicals. A prospective study of 30 patients evaluated the effects of CPB with and without an exogenous free radical scavenger (Group I, N = 20, control) and (Group II, N = 10, vitamin E) on H2O2 (a marker of oxygen free radicals) malonaldehyde (a marker of lipid peroxidation), transpulmonary leukosequestration, and plasma levels of vitamins E and C. Group I showed a progressive increase in H2O2 during CPB from 65 +/- 6 to 130 +/- 11 micron/ml (P less than 0.0001); plasma vitamin E decreased from 15 +/- 3 to 6 +/- 1 mg/liter (P less than 0.0001) while vitamin C increased from 1.6 +/- .3 to 2.3 +/- .3 mg/dl (P less than 0.0001). Group II showed no significant increase in H2O2 (from 78 +/- 8 to 93 +/- 5 microns/ml) during CPB and a significant reduction in H2O2 levels compared to Group I (P less than 0.001); plasma vitamins E and C did not change significantly in Group II.(ABSTRACT TRUNCATED AT 250 WORDS)