Influence of antioxidants (mannitol and allopurinol) on oxygen free radical generation during and after cardiopulmonary bypass

ENGLAND, MICHAEL D. M.S.
CAVAROCCHI, NICHOLAS C. M.D.
O'BRIEN, JOHN F. PH.D.
SOLIS, EDUARDO M.D.
PLUTH, JAMES R. M.D.
ORSZULAK, THOMAS A. M.D.
KAYE, MICHAEL P. M.D.
SCHAFF, HARTZELL V. M.D.

Sections of Thoracic and Cardiovascular Surgery and Clinical Chemistry, Mayo Clinic and Mayo Foundation, Rochester, MN.

Address for correspondence: Hartzell V. Schaff, M. D. Mayo Clinic, 200 First St. SW, Rochester, MN 55905.

Circulation 74:p III-137, November 1986.

Oxygen-derived free radicals (02-, H20, OH-) are produced during oxidative metabolism, ischemia and reperfusion, and cardiopulmonary bypass (CPB). When oxygen free radical production exceeds scavenging capacity, peroxidation of structural lipids in cell membranes can occur with potentially injurious consequences. In this prospective study, 45 patients were evaluated to determine the effect of CPB on oxygen free radical generation. Twenty patients in group I were controls. Exogenous oxygen free radical antioxidants were administered before bypass to patients in group 11 (n = 15, mannitol) and group III (n - 10, allopurinol). In group I, plasma H2O, increased during extracorporeal circulation from 65 + 6.0 to 125 ± 12μM/ml (p < .001). At similar sampling intervals, plasma H202 levels were significantly lower in group II (p < .03) and group III (p < .05) when compared with those in group I. Red blood cell H202 did not change in group I or group II. White blood cell H202 levels decreased in group I (p < .04) and group II during CPB. (Intracellular concentrations of H20 were not obtained in group III patients.) We conclude that cytotoxic oxygen radicals are generated during CPB and that pretreatment with free radical antioxidants, mannitol or allopurinol, may minimize the free radicals available for lipid peroxidation of biomembranes.