SUPEROXIDE-DISMUTASE AND CATALASE IN PROTECTION OF CARDIOPULMONARY BYPASS-INDUCED CARDIAC DYSFUNCTION AND CELLULAR INJURY

BACKGROUND: Cardiac dysfunction following cardiopulmonary bypass (CPB) is well known. Various possible sources for increased levels of oxyge n free radicals (OFRs) exist during CPB and OFRs depress cardiac funct ion. Postpump (following CPB) cardiac dysfunction may be due to increa sed levels of OFRs. METHODS: This study investigated the effects of co ld crystalloid cardioplegia with and without superoxide dismutase (SOD ) and catalase (CAT) on cardiac function (cardiac index [CI], left ven tricular work index [LVWI]), cardiac contractility (+dp/dt, +dp/dt/PAW [pulmonary arterial wedge pressure], +dp/dt/LVEDP [left ventricular e nd-diastolic pressure]), diastolic compliance (-dp/dt), OFR-producing activity of polymorphonuclear leukocytes (PMNL-CL); creatine kinase (C K) and MB isoenzyme of CK (MBCK), malondialdehyde (MDA), and white blo od cells (WBC) and PMNLs from coronary sinus blood; and lactate levels in arterial blood in anesthetized dogs at various times (up to 90 min s) of reperfusion following 90 mins of hypothermic ischemic cardiac ar rest. The dogs were divided into three groups: group I, sham bypass; g roup II, cold crystalloid cardioplegic cardiac arrest; group III, simi lar to group II but received SOD and catalase treatment. RESULTS: Post pump decreases in cardiac function, contractility and diastolic compli ance were associated with increases in PMNL-CL activity, blood MDA, pl asma CK and MBCK, and plasma lactate, and decreases in WBC and PMNLs. Prevention of post pump cardiac dysfunction (function and contractilit y) by SOD and CAT was associated with restoration in PMNL-CL activity, plasma CK and MBCK activity, and blood MDA towards control values alt hough not complete. The levels of plasma lactate, total WBC and PMNLs were similar in group II and group III. CONCLUSIONS: These results sug gest that postpump depression of cardiac function and contractility co uld be due to increased levels of OFRs and that SOD and CAT scavengers of superoxide anion and hydrogen peroxide respectively may be effecti ve in preventing postpump cardiac dysfunction.