EFFECT OF TRILINOLEIN ON SUPEROXIDE-DISMUTASE ACTIVITY AND LEFT-VENTRICULAR PRESSURE IN ISOLATED RAT HEARTS SUBJECTED TO HYPOXIA AND NORMOXIC PERFUSION

Oxygen-derived free radicals have been implicated in the development o f myocardial injury during hypoxia/reperfusion. Antioxidants can effec tively inhibit the formation of free radicals and ameliorate the myoca rdial damage which may occur during hypoxia/reperfusion, Trilinolein i s a triacylglycerol recently purified from the traditional Chinese med icinal plant Panax pseudo-ginseng. It has linoleic-acid residues as th e only type of fatty acid residue in all three esterified positions of the triacyglycerol. It has been proposed that decreased endogenous su peroxide dismutase (SOD) activity may contribute to free radical-media ted reperfusion injury of the ischemic myocardium. In the present stud y, when isolated rat hearts were subjected to hypoxia for 10, 30, 60 a nd 90 min without normoxic perfusion, a significant decrease in Mn-SOD activity was shown throughout the period of hypoxia, whereas the Cu Z n-SOD activity was increased at 10 and 30 min but was not different fr om the baseline at 60 and 90 min of hypoxia. In rat hearts pretreated with 10(-7) mol/l trilinolein and subjected to 60 min of hypoxia witho ut normoxic perfusion, Cu Zn-SOD was augmented compared with baseline and compared with hearts subjected to 60 min of hypoxia without trilin olein, whereas Mn-SOD activity was still reduced compared with baselin e, although less so than after 60 min of hypoxia without trilinolein. Pretreatment with trilinolein was associated with better preservation of left ventricular function during hypoxia and more rapid return to r ecovery during normoxic perfusion, This myocardial protective effect m ay be related to an antioxidant effect through potentiation of SOD, pa rticularly Cu.Zn-SOD during hypoxia.