Effect of trilinolein on superoxide dismutase activity in isolated rat cardiomyocytes subjected to hypoxia and normoxic perfusion

Background. Myocardial damage during ischemia/reperfusion has been linked to oxygen free radical production. Scavengers of oxygen free radicals can effectively ameliorate myocardial injury during ischemia/reperfusion. Decreased endogenous SOD activity may contribute to free-radical-mediated reperfusion injury of the ischemic myocardium. Trilinolein is a potent natural plant antioxidant recently purified from the traditional Chinese medicinal plant Panax pseudo-ginseng. It has linoleic-acid residues as the only type of fatty acid in all three esterified positions of the triacylglycerol. Methods and Results. The present data reveal that, when isolated rat cardiomyocytes were pretreated with 10^-8 M trilinolein, after oxygenarian with 100% O₂ for 5 min, the activities of Mn-SOD and Cu·Zn-SOD were potentiated. During hypoxia, in cardiomyocytes pretreated with 10-¹⁰ and 10^-8 M trilinolein, the activity of Mn-SOD was reduced but was still greater than the control levels without trilinolein, whereas the rise in Cu·Zn-SOD seen with control studies was alternated. During subsequent normoxia cardiomyocytes pretreated with trilinolein showed further decreases in Mn-SOD whereas the controls tended to rise. Cu·Zn-SOD levels were maintained compared with a fall in control studies. Conclusions. Since ischemia/reperfusion produce excessive amount of oxygen free radicals when compared to ischemia only, the preservation of Cu·Zn-SOD activity in isolated cardiomyocytes after pretreatment with trilinolein implies trilinolein is an effective free radical scavenger which could stabilize the levels of SOD during hypoxia and subsequent normoxia.