Antioxidant changes in hypertrophied and failing guinea pig hearts

Hypertrophy and heart failure were induced by placing a mildly constrictive band around the ascending aorta in young guinea pigs. Based on heart weight, left ventricular wall thickness, hemodynamic data, and other clinical signs, these animals were found to have physiological hypertrophy at 10 wk and congestive heart failure (CHF) at 20 wk. Hearts from these two groups of animals were examined for superoxide dismutase (SOD), glutathione peroxidase (GSHPx), and catalase activities as well as lipid peroxidation and glutathione [reduced glutathione (GSH)/oxidized glutathione (GSSG)] levels. There was an age-dependent increase in SOD activity and GSH content in sham controls. SOD activity was 28% higher in the 10-wk-hypertrophy group and 46% lower in the CHF group than in respective sham controls. GSHPx activity increased significantly in the hypertrophied hearts, whereas in the failing hearts, the activity was not different from the 20-wk controls but was significantly lower than in the hypertrophied hearts. Catalase activity did not change at either stage. GSH content in the hypertrophied hearts was significantly higher compared with sham controls. In the CHF group, GSH content was significantly lower and GSSG content was significantly higher than in sham controls. Lipid peroxidation, as indicated by malondialdehyde content, was significantly decreased in the hypertrophy group but increased toward control levels in the failure group. It is proposed that a relative deficit in myocardial antioxidant capacity as well as in the redox state may play a role in the pathogenesis of cardiac failure.