Exercise modulates antioxidant enzyme gene expression in rat myocardium and liver

Our previous studies have shown that exercise caused changes in the tissue activities of the antioxidant enzymes glutathione peroxidase, superoxide di smutase, and catalase in spontaneously hypertensive (SH) and Wistar-Kyoto ( WKY) rats. To determine whether the changes observed were due to changes in mRNA levels of the enzymes, levels of tissue mRNA were determined by quant itative RNase protection assay. Comparisons of tissue enzyme activities and mRNA levels in sedentary and exercised animals showed that, in some cases (e.g., glutathione peroxidase in SH and WKY myocardium), parallel changes i n enzyme activity and mRNA levels occurred, whereas in other cases (e.g., c atalase in SH and WKY liver), nonparallel changes were found. Exercise of h ypertensive rats altered antioxidant enzyme mRNA levels to those seen in no rmotensive animals in some, but not all, cases. The results suggest that tr anscriptional control over changes in exercise-related antioxidant enzyme a ctivities is operative in some cases, although in other cases posttranscrip tional regulatory mechanisms may exist.