UBIQUITIN AND HSP-72 EXPRESSION AND APOPTOSIS AFTER AN ACUTE BOUT OF ECCENTRIC EXERCSIE

Abstract

This study determined the effect of eccentric exercise on HSP-72 and ubiquitin mRNA and protein expression, HSF-1 and myofibrillar protein content, caspase-3 activity, and muscle strength and soreness. Nine males were randomly assigned to either an eccentric exercise (ECC) or control group (CON). ECC underwent one eccentric exercise bout involving 7 sets of 10 repetitions at 150% 1-RM of the dominant knee extensors. Blood samples were obtained and muscle strength and soreness assessed before and at 12, 24, and 48 hr post-exercise. Muscle biopsies were obtained 48 hr post-exercise. Data were analyzed with an independent groups t-test and correlations determined with the Pearson Correlation procedure (p < 0.05). Strength, soreness, and sTnI levels of ECC were significantly different from CON at 12, 24, and 48 hr post-exercise. The mRNA and protein levels of HSP-72, HSF-1, ubiquitin, caspase-3, and myofibrillar protein for ECC were all significantly different than CON. For ECC, significant correlations were located between HSP-72 mRNA and HSP-72 protein, ubiquitin mRNA and sTnI, and ubiquitin and myofibrillar protein and caspase-3 activity. These results indicate that a single bout of eccentric exercise up-regulates ubiquitin and HSP-72 expression along with increases in caspase-3 activity.