Time Course Of Acute Exercise-induced Impairment Of Endothelial Dependent Vasorelaxation: 286 Board #107 May 31 11

Regular endurance exercise improves endothelium dependent vasorelaxation. However, the initial stress of acute exercise may impair vascular function prior to the beneficial adaptive response. PURPOSE: The purpose of this study is to examine the effects of acute exhaustive exercise on endothelial-dependent vascular function. METHODS: 7-9 mo old, male, Wistar rats were divided into four groups (n=6/group): sedentary (SED), 6h post-exercise (6h), 24h post-exercise, and 48h post-exercise. Exercise consisted of one bout of exhaustive treadmill exercise lasting between 30–40 min. Endothelium dependent vasorelaxation was assessed in ring segments of the aorta by constructing an acetycholine dose response curve (10−10-10−5 M) in a wire myograph. RESULTS: Maximal vasorelexation was impaired in 6h (70.1+5.2%) and 24h (76.2+4.4%) compared to SED (86.9+4.2%) and 48h (83.7+4.4%). EC50 for 6h (3.9e−7) was significantly (p<0.05) greater than SED (1.3e−7) and 48h (1.5e−7). CONCLUSIONS: These data suggest that acute, exhaustive treadmill exercise results in impaired endothelial dependent vasorelaxation up to 24h post-exercise and returns to sedentary levels within 48h.