RESUMEN
Physical activity has been shown to enhance endothelial function of central and peripheral vascular beds. The primary purpose of the present study was to test the hypothesis that a short-term exercise training program would result in enhanced endothelium-dependent vasorelaxation of a major artery supplying blood flow to the knee joint, the middle genicular artery. Female Yucatan miniature swine were randomly assigned into exercise trained (n=7) or sedentary (n=7) groups. Exercise trained pigs underwent a daily exercise training program on treadmills for 7 days. In vitro assessment of vasorelaxation was determined in a dose response manner by administrating increasing doses of 3 different dilators; adenosine diphosphate, bradykinin, and sodium nitroprusside. The role of nitric oxide synthase and cyclooxygenase pathways in vasomotor responses was evaluated with specific inhibitors using nitro-L-arginine methyl ester and indomethacin incubation, respectively. The results of this investigation indicate that adenosine and bradykinin-induced endothelium-dependent vasorelaxation were significantly enhanced in middle genicular artery from exercise trained pigs (p<0.05). Endothelium-independent vasorelaxation was not altered with exercise training as determined by the response to sodium nitroprusside. The findings of the present investigation indicate that short-term exercise training enhances endothelial function of middle genicular artery through adaptations in the nitric oxide synthase and by non-nitric oxide synthase, non-cyclooxygenase pathways.