Similar Effects of Exercise on Endothelium-Dependent Relaxation in Brachial and Femoral Arteries of Hypercholesterolemic Swine

Abstract

Previous studies, one in the brachial artery (BR) and another in the femoral (FEM) arteries of swine, suggest that endurance exercise training (EX) improves endothelium-dependent relaxation in BR arteries but not FEM arteries of hypercholesterolemic swine. Rigorous determination of whether EX produces heterogeneous effects on endothelium-dependent relaxation in BR and FEM arteries of hypercholesterolemic swine requires an experimental design which examines responses in both arteries of the same experimental animals. PURPOSE: To test the hypothesis that endurance exercise training of hypercholesterolemic swine differentially effects endothelium-dependent relaxation in the BR and FEM arteries. METHODS: Sixteen adult male pigs were fed a high fat (HF) diet for 20 weeks. Four weeks after initiation of diet, pigs were either exercise trained (EX) or remained sedentary (SD). This yielded two experimental groups: HFSD and HFEX. BR and FEM arteries were harvested from each experimental group. In vitro assessment of endothelium-dependent dilation was determined by administering increasing doses of bradykinin (BK; 10-11-10-6 M) to BR and FEM rings in the absence or presence of L-arginine methyl ester (L-NAME; 300μM), indomethacin (INDO; 5μM) or L-NAME+INDO. Endothelium-independent dilation was assessed by administering increasing doses of sodium nitroprusside (SNP; 10-10-10-4 M). RESULTS: The dose response curves for BK induced relaxation of BR and FEM arteries were similar. In addition, exercise training had a similar effect on BK induced relaxation in the BR and FEM arteries incubated in INDO. L-NAME treatment blunted BK induced relaxation more in the BR and FEM arteries of SD than EX pigs. Also, BK induced relaxation was significantly greater in both the BR (∼26%) and FEM (∼19%) arteries incubated in L-NAME+INDO of EX relative to SD pigs. Interestingly, exercise training also appeared to cause a significant decrease in SNP induced relaxation in both FEM and BR arteries. CONCLUSION: Contrary to our hypothesis, endurance exercise training has a similar effect on endothelium-dependent relaxation in the BR and FEM arteries of hypercholesterolemic Yucatan miniature swine. Supported by NIH grants: HL 52490, HL 083597