EXERCISE TRAINING IMPROVES VASODILATORY RESPONSE IN COLLATERAL ARTERY

Abstract

Exercise training increses collateral dependent blood flow in rats with femoral artery occlusion. The perforating artery, a branch of the distal femoral artery, functions as a collateral vessel following femoral artery occlusion. PURPOSE: Test the hypothesis that exercise training improves endothelium-dependent vasodilator responses of perforating arteries. METHODS: Male Sprague Dawley rats (∼320 g) were divided into Control (no occlusion, n = 5), or received unilateral occlusion (left) of the femoral artery and kept Sedentary (SEd; cage activity, n = 13), or Trained (Tr; ran at 20 m/min, 15% grade, twice/d, for 3 wk, n = 13). The perforating arteries from both hindlimbs were isolated and mounted on micropipettes with 45 cm H2O intraluminal pressure. Dilations in response to acetylcholine (Ach) and sodium nitroprusside (SNP; nitric oxide donor) (10−9 to 10−5M) were recorded with an inverted microscope. RESULTS: Training increased citrate synthase activity in both the occluded (∼46%) and non-occluded (∼21%) white gastroc. muscle (P < 0.005). In both Sed and Tr animals the perforating arteries from occluded side showed a greater vasodilation to Ach than arteries from the non-occluded hindlimbs (p < 0.005). The vasodilation responses in the non-occluded hindlimb were similar among groups. The isolated arteries from trained animals showed better recovery of SNP-induced vasodilation than Sed animals (p < 0.05). Occlusion increased maximal vessel diameter (from ∼320 μ, p < 0.001) similarly in both Sed (18 ± 0.05%) and Tr rats (21 ± 0.04%). CONCLUSION: Endothelial-dependent dilation response is enhanced following femoral artery occlusion, while training improves endothelial-independent dilation response in the perforating arteries. Supported by NIH grant HL38387 and HL 36088.