Exercise training improves endothelium-mediated vasorelaxation after chronic coronary occlusion

Abstract

The present study evaluated combined effects of chronic coronary occlusion and exercise training on endothelial function. Gradual occlusion was produced by placement of an ameroid constrictor around the proximal left circumflex (LCX) coronary artery of female swine. Two months after placement of the ameroid, animals were restricted to their pens or exercise trained for 16 wk. Epicardial arteries (>500 microm ID) were isolated from the collateral-dependent LCX coronary artery distal to the occlusion and the nonoccluded left anterior descending (LAD) coronary artery. Bradykinin- and ADP-mediated relaxation of LCX and LAD coronary arteries was enhanced after exercise training. Inhibition of nitric oxide synthase with N(G)-nitro-L-arginine methyl ester decreased bradykinin- and ADP-mediated relaxation in LCX and LAD myocardial regions. Importantly, combined inhibition of effects of endothelium-derived hyperpolarizing factor with increased extracellular K(+) (20-30 mM) and nitric oxide synthase completely abolished coronary LAD and LCX relaxation to bradykinin. Our data indicate that exercise training improves endothelium-mediated relaxation of arteries isolated after chronic coronary artery occlusion, likely as a result of enhanced production of nitric oxide and endothelium-derived hyperpolarizing factor.

Endothelium-Mediated Relaxation of Porcine Collateral-Dependent Arterioles Is Improved by Exercise Training

“…Current results also provide support to a previous report of beneficial effects of training in conduit-sized coronary arteries distal to occlusion. 23 Furthermore, because NO exerts multiple beneficial vasodilator, antithrombotic, and antiadhesive properties, these findings have particular clinical relevance to known protective actions of exercise-based rehabilitation programs in human patients with coronary disease 19 -21 and an impact on recent reports of a beneficial role of physical activity in reducing the incidence of a second myocardial infarction in patients who survive a first infarction. 19 In vivo mechanisms whereby exercise training produces beneficial adaptations of coronary endothelium distal to a chronic coronary occlusion remain unclear.…”

Exercise Training Enhances Vasodilation Responses to Vascular Endothelial Growth Factor in Porcine Coronary Arterioles Exposed to Chronic Coronary Occlusion

“…Training efficacy was determined via comparison of skeletal muscle citrate synthase activities 11,12,22 and heart-to-body weight ratios between SED and EX animals. Samples of deltoid and triceps brachii were immediately frozen in liquid N 2 and stored at Ϫ70°C.…”

Six months of aerobic exercise does not improve microvascular function in type 2 diabetes mellitus

“…These include individuals with chronic heart failure [7,8] coronary artery occlusion [9], hypertension [10,11], ageing [12], impaired glucose tolerance [13], type 1 diabetes [14] and type 2 diabetes [15], thereby supporting a role for regular exercise as a useful therapy for the reversal of endothelial dysfunction and the subsequent reduction in cardiovascular risk in these populations.…”