Chronic exercise training improves ACh-induced vasorelaxation in pulmonary arteries of pigs
Journal of applied physiology
Laughlin. Chronic exercise training improves ACh-induced vasorelaxation in pulmonary arteries of pigs. J. Appl. Physiol. 88: 443-451, 2000.-We hypothesized that exercise training would lead to enhanced endothelium-dependent vasodilation in porcine pulmonary arteries. Pulmonary artery rings (2-to 3-mm OD) were obtained from female Yucatan miniature swine with surgically induced coronary artery occlusion (ameroid occluder). Exercise training was performed for 16 wk, and vasomotor responses were
... or responses were studied by using standard isometric techniques. Contractile responses to 80 mM KCl, isosmotic KCl (10-100 mM), and norepinephrine (10 Ϫ8 to 10 Ϫ4 M) did not differ between sedentary (Sed) and exercise-trained (Ex) pigs. Relaxation was assessed to endothelium-dependent and endothelium-independent vasodilators after norepinephrine contraction. Pulmonary arteries of Ex pigs exhibited greater maximal relaxation to ACh (61.9 Ϯ 3.5%) than did those of Sed pigs (52.3 Ϯ 3.9%; P Ͻ 0.05). Endothelium-independent relaxation to sodium nitroprusside did not differ. Inhibition of nitric oxide synthase significantly decreased acetylcholineinduced relaxation, with greater inhibition in arteries from Ex pigs (P Ͻ 0.05). Inhibition of cyclooxygenase enhanced relaxation to acetylcholine in arteries from Sed pigs. We conclude that exercise training enhances endotheliumdependent (ACh-mediated) vasorelaxation in pulmonary arteries by mechanisms of increased reliance on nitric oxide and reduced production of a prostanoid constrictor. nitric oxide synthase; prostanoids; endothelium dependent; porcine; pulmonary circulation Original submission in response to a special call for papers on "Molecular and Cellular Basis of Exercise Adaptations." The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.