Chronic exercise training does not alter pulmonary vasorelaxation in normal pigs

Exercise training increases acetylcholine-induced pulmonary vasorelaxation in pigs with coronary occlusion. The present study tested the hypothesis th at chronic exercise training enhances endothelium-mediated vasorelaxation i n pulmonary arteries from normal pigs. Yucatan miniswine exercised for 16 w k on a treadmill (Ex); control pigs (Sed) remained in pens. Pulmonary arter y rings (2- to 3-mm OD) were studied using standard isometric techniques. C ontractile responses to 80 mM KCI and norepinephrine (NE) were determined. Vessels were constricted with levels of NE that resulted in half-maximal co ntraction to examine endothelium-dependent relaxation to ACh and endotheliu m-independent relaxation to sodium nitroprusside in the presence and absenc e of nitric oxide synthase inhibition, cyclooxygenase inhibition, and endot helial denudation. Arteries from Ex pigs developed increased contraction to 80 mM KCI, but the response to NE did not differ between groups. Endotheli um-dependent and endothelium-independent responses did not differ between S ed and Ex in the presence or absence of pharmacological inhibitors or denud ation. We conclude that chronic exercise training does not alter endotheliu m-dependent or endothelium-independent vasorelaxation responses of pulmonar y arteries from normal pigs.