Exercise training does not alter acetylcholine-induced responses in isolated pulmonary artery from rat

In chronic exercise-trained animals, acetylcholine (ACh)-stimulated endothelial nitric oxide (NO) release is enhanced in the systemic circulation. The purpose of the present study was to determine whether chronic exercise training also enhances NO-mediated relaxation in rat pulmonary artery. Sprague-Dawley rats were randomly divided into groups of exercise-trained and sedentary control rats, The exercise-trained rats ran on a motor-driven treadmill at 30 m.min(-1) up a 15 degrees incline 10-60 min.day(-1), 5 days per week for 10 weeks, and had less body weight, lower serum total cholesterol and triglyceride levels than sedentary rats, Contraction induced by potassium chloride and prostaglandin (PG)F-2 alpha were similar between isolated conduit pulmonary arterial rings from sedentary and exercise-trained rats. There were no differences between PGF(2 alpha)-precontracted rings from sedentary and exercise trained rats in both ACh and sodium nitroprusside-induced relaxations, The NO synthase inhibitor, nitro-L-arginine, suppressed ACh-induced relaxation in both sedentary and exercise-trained rats. These results suggested chronic exercise training did not alter the acetylcholine-induced endothelial NO production and release and the sensitivity of vascular smooth muscle cell to NO in isolated conduit pulmonary artery of rat.