Training induces nonuniform increases in eNOS content along the coronary arterial tree

1 Departments of Veterinary Biomedical Sciences and Medical Physiology, and Dalton Cardiovascular Research Center, University of Missouri Columbia, Missouri 65211; and 2 Vascular Biology Center, Medical College of Georgia, Augusta, Georgia 30912 Exercise training produces enhanced nitric oxide (NO)-dependent, endothelium-mediated vasodilator responses of porcine coronary arterioles but not conduit coronary arteries. The purpose of this study was to test the hypothesis that exercise training increases the amount of endothelial NO synthase (eNOS) in the coronary arterial microcirculation but not in the conduit coronary arteries. Miniature swine were either exercise trained or remained sedentary for 16-20 wk. Exercise-trained pigs exhibited increased skeletal muscle oxidative capacity, exercise tolerance, and heart weight-to-body weight ratios. Content of eNOS protein was determined with immunoblot analysis in conduit coronary arteries (2- to 3-mm ID), small arteries (301- to 1,000-µm ID), resistance arteries (151- to 300-µm ID), and three sizes of coronary arterioles [large (101- to 150-µm ID), intermediate (51- to 100-µm ID), and small (