Johnson L R, Parker J L, Laughlin M H
Department of Veterinary Biomedical Sciences, University of Missouri, Columbia, Missouri 65211, USA.
J Appl Physiol (1985). 2000 Feb;88(2):443-51. doi: 10.1152/jappl.2000.88.2.443.
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 studied by using standard isometric techniques. Contractile responses to 80 mM KCl, isosmotic KCl (10-100 mM), and norepinephrine (10(-8) to 10(-4) 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 +/- 3.5%) than did those of Sed pigs (52.3 +/- 3.9%; P < 0.05). Endothelium-independent relaxation to sodium nitroprusside did not differ. Inhibition of nitric oxide synthase significantly decreased acetylcholine-induced relaxation, with greater inhibition in arteries from Ex pigs (P < 0.05). Inhibition of cyclooxygenase enhanced relaxation to acetylcholine in arteries from Sed pigs. We conclude that exercise training enhances endothelium-dependent (ACh-mediated) vasorelaxation in pulmonary arteries by mechanisms of increased reliance on nitric oxide and reduced production of a prostanoid constrictor.
我们假设运动训练会导致猪肺动脉中内皮依赖性血管舒张增强。从接受手术诱导冠状动脉闭塞（使用阿梅里德闭塞器）的雌性尤卡坦小型猪获取肺动脉环（外径2至3毫米）。进行16周的运动训练，并使用标准等长技术研究血管舒缩反应。久坐不动（Sed）和运动训练（Ex）的猪对80 mM氯化钾、等渗氯化钾（10 - 100 mM）和去甲肾上腺素（10(-8)至10(-4) M）的收缩反应没有差异。在去甲肾上腺素收缩后，评估对内皮依赖性和非内皮依赖性血管舒张剂的舒张情况。Ex组猪的肺动脉对乙酰胆碱的最大舒张程度（61.9 +/- 3.5%）高于Sed组猪（52.3 +/- 3.9%；P < 0.05）。对硝普钠的非内皮依赖性舒张没有差异。一氧化氮合酶的抑制显著降低了乙酰胆碱诱导的舒张，Ex组猪的动脉中抑制作用更强（P < 0.05）。环氧化酶的抑制增强了Sed组猪动脉对乙酰胆碱的舒张。我们得出结论，运动训练通过增加对一氧化氮的依赖和减少类前列腺素收缩剂的产生，增强了肺动脉中内皮依赖性（乙酰胆碱介导）的血管舒张。
