NITRIC OXIDE IN POST EXERCISE HYPOTENSION & VASODILATION

这项研究的长期目标是确定影响运动后低血压和血管扩张的因素。单次有氧运动(例如，在中等水平骑自行车1小时)可以长期降低血压，这就是所谓的“运动后低血压”。认为运动后低血压可能在耐力运动训练的降压效果中起一定作用。相反，过度的运动后低血压可能会导致运动后晕倒的有害倾向。因此，有必要进一步了解是什么导致了运动后低血压。目前尚不清楚内源性血管扩张剂一氧化氮是否参与了这一现象。这项研究的具体目标是确定一氧化氮在运动后低血压和血管扩张中的作用。该研究计划基于先前用于调查运动后低血压的随机交叉设计(Halliwill等人。生理学杂志495：279-288,1996)。在熟悉课程和体能测试之后，受试者将在两个不同的日子进行平行实验。实验的顺序将在Sham和运动之间随机进行，Sham是60分钟的坐位直立休息时间，而运动是以60%的峰值有氧功率进行60分钟的坐位直立骑行。这种强度和持续时间的运动会产生持续的(~2小时)运动后低血压(Halliwill等人)。我是J.Physiol。270：R420-R426,1996)。在假手术和运动后，受试者将依次接受全身α-肾上腺素能阻断(酚妥拉明)和一氧化氮合酶阻断(L-NMMA)。在这些干预前后，将测量全身和局部血流动力学。

The long-term goal of this research is to determine the factors that mediate post-exercise hypotension and vasodilation. A single bout of aerobic exercise (e.g., cycling for 1 hour at a moderate level) produces a long-lasting decrease in blood pressure, known as "post-exercise hypotension." It is believed that post-exercise hypotension may play a role in the beneficial anti-hypertensive effects of endurance exercise training. Conversely, exaggerated post-exercise hypotension may result in a detrimental tendency to faint after exercise. Thus, there is a need to further understand what mediates post-exercise hypotension. Currently it is unknown whether the endogenous vasodilator nitric oxide contributes to this phenomenon. The specific goal of this study is to determine the role of the nitric oxide in post-exercise hypotension and vasodilation. The study plan is based on a randomized crossover design used previously to investigate post-exercise hypotension (Halliwill et al. J Physiol Lond 495:279-288, 1996). After a familiarization session and fitness test, subjects will undergo parallel experiments on two separate days. The order of the experiments will be randomized between sham, a 60 min period of seated upright rest: and exercise, a 60 min period of seated upright cycling at 60% of their peak aerobic power. Exercise of this intensity and duration produces a sustained (~2 hr) post-exercise hypotension (Halliwill et al. Am J. Physiol. 270:R420-R426, 1996). Following both sham and exercise, subjects will receive, in sequence, systemic alpha-adrenergic blockade (phentolamine) and nitric oxide synthase blockade (L-NMMA). Before and after these interventions, systemic and regional hemodynamics will be measured.