Lykidis Christos K, White Michael J, Balanos George M
School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Exp Physiol. 2008 Feb;93(2):247-53. doi: 10.1113/expphysiol.2007.09487.
The pulmonary circulation is influenced by the autonomic nervous system, yet whether this is physiologically important during exercise in man is not known. The aim of this study was to assess the pulmonary vascular response to sympathoexcitation induced by the maintained activation of the muscle metaboreflex in the postexercise period. Nine healthy subjects performed isometric handgrip exercise at 50% of their maximal voluntary contraction force for 2 min. Exercise was followed by circulatory occlusion so as to maintain the muscle metaboreflex activated for 2 min (postexercise circulatory occlusion; PECO). Blood pressure measurements and echocardiographically determined estimates of systolic pulmonary artery pressure (SPAP) and cardiac output were obtained at various intervals throughout the two protocols. Compared with baseline values, elevations in SPAP (by 20.06 +/- 2.08%), cardiac output (by 36.04 +/- 4.97%) and mean arterial pressure (MAP; by 25.62 +/- 3.54%) were noted during isometric exercise (means +/- s.e.m., all P < 0.05). Increases in SPAP and MAP persisted during PECO (all P < 0.05), whereas cardiac output returned to resting levels. Our findings suggest that the sympathoexcitation induced by isometric exercise affects the pulmonary circulation, possibly by inducing vasoconstriction and/or stiffening the large conduit arteries. The exaggerated activation of the sympathetic nervous system that has been evidenced in cardiopulmonary patients could therefore be implicated in their abnormal pulmonary haemodynamic responses and intolerance of exercise.
肺循环受自主神经系统影响，但在人类运动过程中这在生理上是否重要尚不清楚。本研究的目的是评估运动后时期肌肉代谢反射持续激活所诱发的交感神经兴奋对肺血管的反应。9名健康受试者以其最大自主收缩力的50%进行等长握力运动2分钟。运动后进行循环阻断，以使肌肉代谢反射持续激活2分钟（运动后循环阻断；PECO）。在整个两个方案的不同时间间隔测量血压，并通过超声心动图测定收缩期肺动脉压（SPAP）和心输出量的估计值。与基线值相比，等长运动期间SPAP升高（20.06±2.08%）、心输出量升高（36.04±4.97%）和平均动脉压（MAP；25.62±3.54%）（均值±标准误，均P<0.05）。在PECO期间，SPAP和MAP持续升高（均P<0.05），而心输出量恢复到静息水平。我们的研究结果表明，等长运动诱发的交感神经兴奋可能通过诱导血管收缩和/或使大的输送动脉变硬来影响肺循环。因此，心肺疾病患者中已证实的交感神经系统过度激活可能与他们异常的肺血流动力学反应和运动不耐受有关。
