急性缺氧暴露情况下运动对中动脉脑血流速度的影响

Effect of Exercise in Acute Hypoxic Exposure on Velocity of Middle Cerebral Blood Flow

利用常压低氧屋模拟2500m高原急性缺氧,测试了6名世居平原的男子在常氧和急性缺氧情况下,中等强度运动前后中动脉经颅多普勒血流速度的变化。结果显示,急性缺氧暴露情况下,安静时平均脑血流速度(Vm)、收缩期血流速度(Vp)和舒张期血流速度(Vd)从第5min到第20min都持续上升,且Vd增加幅度最大。常氧和急性缺氧运动后即刻,Vm和Vp均显著增加,常氧运动后Vm、Vp的增加幅度均高于急性缺氧运动后;常氧运动后Vd增加,而急性缺氧运动后Vd略有降低。提示,急性缺氧主要通过调节脑血管阻力增加舒张期血流速度,从而增加脑血流量来满足动脉氧含量下降时大脑的供氧需求;急性缺氧运动与常氧运动一样,都是通过增加收缩期血流速度来满足大脑供氧需求,但急性缺氧暴露抑制了运动对脑血流速度的增加效应;与常氧运动、急性缺氧相比,急性缺氧运动对舒张期血流速度的影响比对平均脑血流速度和收缩期血流速度的影响要大。

The velocity of middle cerebral blood flow of six sea level native males was measured before and after moderate constant exercise on normoxia and acute hypoxia using normobaric hypoxic house to simulate the acute hypoxia at altitude of 2 500m. The result showed that the rest mean velocity, peak velocity and End diastolic velocity rose continuously from the 5^th minute to 20^th minute on acute exposure and increment of peak velocity was the most. Mean velocity and peak velocity increased obviously instantly after exercise not only on normoxia but also on acute hypoxia. End diastolic velocity increased after exercise on normoxia but decreased slightly on acute hypoxia. It suggested that oxygen supply meeting the need for brain was mainly provided with the argument of cerebral flow through increasing of velocity of CBF. The need of oxygen supply for brain was provided by peak velocity of CBF in exercise on acute hypoxia and normoxia, Acute hypoxia restrained the effect of increasing of velocity CBF induced by exercise.