Heat stress redistributes blood flow in arteries of the brain during dynamic exercise
Heat stress redistributes blood flow in arteries of the brain during dynamic exercise
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动态运动期间热应激会重新分配大脑动脉中的血流
DOI：
10.1152/japplphysiol.00353.2015
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Ogoh S.
中科院分区：
文献类型：
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作者：
Sato K;Oue A;Yoneya M;Sadamoto T;Ogoh S.
我们假设热应激会减少运动时的大脑前后部血流量(CBF)，而前部CBF的减少可能与颅外血流量(BF)的大幅增加有关。9名受试者在高温(35°C；高温)和中温环境(25°C；对照)中，以峰值摄氧量的60%进行40min的半卧位循环。我们用超声检测颈外动脉(ECA)、颈内动脉(ICA)和椎动脉(VA)的BF和电导(Cond)。在高温状态下，ICA和VA BF在运动开始后10min显著升高(P<；0.05)，此后逐渐下降。ICA Cond显著降低(P<；0.05)，而VA Cond无明显变化。与对照组相比，热末ICA和VA的BF或COND有降低趋势，但差异不显著。相反，热末ECA、BF和COND均高于对照组水平(P<；0.01)。在高温期间，ICA BF的减少似乎与呼气末二氧化碳分压的下降有关(r=0.84)，而VA BF似乎受到心输出量变化的影响(r=0.87)。此外，高温期间ECABF的变化与ICA BF的变化呈负相关(r=−0.75)。热应激导致头部和脑动脉对运动的血管反应改变，从而改变心输出量的分布。此外，高温引起的颅外血流量增加可能会损害热应激运动时的前部脑血流量。
We hypothesized that heat stress would decrease anterior and posterior cerebral blood flow (CBF) during exercise, and the reduction in anterior CBF would be partly associated with large increase in extracranial blood flow (BF). Nine subjects performed 40 min of semirecumbent cycling at 60% of the peak oxygen uptake in hot (35°C; Heat) and thermoneutral environments (25°C; Control). We evaluated BF and conductance (COND) in the external carotid artery (ECA), internal carotid artery (ICA), and vertebral artery (VA) using ultrasonography. During the Heat condition, ICA and VA BF were significantly increased 10 min after the start of exercise (P< 0.05) and thereafter gradually decreased. ICA COND was significantly decreased (P< 0.05), whereas VA COND remained unchanged throughout Heat. Compared with the Control, either BF or COND of ICA and VA at the end of Heat tended to be lower, but not significantly. In contrast, ECA BF and COND at the end of Heat were both higher than levels in the Control condition (P< 0.01). During Heat, a reduction in ICA BF appears to be associated with a decline in end-tidal CO2tension (r= 0.84), whereas VA BF appears to be affected by a change in cardiac output (r= 0.87). In addition, a change in ECA BF during Heat was negatively correlated with a change in ICA BF (r= −0.75). Heat stress resulted in modification of the vascular response of head and brain arteries to exercise, which resulted in an alteration in the distribution of cardiac output. Moreover, a hyperthermia-induced increase in extracranial BF might compromise anterior CBF during exercise with heat stress.