Huang S Y, Sun S, Droma T, Zhuang J, Tao J X, McCullough R G, McCullough R E, Micco A J, Reeves J T, Moore L G
Shanghai Institute of Physiology, China.
J Appl Physiol (1985). 1992 Dec;73(6):2638-42. doi: 10.1152/jappl.1992.73.6.2638.
Cerebral blood flow increases with acute exposure to high altitude, but the effect of hypoxia on the cerebral circulation at rest and during exercise appears influenced by the duration of high-altitude exposure. To determine whether internal carotid artery flow velocity increased with exercise in long-term residents of high altitude and whether resting values and the response to exercise differed in lifelong vs. acclimatized newcomer male residents of high altitude, we studied 15 native Tibetan and 11 Han ("Chinese") 6 +/- 2-yr residents of Lhasa (3,658 m), Tibet Autonomous Region, China. Noninvasive Doppler ultrasound was used to measure internal carotid artery diameter, mean flow velocity, and, in combination, hemoglobin and arterial O2 saturation to assess cerebral O2 delivery. Tibetan and Han groups were similar in body size and resting internal carotid artery diameter, blood pressure, hemoglobin concentration, internal carotid artery mean flow velocity, and calculated cerebral O2 delivery. Submaximal exercise increased internal carotid artery mean flow velocity and cerebral O2 delivery in the Tibetan and Han subjects. At peak exercise, the Tibetans sustained the increase in flow velocity and cerebral O2 delivery, whereas the Hans did not. Across all exercise levels up to and including peak effort, the Tibetans demonstrated a greater increase in internal carotid artery flow velocity and cerebral O2 delivery relative to resting values than did the Hans. The greater cerebral O2 delivery was accompanied by increased peak exercise capacity in the Tibetan compared with the Han group. Our findings suggest that the cerebral blood flow response to exercise is maintained in Tibetan lifelong residents of high altitude.
急性暴露于高海拔地区时脑血流量会增加，但静息和运动时缺氧对脑循环的影响似乎受高海拔暴露持续时间的影响。为了确定长期居住在高海拔地区的人群运动时颈内动脉血流速度是否增加，以及高海拔地区终身居住的男性居民与适应环境的新迁入男性居民的静息值和运动反应是否存在差异，我们研究了15名藏族原住民和11名汉族（“中国”）男性居民，他们均为6±2岁，居住在中国西藏自治区拉萨市（海拔3658米）。使用无创多普勒超声测量颈内动脉直径、平均血流速度，并结合血红蛋白和动脉血氧饱和度来评估脑氧输送。藏族和汉族组在体型、静息颈内动脉直径、血压、血红蛋白浓度、颈内动脉平均血流速度和计算得出的脑氧输送方面相似。次最大运动增加了藏族和汉族受试者的颈内动脉平均血流速度和脑氧输送。在运动峰值时，藏族人维持了血流速度和脑氧输送的增加，而汉族人则没有。在包括运动峰值在内的所有运动水平上，相对于静息值，藏族人颈内动脉血流速度和脑氧输送的增加幅度均大于汉族人。与汉族组相比，藏族人更高的脑氧输送伴随着更高的运动峰值能力。我们的研究结果表明，高海拔地区藏族终身居民对运动的脑血流反应得以维持。
