Olson E B
John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin, School of Medicine, Madison 53705.
Life Sci. 1988;42(15):1469-76. doi: 10.1016/0024-3205(88)90057-4.
Awake, adult male rats (some with chronically indwelling femoral artery catheters) were exposed for up to 7 days to one of three environments: a) normoxia (PIO2 = 155 Torr), b) hypoxic hypocapnia (PIO2 = 90 Torr), and c) hypoxic normocapnia (PIO2 = 73 Torr, PICO2 = 32 Torr), and arterial blood gas and acid-base status were documented. After 1 hour to 7 days, rats were sacrificed, and the time courses of the brain levels and turnovers of norepinephrine (NE), dopamine (DA) and serotonin (5-hydroxytryptamine or 5HT) were determined in each condition. The transient decrease in monoamine levels seen on exposure to acute hypoxia was absent if normocapnia was maintained; 7 days hypoxia with or without hypocapnia resulted in increased monoamine levels. Normocapnia also prevented an immediate, sustained decrease in 5HT turnover and a delayed decrease in DA turnover which were observed in hypoxic hypocapnia. A delayed increase in 5HT turnover appeared to be due to hypoxia independent of PaCO2. Therefore, the initial, transient loss of mental acuity and some ventilatory adaptations observed during prolonged hypoxia may be a result of the decrease in PaCO2 rather than the decreased oxygen concentration.
将成年雄性清醒大鼠（部分大鼠长期留置股动脉导管）暴露于以下三种环境之一长达7天：a）常氧（吸入氧分压=155托），b）低氧低碳酸血症（吸入氧分压=90托），c）低氧正常碳酸血症（吸入氧分压=73托，动脉血二氧化碳分压=32托），并记录动脉血气和酸碱状态。在1小时至7天后，处死大鼠，测定每种情况下去甲肾上腺素（NE）、多巴胺（DA）和5-羟色胺（5-HT）的脑内水平和周转率的时间进程。如果维持正常碳酸血症，暴露于急性低氧时所见的单胺水平短暂下降则不会出现；伴有或不伴有低碳酸血症的7天低氧导致单胺水平升高。正常碳酸血症还可防止在低氧低碳酸血症中观察到的5-HT周转率立即持续下降和DA周转率延迟下降。5-HT周转率延迟增加似乎是由于与动脉血二氧化碳分压无关的低氧所致。因此，在长时间低氧期间观察到的初始短暂精神敏锐度丧失和一些通气适应可能是动脉血二氧化碳分压降低而非氧浓度降低的结果。
