Engel B T, Talan M I
Laboratory of Behavioral Sciences, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224.
Acta Physiol Scand. 1991 Feb;141(2):273-8. doi: 10.1111/j.1748-1716.1991.tb09077.x.
We analysed the haemodynamic patterns of seven monkeys (Macaca mulatta) during a one-month period during which we monitored beat-to-beat levels of heart rate, stroke volume, intra-arterial pressure and central venous pressure 7 days/week, 18 h/day. We replicated an earlier finding that cardiac output falls and total peripheral resistance rises throughout the night: the fall in cardiac output was mediated by a fall in heart rate since stroke volume did not change; and the rise in peripheral resistance reflected a homeostatic adjustment to the fall in cardiac output since blood pressure was stable throughout the night although it fell early in the evening. In addition, we have shown for the first time that central venous pressure also falls throughout the night; this occurs even in the presence of alpha- and beta-adrenergic sympathetic blockade. Since stroke volume does not change overnight this indicates that the nocturnal fall in cardiac output is not due to a shift of blood volume into the venous compartment. These findings support our hypothesis that there is a nocturnal decline in plasma volume.
我们分析了7只猕猴（恒河猴）在为期1个月的时间段内的血流动力学模式，在此期间，我们每周7天、每天18小时监测逐搏的心率、每搏输出量、动脉内压力和中心静脉压水平。我们重复了之前的一项发现，即整个夜间心输出量下降而总外周阻力上升：心输出量的下降是由心率下降介导的，因为每搏输出量没有变化；外周阻力的上升反映了对心输出量下降的一种稳态调节，因为尽管血压在傍晚早期下降，但整个夜间血压是稳定的。此外，我们首次表明，中心静脉压在整个夜间也会下降；即使在存在α和β肾上腺素能交感神经阻滞的情况下也是如此。由于每搏输出量在夜间没有变化，这表明夜间心输出量的下降并非由于血容量转移到静脉腔所致。这些发现支持了我们的假设，即血浆量在夜间会下降。
