Jansen A H, Belik J, Ioffe S, Chernick V
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
Am J Physiol. 1989 Oct;257(4 Pt 2):H1132-9. doi: 10.1152/ajpheart.1989.257.4.H1132.
The role of peripheral chemoreceptors in the circulatory adaptation to hypoxia and the effects of rapid-eye-movement (REM) and non-REM (NREM) sleep and breathing activity on organ blood flow were assessed in fetal sheep. Blood flow was measured with isotope-labeled microspheres on intact, vagotomized (VX), and sinoaortic-denervated (SAD) fetuses. Denervation did not change the biventricular cardiac output (Biv. CO) or organ blood flows during normoxia. In intact fetuses the blood flow was increased during hypoxemia in brain, adrenals, and heart but not in kidneys, skeletal muscles, or placenta. The increase in organ blood flow during hypoxemia was reduced in the VX group and even more in SAD fetuses, but in the latter group, blood flow was still increased in mid-brain, medulla, pons, skeletal muscles, and heart. Sleep states per se did not significantly affect the blood flow to any organs tested. However, the Biv. CO and blood flow to all organs except kidneys and adrenals was increased during fetal breathing in REM sleep. We conclude that 1) during moderate hypoxemia both aortic and carotid bodies plus an additional mechanism are involved in redistributing fetal blood flow, and 2) changes in organ perfusion during REM sleep are due to concomitant fetal breathing.
在胎羊中评估了外周化学感受器在循环系统对缺氧适应中的作用，以及快速眼动（REM）和非快速眼动（NREM）睡眠与呼吸活动对器官血流的影响。使用同位素标记的微球测量完整、迷走神经切断（VX）和去窦主动脉神经（SAD）胎儿的血流。在常氧状态下，去神经支配并未改变双心室心输出量（Biv.CO）或器官血流。在完整胎儿中，低氧血症时脑、肾上腺和心脏的血流增加，但肾脏、骨骼肌或胎盘的血流未增加。VX组低氧血症时器官血流的增加减少，SAD胎儿减少得更多，但在后一组中，中脑、延髓、脑桥、骨骼肌和心脏的血流仍增加。睡眠状态本身对所测试的任何器官的血流没有显著影响。然而，在REM睡眠中的胎儿呼吸期间，Biv.CO以及除肾脏和肾上腺外所有器官的血流均增加。我们得出结论：1）在中度低氧血症期间，主动脉体和颈动脉体以及另一种机制参与胎儿血流的重新分布；2）REM睡眠期间器官灌注的变化是由于伴随的胎儿呼吸。
