Saiki C, Mortola J P
Department of Physiology, McGill University, Montreal, Quebec, Canada.
Pediatr Res. 1994 Apr;35(4 Pt 1):490-3.
We asked whether the ventilatory control of the newborn rat was modified by preceding daily episodes of anoxia. At thermoneutrality (ambient temperature, 32 degrees C) during anoxia, respiratory efforts lasted, on average, 28, 20, and 11 min at 1, 3, and 7 d, respectively. Therefore, we chose 10 min as the duration of a daily exposure to anoxia (100% N2 breathing) from d 1 to d 6 (experimental group). During the 7 d of the study, body growth was not different between the two groups. On d 7, respiratory measurements were performed and compared with those of rats never exposed to anoxia (controls). In normoxia, oxygen consumption (VO2, measured with an open-flow system) and ventilation (VE, measured by flow-plethysmography) were similar between control and experimental groups. Acute exposure to hypoxia (10 min of 10% O2) resulted in a similar drop in VO2 and increase in VE in both groups. During the last exposure to anoxia on d 7, heart rate and breathing rate rapidly dropped; the attained degree of acidosis (blood pH and PCO2) was also similar to that of control rats. The results of the present experimental approach suggest that, in the newborn rat, daily episodes of anoxia during the 1st postnatal wk have no appreciable impact on body growth, ventilatory control, and the response to additional hypoxia.
我们探究了新生大鼠的通气控制是否会因之前每日的缺氧发作而改变。在缺氧期间的热中性温度（环境温度32摄氏度）下，1日龄、3日龄和7日龄大鼠的呼吸努力平均分别持续28分钟、20分钟和11分钟。因此，我们选择从第1天到第6天，每天让大鼠暴露于缺氧环境（呼吸100%氮气）10分钟作为缺氧暴露时长（实验组）。在研究的7天里，两组大鼠的身体生长情况并无差异。在第7天，进行呼吸测量，并与从未暴露于缺氧环境的大鼠（对照组）进行比较。在常氧状态下，对照组和实验组的耗氧量（VO2，采用开放流动系统测量）和通气量（VE，通过体积描记法测量）相似。急性暴露于低氧环境（10%氧气，持续10分钟）会使两组大鼠的VO2出现相似程度的下降，VE增加。在第7天最后一次暴露于缺氧环境期间，心率和呼吸频率迅速下降；所达到的酸中毒程度（血液pH值和PCO2）也与对照大鼠相似。本实验方法的结果表明，对于新生大鼠，出生后第一周每天的缺氧发作对身体生长、通气控制以及对额外低氧的反应没有明显影响。
