Williams B A, Hanson M A
Department of Biochemistry and Physiology, University of Reading, UK.
J Dev Physiol. 1990 Mar;13(3):157-64.
We measured the reflex respiratory response to a 2-breath alternation in fractional inspired oxygen in two groups of lambs. Test runs where F(I),O2 was made to alternate (between 0.21 and 0.14) were compared with control runs in which it was held at 0.21. Within 36 h of birth we cut the carotid sinus nerves bilaterally in one group of lambs (n = 5) whilst in a second group (n = 5) sham operations were carried out. The alternating responses in seven respiratory variables were compared between test and control runs in each group of lambs at postnatal days 5-6 and again at postnatal days 10-11. In sham-operated lambs at days 5-6 there was a significant response in most respiratory variables during test runs and by days 10-11 the response was increased, primarily as a consequence of an increase in the tidal volume component of the response, indicating a postnatal maturation of the responses. The time-scale of this maturation is appropriate to that of peripheral chemoreceptor resetting. There was no significant response to the test in the denervated lambs at 5-6 days but by days 10-11 a small response was measured in some variables. Our results therefore indicate that the reflex respiratory response to alternations in FI,O2 is primarily mediated by the carotid chemoreceptors. The development of a response mediated by the aortic chemoreceptors may account for the small alternating response in the denervated lambs at days 10-11.
我们在两组羔羊中测量了对吸入氧分数中两次呼吸交替的反射性呼吸反应。将吸入氧分数（F(I)O2）交替（在0.21和0.14之间）的测试运行与将其保持在0.21的对照运行进行比较。在出生后36小时内，我们对一组羔羊（n = 5）双侧切断颈动脉窦神经，而对另一组羔羊（n = 5）进行假手术。在出生后第5 - 6天以及再次在出生后第10 - 11天，比较每组羔羊测试运行和对照运行之间七个呼吸变量的交替反应。在假手术的羔羊中，在出生后第5 - 6天的测试运行期间，大多数呼吸变量有显著反应，到出生后第10 - 11天反应增强，主要是由于反应的潮气量成分增加，表明反应的产后成熟。这种成熟的时间尺度与外周化学感受器重置的时间尺度相适应。在去神经支配的羔羊中，出生后第5 - 6天对测试没有显著反应，但到出生后第10 - 11天，在一些变量中测量到了小的反应。因此，我们的结果表明，对F(I)O2交替的反射性呼吸反应主要由颈动脉化学感受器介导。由主动脉化学感受器介导的反应的发展可能解释了去神经支配的羔羊在出生后第10 - 11天的小交替反应。
