Intermittent hypoxia augments carotid body and ventilatory response to hypoxia in neonatal rat pups
Intermittent hypoxia augments carotid body and ventilatory response to hypoxia in neonatal rat pups
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DOI：
10.1152/japplphysiol.00876.2003
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发表时间：
2004-11-01
影响因子：
3.3
通讯作者：
Prabhakar, NR
中科院分区：
文献类型：
--
作者：
Peng, YJ;Rennison, J;Prabhakar, NR
颈动脉体在出生时功能不成熟，对缺氧的敏感性较差。先前的研究表明，出生时持续缺氧会损害颈动脉体的缺氧感知。间歇性缺氧（IH）在新生儿生活中更常见。先前对成年动物的研究表明，IH 有助于颈动脉体的缺氧感知。在这些研究的基础上，在本研究中，我们测试了以下假设：新生儿 IH 促进颈动脉体的缺氧感知并增强对缺氧的通气反应。实验在出生后不久就暴露于 16 小时 IH 的 2 天大的幼鼠身上进行。 IH 范例包括 15 秒的 5% O-2（最低点），然后是 5 分钟的 21% O-2（9 次/小时）。在一组实验（IH 和对照，每组 n = 6 只幼犬）中，从离体颈动脉体记录感觉活动，而在另一组实验（IH 和对照，每组 n = 7 只幼犬）中，通过体积描记法监测未麻醉幼犬的通气情况。在对照幼犬中，颈动脉体的感觉反应较弱且发生缓慢（大约 100 秒）。相反，与对照幼犬相比，IH 幼犬颈动脉体对缺氧的感觉反应更大，反应时程更快（大约 30 秒）。与对照组相比，IH 组的缺氧通气反应程度更大，而缺氧期间 O-2 消耗和 CO2 产生的变化在两组之间相当。然而，高氧高碳酸血症（7% CO2 平衡 O-2）对通气刺激的强度在两组幼犬中是相同的。这些结果表明新生儿 IH 促进颈动脉体对缺氧的感觉反应并增强缺氧通气化学反射。
Carotid bodies are functionally immature at birth and exhibit poor sensitivity to hypoxia. Previous studies have shown that continuous hypoxia at birth impairs hypoxic sensing at the carotid body. Intermittent hypoxia (IH) is more frequently experienced in neonatal life. Previous studies on adult animals have shown that IH facilitates hypoxic sensing at the carotid bodies. On the basis of these studies, in the present study we tested the hypothesis that neonatal IH facilitates hypoxic sensing of the carotid body and augments ventilatory response to hypoxia. Experiments were performed on 2-day-old rat pups that were exposed to 16 h of IH soon after the birth. The IH paradigm consisted of 15 s of 5% O-2 (nadir) followed by 5 min of 21% O-2 (9 episodes/h). In one group of experiments (IH and control, n = 6 pups each), sensory activity was recorded from ex vivo carotid bodies, and in the other ( IH and control, n = 7 pups each) ventilation was monitored in unanesthetized pups by plethysmography. In control pups, sensory response of the carotid body was weak and was slow in onset ( similar to 100 s). In contrast, carotid body sensory response to hypoxia was greater and the time course of the response was faster ( similar to 30 s) in IH compared with control pups. The magnitude of the hypoxic ventilatory response was greater in IH compared with control pups, whereas changes in O-2 consumption and CO2 production during hypoxia were comparable between both groups. The magnitude of ventilatory stimulation by hyperoxic hypercapnia (7% CO2-balance O-2), however, was the same between both groups of pups. These results demonstrate that neonatal IH facilitates carotid body sensory response to hypoxia and augments hypoxic ventilatory chemoreflex.