Perinatal hyperoxia for 14 days increases nerve conduction time and the acute unitary response to hypoxia of rat carotid body chemoreceptors
Perinatal hyperoxia for 14 days increases nerve conduction time and the acute unitary response to hypoxia of rat carotid body chemoreceptors
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DOI：
10.1152/japplphysiol.01009.2004
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发表时间：
2005-07-01
影响因子：
3.3
通讯作者：
Carroll, JL
中科院分区：
文献类型：
--
作者：
Donnelly, DF;Kim, I;Carroll, JL
围产期的高氧血症与对急性缺氧的呼吸反应的终生损害有关，但在成年后不是。这种效应归因于外周化学感受器的功能损害，包括化学感受器传入纤维数量的减少和“全神经”传入活动的减少。本研究的目的是评估高氧后即刻单个化学感受器单位的活动水平，以确定功能损害是否延伸到单个化学感受器单位，以及这种损害是否仅由出生后即刻的高氧暴露引起。两组仔鼠分别在0-14天和14-28天暴露于60%激发的O-2组分2wk，在此期间分离并记录单个单位的体外活动。与对照组相比，高氧处理的幼鼠的基线(常氧)刺激性活动减少了10倍。与对照组相比，高氧组和高氧组对12、5和0%O-2的单位峰值反应均降低，神经传导时间明显减慢。我们的结论是：1)高氧显著降低常氧和急性缺氧时的单单位化学感受器活性，2)治疗效果不仅限于新生儿早期，3)这种损害至少部分可能是由于传入轴突兴奋性的改变所致。
Hyperoxia in the immediate perinatal period, but not in adult life, is associated with a life-long impairment of the ventilatory response to acute hypoxia. This effect is attributed to a functional impairment of peripheral chemoreceptors, including a reduction in the number of chemoreceptor afferent fibers and a reduction in "whole nerve" afferent activity. The purpose of the present study was to assess the activity levels of single chemoreceptor units in the immediate post-hyperoxic period to determine whether functional impairment extended to single chemoreceptor units and whether the impairment was only induced by hyperoxia exposure in the immediate postnatal period. Two groups of rat pups were exposed to 60% inspired O-2 fraction for 2 wk at ages 0 - 14 days and 14 - 28 days, at which time single-unit activities were isolated and recorded in vitro. Compared with control pups, hyperoxia-treated pups had a 10-fold reduction in baseline (normoxia) spiking activity. Peak unit responses to 12, 5, and 0% O-2 were reduced and nerve conduction time was significantly slower in both hyperoxia-treated groups compared with control groups. We conclude that 1) hyperoxia greatly reduces single-unit chemoreceptor activities during normoxia and acute hypoxia, 2) the treatment effect is not limited to the immediate newborn period, and 3) at least part of the impairment may be due to changes in the afferent axonal excitability.