Bach K B, Mitchell G S
Department of Comparative Biosciences, University of Wisconsin, Madison 53706, USA.
Respir Physiol. 1996 Jul;104(2-3):251-60. doi: 10.1016/0034-5687(96)00017-5.
Repeated isocapnic hypoxia evokes long-term facilitation (LTF) of phrenic nerve activity in rats. We wished to determine: (1) whether hypoxia-induced LTF is serotonin dependent; and (2) whether hypoxia-induced LTF is a property of upper airway motoneurons. Phrenic and hypoglossal nerve activities were recorded in urethane anesthetized, vagotomized, paralyzed and artificially ventilated rats (n = 7). Rats were exposed to three, 5-min hypoxic episodes (FIo2 = 0.10) separated by 5 min of hyperoxia (FIo2 = 0.50). One hour after the final hypoxic episode, integrated phrenic and hypoglossal amplitudes and burst frequency were increased above control values (63 +/- 17%, 78 +/- 26% and 9.6 +/- 2.1 bursts/min, respectively: p < 0.05). In rats pretreated with methysergide (n = 7; 4 mg/kg), no changes in phrenic or hypoglossal activity from pre-stimulus control values were observed at any time post-stimulation. The results indicate that hypoxia-induced LTF requires 5-HT receptors and is characteristic of both hypoglossal and phrenic motor output.
反复的等碳酸血症性低氧可引起大鼠膈神经活动的长期易化（LTF）。我们希望确定：（1）低氧诱导的LTF是否依赖于5-羟色胺；以及（2）低氧诱导的LTF是否是上呼吸道运动神经元的一种特性。在氨基甲酸乙酯麻醉、迷走神经切断、麻痹并人工通气的大鼠（n = 7）中记录膈神经和舌下神经活动。大鼠暴露于三次5分钟的低氧发作（吸入氧分数=0.10），每次发作间隔5分钟的高氧（吸入氧分数=0.50）。在最后一次低氧发作后1小时，膈神经和舌下神经的积分幅度和爆发频率均高于对照值（分别为63±17%、78±26%和9.6±2.1次/分钟：p<0.05）。在用麦角新碱预处理的大鼠（n = 7；4mg/kg）中，刺激后任何时间膈神经或舌下神经活动与刺激前对照值相比均未观察到变化。结果表明，低氧诱导的LTF需要5-羟色胺受体，并且是舌下神经和膈神经运动输出的特征。
