大鼠脑桥呼吸调整中枢神经元对低氧呼吸反应的调节作用

Effects of pontine pneumotaxic center on hypoxia respiratory response

目的探讨大鼠脑桥呼吸调整中枢神经元N-甲基-D-天氡氨酸(NMDA)受体及γ-氨基丁酸(GABA)受体对低氧呼吸反应的调节作用。方法通过显微注射技术向大鼠脑桥呼吸调整中枢内微量注射NMDA受体阻断剂D-2-氨基-5-磷酸基戊酸(D-AP5)和GABA受体阻断剂荷包牡丹碱(BIC),观察其对低氧呼吸反应膈神经放电的影响。结果脑桥微量注射D-AP5后,急性低氧反应膈神经放电无显著性改变,但低氧后呼气时间延长的幅度及呼吸频率下降的幅度均减小(P均<0.05),低氧后呼吸频率下降(PHFD)被削弱;脑桥微量注射BIC后,急性低氧反应膈神经放电频率升高的幅度及呼吸时间缩短的幅度均增大(P均<0.05),PHFD无显著性改变。结论大鼠脑桥呼吸调整中枢神经元NMDA受体介导的突触传递主要影响PHFD,GABA受体介导的突触传递主要影响急性低氧反应。

Objective To investigate the role of NMDA and GABA receptors located in pontine pneumotaxic center neurons in peripheral chemoreflex. Methods Experments were done on rats to observe the effects of NMDA receptor antagonist D-2-amino-5-phosphonovaleric acid( D-AP5) and GABA receptor antagonist bicuculline( BIC) on the phrenic nerve discharges in peripheral chemoreflex by microinjecting the two antagonists into pontine. Results The post-hypoxic frequency decline( PHFD) was attenuated after microinjection of D-AP5 while the acute hypoxia response was not influnced. The rapid increase in respiratory frequency and the parallel shortening of expiratory time were enhanced after microinjection of BIC,while PHFD was not influenced. Conculsion Neurotransmissions mediated by NMDA and GABA receptors mainly modulate PHFD and the acute hypoxia response respectively.