顶核—延髓头端腹外侧区系统参与前庭降压降心率反应

实验用乌拉坦麻醉、箭毒化、人工呼吸的大鼠。将神经元胞体兴奋剂L-谷氨酸钠(Glu)微量注入顶核或前庭上核均引起血压下降;心率减慢。该顶核-和前庭上核-降压降心率反应均可被延髓头端腹外侧区内注射GABA受体阻断剂荷包牡丹碱阻断。顶核内注射普鲁卡因也能阻断Glu兴奋前庭上核的心血管反应。以上结果提示前庭-降压降心率反应可能通过顶核-延髓头端腹外侧区系统实现。静脉注射甲基阿托品也能衰减Glu兴奋顶核的心血管反应,显示迷走神经也参与前庭-顶核降压降心率反应。

NUCLEUS EASTIGIUS-ROSTRAL VENTROLATERAL MEDULLA SYSTEM IS INVOLVED IN VESTIBULAR DEPRESSOR AND BRADYCARDIA RESPONSES

In urethane-anesthetized, tubocurarine-immobilized and artificially venti-lated rats, microinjection of L-glutamate (Glu) into the nucleus fastigius or nu-cleus vestibular superior caused a depressor and bradycardia response. Both thedepressor and bradycardia responses of the nucleus fastigius and nuclcus vestibu-laris superior were blocked by preinjection of bicuculline (a GABAergic receptorblocker) into the rostral ventrolateral medulla. And the cardiovascular responseinduced by excitation of the nucleus vestibularis superior could also be blocked byprocaine-injection into the nucleus fastigius. These results indicate that the ves-tibular depressor and bradycardia response was induced via the nucleus fastigius-rostral ventrolateral medulla system. Intravenous injection of methyl atropinealso markedly attenuated the cardiovascular response of the nucleus fastigius, in-dicating that the vagus nerve is also involved in the depressor and bradycardiaresponse of vestibulo-fastigial excitation.