氨刺激兔鼻粘膜引起心血管反应的神经机制分析

为了进一步研究氨刺激兔鼻粘膜引起心血管反应(CVRA)的神经机制,特别是心交感神经的作用,在38只兔身上观察了心率和动脉血压的变化,吸入氨可引起心率减慢和动脉血压升高。切断双侧颈迷走神经后吸氨时心率减慢反应仍存在,静注心得安后吸氨时心率减慢反应消失.静注酚妥拉明后吸氨时血压上升程度明显减小。去除缓冲神经后仍引起 CVRA,电刺激一侧减压神经中枢端引起心率减慢和血压下降。离断嗅叶后 CVRA 不变,离断中脑后 CVRA 减弱。结果表明:在 CVRA 中,冲动经三叉神经传至脑桥和延髓引起心迷走中枢和交感缩血管中枢兴奋,心交感中枢抑制。高位中枢对 CVRA 可能有易化作用。减压反射与 CVRA 的中枢机制不同。因此可以认为在完整机体中,各种环境刺激引起的心血管反应都各表现为特殊但又有规律的整合型式。

An Analysis of Nervous Mechanism of Cardiovascular Response Induced by Ammonia Stimulation of Nasal Mucous Membrane in Rabbits

To assess nervous mechanism responsibility for cardiovascular response induced by ammonia stimulation of nasal mucous membr- ane(CVRA),especially the effect of the cardio-sympathetic nervous system.Changes in heart rate and blood pressure were observed on 38 rabbits.Inhalation of ammonia resulted in bradycardia and increased in blood pressure.The bradycardia was not abolished by bilateral vagotomy but was done by injection of propranolol.The response of blood pressure was reduced by iujection of phentolamine.After severed the buffer nerve,the CVRA was the same but bradycardia and a decrease in blood pressure was induced by electric stimulation of the central end of depressor nerve.The CVRA was not changed by olfactory bulb section but was depressed by midbrain section.These results suggest that integration of trigeminal input occurs at pons medulla;the excitation of cardio-vagal centre and sympathetic constrictor centre and inhibition of cardio-sympathetic centre activity occurs during CVRA.The CVRA may be facilitated by higher central nervous system.The central mechanism of the CVRA differs from that of the depressor reflex.It may be concluded that in intact animal the cardiovascular response iuduced by various environmetal stimuli appears in characteristic and regular integrative patterns.