兔迷走传入成分对氨刺激鼻粘膜引起的心血管反应的影响

氨刺激清醒、制动兔的鼻粘膜引起明显的心率减慢和动脉血压升高反应(cardiovascular responses inducedby stimulating the nasal mucous membrane with ammonia,CVRA)。在Urethan全身麻醉作用下,CVRA明显减弱。切断双侧颈迷走神经干的兔,CVRA的心率减慢反应显著减弱,但不影响动脉血压升高反应。电刺激一侧颈增走神经中枢端或膈下迷走神经中枢端时,对CVRA显出抑制性影响,而刺激一侧减压神经使减压反射增强时,CVRA迷强。刺激喉上或喉返神经中枢端对CVRA无影响。上述结果表明,在兔的CVRA中,心率减慢和动脉血压升高反应是同时发生的两个神经过程,支配心血管活动的迷走和交感系统以特殊的组合方式产生整合作用,并对中枢麻醉作用表现出不同的敏感性。在迷走神经的传入成分中,来自不同部位的迷走传入冲动对兔的CVRA产生不同的作用,在整体活动的调节中它们可能以不同的整合方式对心血管活动产生影响。

Effects of Afferent Components of Vagal System on the Cardiovascular Responses Induced by the Stimulation of the Nasal Mucous Membrane with Ammonia in Rabbits

Slowdown in heart rate and rising of arterial blood pressure were successfully induced by stimulating the nasal mucous membrane with ammonia vapour in rabbits with its respiration kept artificially and immobilized by the use of relaxant. For convenience, cardiovascular responses to ammonia is abbreviated to CVRA. In one experiment, bilateral cervical vagotomy reduced markedly the extent of the bradycardiac reaction of CVRA, while the hypertensive change of CVRA remained unaltered after the same operation. The fact indicates that in CVRA, change of the heart rate and that of blood pressure are originally on their own and resulted from a specific integration action of vagal and sympathetic systems. In another experiment, it was found that stimulation of the cent- ral end of the cervical or subdiaphragmatic vagus give rise to an inhibitory effect on CVRA. But differing from this, enhacement of CVRA could be attende with stimulatin the depressot nerve. No effects on CVRA were observed, whend the superior or recurrent laryngeal nerves were stimulated. Thus, different afferent components of vagal system are varied in relation to CVRA. As to the action of general anesthesia. It has been found that anesthetic effects on CVR A differ from that on the depressor reflex, While both the cardiac and vascular reactions in the former were weakened conspicuously under the action of urethan, only the cardiac reaction in the latter was affected. The study has led to the conclusion that different components of the vagal and sympathetic systems have different susceptibility to general anesthesia, and their substantial effects are flexible, determined by their exciting functional states.