电和L—谷氨酸钠刺激兔中缝隐核对膈神经放电的影响

实验在45只麻醉、自主呼吸、断双侧颈迷走神经的家兔上进行。电刺激或微量注射L-谷氨酸钠于中缝隐核(Nucleus raphe obscurus,NRO),观察到:(1)长串电脉冲刺激NRO(50—200μA,波宽0.3ms,100Hz,4—6s),出现膈神经放电被抑制的反应,被抑制的程度与刺激强度、刺激频率间存在相关性。(2)吸气期用短串电脉冲(100—200μA,波宽0.3ms,50—100Hz,5—20个脉冲)刺激NRO,可提前终止膈神经放电,产生吸气切断效应。吸气切断时间具有刺激落位和刺激强度依赖性。(3)NRO内微量注射细胞体兴奋剂谷氨酸钠(1mol/L,1μl),注药期间出现膈神经放电抑制,注药后为吸气时程(Ti)缩短和呼气时程(Te)延长。

EFFECT OF ELECTRICAL AND L-GLUTAMATE STIMULATION OF NUCLEUS RAPHE OBSCURUS ON PHRENIC NERVE ACTIVITY IN RABBITS

Experiments were performed on 45 urethane-anesthetized, vagotomized and spontaneously breathing rabbits. By electrical stimulation of or microinjection of L-glutamate into nucleus raphe obscurus (NRO), the following results were observed: (1) A long stimulus train (50-200 microA, 100Hz, 4-6 s) delivered to NRO resulted in a decrease in integrated phrenic amplitude (IPA) or complete cessation of phrenic nerve discharge. The decrease of IPA was dependent upon current intensity and frequency of stimulation. (2) Short train stimulation (100-200 microA, 50-100 Hz, 5-20 pulses) delivered to NRO during the inspiratory phase terminated this phase prematurely, i.e., inspiratory off-switch (IO-S). The IO-S time varied according to the current intensity and the delivery time of stimulation in the inspiratory phase. (3) Microinjection of L-glutamate (1 mol/L, 1 microliter) into NRO caused a transient depression of phrenic nerve activity followed by a shortening of inspiratory time (Ti) and a lengthening of expiratory time (Te).