兔心迷走神经传出放电的活动特征

兔心迷走神经传出放电有三种类型:1.与后膈神经传出发放同步的节律性放电。这种节律性发放包含两个时相,第一时相大致与膈神经传出放电同时起止,第二时相在膈神经传出发放后期或发放终止时出现。2.持续性放电,出现在上述节律性放电的间歇期。3.偶然出现的高幅高频暴发放电。这种放电出现时,膈神经传出放电即受到明显的压抑。开放预先夹闭的颈总动脉使心迷走神经传出放电增强。窒息、静脉注射肾上腺素使心迷走神经传出放电增强,心率减慢;扩张肺、过度通气、吸入亚硝酸异戊酯使心迷走神经传出放电减少,心率增快。

CHARACTERISTICS OF EFFERENT DISCHARGE ACTIVITY IN CARDIAC VAGAL NERVE OF THE RABBIT

Three types of discharge pattern were recorded from the cardiac vagal efferentnerve of the rabbit immobilized with flaxedil.1.Rhythmic discharges synchronizedwith the efferent impulses of the phrenic nerve.Two phases were distinguishedduring each discharge period:the first phase was roughly simultaneous with thephrenic efferent flow,and the second one developed during the later period of thephrenic efferent discharges or immediately after the end of the phrenic discharge.2.Continuous discharges.3.Occasional discharges with high amplitude andfrequency.The phrenic efferent discharges were obviously depressed wheneverthe burst appeared.An increase in the activity of the cardiac branch of the vagus could be inducedby release of the occluded common carotid arteries.An enhanced discharge in thecardiac vagus and a decreased heart rate could be induced by asphysia and intrave-nous injection of adrenaline.On the other hand,the vagal discharges could bedepressed and the heart rate increased by inflation of the lungs,hyperventilationand amyl nitrite inhalation.