【摘要】 用常规细胞内记录技术,对蟾蜍椎旁神经节胆碱能传递进行了系统的观察。发现第八或第九椎旁神经节中几乎所有细胞对节前神经刺激有快兴奋性突触后电位(f-EPSP)反应,其电生理和药理学特征与牛蛙标本的结果类似。约60％的细胞,节前神经刺激还引起受阿托品阻抑的慢兴奋性突触后电位(s-EPSP),多数情况下它与肽能性迟慢兴奋性突触电位的起始部相叠加。适宜频率(20—80Hz)刺激下,单纯的s-EPSP幅度与刺激脉冲个数成正比,其电生理特征符合钾电导失活为主要生电机制的假说。所有受试细胞,节前刺激不能引起可见的慢抑制性突触后电位(s-IPSP),压力注射乙酰胆硷能产生药理性质类似于f-EPSP和s-EPSP的电位,但不能产生超极化电位。因而,与牛蛙不同,蟾蜍交感节细胞可能缺乏这种抑制性胆硷能突触机制。更多还原

【Abstract】 Experimental observations on three types of cholinergic transmission in paravertebral ganglia(PVG)of the toad were made by using intracellular recording techniques. It was found that fast synaptic responses constantly existed in the cells of 8th or 9th PVG and the electrophysiological and pharmacological nature of the response was similar to that of fast EPSP in sympathetic ganglia of the bullfrog. Secondly, an atropine sensitive slow excitatory postsynap ic potential (s-EPSP) was recorded in 60% (27/45) cells sampled. The s-EPSP often overlapped on the initial part of a peptidergic slow potential (ls-EPSP). The amplitude of a pure s-EPSP was almost lineally related to the number of stimuli of a short train (2--5 s) delivered to the preganglionic nerves if optimum freauency (20--80 Hz)was used. With a standard stimulation (30 Hz, 101 pulses), the s-EPSP showed an amplitude of 5.3±0.6 mV (X±SE, n=6) and a duration of 29.2±3.4s. In the maiority of cells, the electrophysiological characteristics of the s-EPSP recorded were in agreement with a hypothesis that the electrogenesis of the slow potential was essentially resulted from inactivation of a potassium conductance. The s-EPSP recorded was closely mimicked by exogenous ACh-induced slow potential. Lastly, on the other hand, the slow inhibitory postsynaptic potential (s-IPSP) was not observed in the preparation used under nicotinic blockade. Our findings supported a point of view that variations exist amongst animal species not only in peptidergic but also in slow cholinergic ganglion transmissions.更多还原