McIsaac R J, Wong K K
Arch Int Pharmacodyn Ther. 1984 Mar;268(1):32-45.
Repetitive stimulation of the preganglionic nerve of the rat superior cervical sympathetic ganglion potentiates the amplitude of asynchronous firing elicited by the muscarinic agonist, bethanechol. The amplitude of stimulus-induced facilitation is not related to frequency of stimulation and occurs with a stimulation frequency of 10 Hz or greater. Facilitation, but not the asynchronous firing is reduced by lowering the temperature of the bathing solution. Dibutryl cyclic adenosine monophosphate and theophylline had no effect on asynchronous firing but reduced stimulus-induced facilitation. Neither dibutryl cyclic guanosine monophosphate up to 1 mM nor nitroprusside had any significant effect on bethanechol-induced asynchronous firing or stimulus-induced facilitation. Tetraethylammonium caused a 200% increase in stimulus-induced facilitation. Acetylcholine, in a concentration that elicited maximum nicotinic firing, had no effect on the magnitude of bethanechol-induced asynchronous firing. Increased Ca++, Mg++ or Mn++ reduced both asynchronous firing and stimulus-induced facilitation. It is concluded that facilitation is a result of transmitter release, possibly not acetylcholine.
反复刺激大鼠颈上神经节的节前神经可增强毒蕈碱激动剂氨甲酰甲胆碱引发的异步放电幅度。刺激诱导的易化幅度与刺激频率无关，在10Hz或更高的刺激频率下出现。降低灌流液温度可降低易化作用，但不影响异步放电。二丁酰环磷腺苷和茶碱对异步放电无影响，但可降低刺激诱导的易化作用。高达1mM的二丁酰环磷鸟苷和硝普钠对氨甲酰甲胆碱诱导的异步放电或刺激诱导的易化作用均无显著影响。四乙铵可使刺激诱导的易化作用增加200%。能引发最大烟碱样放电的乙酰胆碱浓度对氨甲酰甲胆碱诱导的异步放电幅度无影响。细胞外Ca++、Mg++或Mn++浓度增加可降低异步放电和刺激诱导的易化作用。由此得出结论，易化作用是递质释放的结果，可能不是乙酰胆碱。
