1973 年 110 巻 2 号 p. 119-138
Electrophysiological and pharmacological nature of smooth muscle of guinea-pig and rabbit stomach was investigated by means of intracellular microelectrode technique. 1) The mean values of the resting potential were -46.4 and -57.3 mV in rabbit and guinea-pig, respectively. 2) Spike had an overshoot and was characterized by slower rising and faster falling phases followed by undershoot. 3) The latency of ejp ranged from 100 to 170 msec. Ejp was abolished by atropine but not by dTC. 4) A typical single ijp was 105 msec in latency, 0.48 and 3 sec in hyperpolarizing and repolarizing times, respectively. 5) Neither α-nor β-adrener-gic blockers were effective for ijp and PIO. 6) Chronaxie and rheobase were not so different for both ejp and ijp. 7) The thresholds for ijps measured from the cells at three different positions to a given stimulus point were almost the same. 8) Ijp was reversibly abolished by TTX. 9) By lowering Ca/Mg ratio ijp reduced in amplitude. 10) No significant effect of strychnine on both ijp and P10 -was observed. 11) Both ejp and ijp decreased in amplitude by adrenalin. It was concluded that ijp is mediated by some transmitter released from inhibitory postsynaptic neuron of noncholinergic and nonadrenergic nature.
