Possible role of prostaglandin E1 on adrenergic neurotransmission in the guinea-pig taenia coli.

The effects of prostaglandin (PG) E1 were investigated on the responses to adrenergic and non-adrenergic inhibitory nerve stimulation using the perivascular nerve-taenia preparation of the guinea pig. PGE1 caused a rapid and sustained contraction and markedly inhibited the response to adrenergic but not to non-adrenergic inhibitory nerve stimulation. It was also observed that PGE1 had some desensitizing action to exogenous noradrenaline on the postjunctional site. Although indomethacin decreased the tone of the preparation, it potentiated the response to adrenergic nerve stimulation without any effects on the response to non-adrenergic inhibitory nerve stimulation. From these observations, it was concluded that endogenous PGE1 may also play a regulatory role in adrenergic inhibitory neurotransmission, mainly by inhibitory action on noradrenaline release and partly by a similar action on the postjunctional site.