Effects of prostaglandin E1 and indomethacin on the stimulation-evoked overflow of 3H-noradrenaline from guinea-pig taenia.

Prostaglandin E1 (5.8 X 10(-8) M) markedly and reversibly reduced the stimulation-evoked overflow of total tritium, while it had no effects on basal outflow. Indomethacin (8.4 X 10(-6) M) increased the stimulation-evoked overflow of total tritium at low frequencies (2--5 HZ), while it had no effect at high frequencies of stimulation (more than 10 HZ). It was concluded that endogenous prostaglandin E1 also plays a regulatory role in adrenergic inhibitory neurotransmission by inhibiting the noradrenaline release from adrenergic nerve terminals of the guinea-pig taenia caecum.