Release of prostaglandin E from the isolated urinary bladder of the guinea-pig.

1 Release of prostaglandin E (PGE) from guinea-pig urinary bladder in vitro has been demonstrated both in the resting state and during electrical stimulation. 2 The electrically evoked release of PGE was significantly higher than the resting release and was frequency-dependent. 3 The released substance was characterized as PGE pharmacologically by (a) blockade of its response by SC-19220 on guinea-pig ileum, (b) reduction of the amount of the released substance by indomethacin and (c) the inhibitory effect of the released substance on adrenergic neurotransmission in guinea-pig vas deferens. 4 The prostaglandin seemed to originate from the muscle since tetrodotoxin treatment did not abolish the release during direct muscle stimulation; however, concomitant release from neuronal tissue could not be excluded in the present experiments. 5 Indomethacin failed to inhibit the mechanical responses of the bladder to transmural stimulation. 6 The present experiments suggest that PGE is not involved in mediating the non-cholinergic non-adrenergic neurotransmission in the guinea-pig urinary bladder.