RELEASE OF PROSTAGLANDIN E FROM THE ISOLATED URINARY BLADDER OF THE GUINEA‐PIG

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Abstract
Release of prostaglandin E (PGE) from guinea‐pig urinary bladder in vitro has been demonstrated both in the resting state and during electrical stimulation. The electrically evoked release of PGE was significantly higher than the resting release and was frequency‐dependent. 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. 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. Indomethacin failed to inhibit the mechanical responses of the bladder to transmural stimulation. The present experiments suggest that PGE is not involved in mediating the non‐cholinergic non‐adrenergic neurotransmission in the guinea‐pig urinary bladder.