The influence of prostaglandins on neurotransmission in the rabbit isolated vas deferens.

Arachidonic acid and PGs of the D, E, F and I series were examined for influences on neurogenic contractions of the rabbit isolated vas deferens. This preparation exhibits two pharmacologically distinct contractions in response to electrical stimulation. All of the PGs tested inhibited the neurogenic contractions but the pattern of inhibition differed. PGE1 and PGI2 inhibited the adrenergic contractile phase more potently than the nonadrenergic, and PGF2 alpha exhibited the opposite selectivity. Arachidonic acid, PGE2 and PGD2 produced equipotent effects on both contractile phases, although PGE2 was the most potent in producing these effects. None of the PGs altered the concentration-response curve to norepinephrine. Contractile responses to ATP, a putative neurotransmitter, were inhibited by PGF2 alpha but not by the other PGs. These results suggest that the PG effects are predominantly prejunctional. The differing potencies of the PGs on the two neural components are consistent with the hypothesis that neurotransmitters in the vas deferens are released by distinct types of nerves.