Role of endogenous and exogenous prostaglandins on the contractile functioning of isolated sow (Sus scrofa) oviducts.

The output of prostaglandins (PGs) E1, E2 and F2 alpha, from ampullary and isthmic portions of sow oviducts isolated during proestrus, estrus and metestrus, was explored. Moreover, in vitro cumulative dose-response curves for the contractile effect of these three PGs, on identical oviductal segments, were constructed. Isthmic preparations from proestrous and metestrous animals released more PGE1 and PGF2 alpha than PGE2 "like material". During estrus, the outputs of PGE1, PGE2 and PGF2 alpha were similar, whereas, oviducts from proestrous and metestrous sows released less PGE1 and PGF2 alpha than during estrus. Although the output of PGE2 "like material" from isthmic and ampullary segments did not differ significantly during the three stages of the sex cycle, ampullary metestrous preparations released more PGE1 and PGF2 alpha, than estrous or proestrous ones. The addition of PGE1, PGE2 or PGF2 alpha, consistently stimulated the amplitude of contractions of isthmic oviductal segments isolated from proestrous and metestrous sows. Within the concentration-range explored, dose-response curves for PGE2 and PGE1 were to the left of those for PGF2 alpha in the isthmus obtained before ovulation (proestrus) but not in segments isolated at later times (2-3 days) of the cycle (metestrus). The stimulatory dose-response curves for PGE1, or PGE2, in isthmic segments of metestrous preparations incubated with phentolamine (10(-6)M) were shifted to the right of controls not exposed to the adrenoreceptor blocker, whereas, the curve for PGF2 alpha without phentolamine, was identical to that obtained in its presence. PGE1 and PGE2 did not evoke significant contractile effects on oviductal ampullary portions from proestrous sows, whereas, PGF2 alpha was clearly stimulatory at concentrations of 10(-9)M and higher. In ampullary segments isolated after ovulation (metestrus) the threshold for contractile enhancement following PGF2 alpha was greater than during proestrus, whereas, PGE1 elicited a significant inhibition of contractions. The spontaneous contractile pattern exhibited by isthmic and ampullary oviductal regions, prior to and after ovulation, is discussed in terms of tissue PG generation and output and is compared with results regarding tubal motility following the exposure to exogenous PGs.