Fluid Retention by the Rabbit Oviduct

Abstract

Abstract

Factors affecting occlusion of the isthmic portion of the oviduct in Dutch-belted rabbits were evaluated by measuring the amount of fluid that accumulated in oviducts that were ligated only at the ovarian end. Very little fluid accumulated in the oviducts of estrous rabbits. Induction of ovulation with human chorionic gonadotropin (hCG) or treatment with Depo-estradiol cypionate (ECP) caused a significant increase in the accumulation of tubal fluid at 48 hr. Indomethacin inhibited fluid retention in ECP-treated rabbits, but had no effect in rabbits injected with hCG. Progesterone antagonized the effect of hCG, but not that of ECP. The effect of progesterone in hCG-treated rabbits could not be attributed to a decrease in fluid secretion rate since the amount of fluid in oviducts that were ligated at both ends was similar in rabbits treated with hCG or hCG plus progesterone. In contrast to the results at 48 hr, indomethacin had no effect on fluid accumulation at 72 hr in ECP-treated rabbits. However, indomethacin did reduce the amount of fluid that accumulated in the oviducts of rabbits injected with both hCG and ECP. Prostaglandin (PG) E₁, PGE₂, and PGF_2α had no effect on fluid retention. These data indicate that an interaction exists between the occlusive effects of hCG and ECP. At 48 hr the effect of hCG seems not to be mediated by PGs, but the effect of ECP is PG related. However, at 72 hr the effect of ECP cannot be blocked by inhibiting PG synthesis, but the occlusive effect of hCG plus ECP may be mediated by PGs.