Prostaglandin F 2α back transfer from the mesometrium vasculature into the uterus of the gilt during early pregnancy and estrogen-induced pseudopregnancy

Abstract

Isolated reproductive tracts from gilts on the days of luteal regression (13–17 day of estrous cycle), pregnant gilts (14–18 days of pregnancy) and estrogen-induced pseudopregnant gilts (15–18 day of estrous cycle) were supplied with autologous, oxygenated blood. 3H-PGF 2α (10 8 dpm) was infused at a constant rate into three different sites of the most superficial layer of the myometrium along the length of the horn close to the broad ligament. During infusion (60 min) and 60 min after the infusion had been stopped, arterial blood was collected continuously in 5-min samples from a small branch of the uterine artery in the mesometrium area about 10 cm from the uterine horn. A significantly higher concentration of 3H-PGF 2α in the uterine-artery blood plasma was found in pseudopregnant and pregnant gilts than in the control group. The total 3H-PGF 2α back transfer with arterial blood from the broad ligament vasculature into the uterus was 2.4 × 10 6 dpm, 6.0 × 10 6 dpm and 19.8 × 10 6 dpm of infused 3H-PGF 2α in the control, pregnant and pseudopregnant gilts, respectively. We suggest that ability for PGF 2α binding and back transfer from the broad ligament vasculature into the uterus, as observed in pseudopregnant and pregnant gilts, may strongly reduce the peak concentration during the pulsatile release of PGF 2α from the uterus and may protect the corpus luteum against luteolysis.