THE LOCAL ELEVATION OF ESTRONE AND ANDROSTENEDIONE CONCENTRATIONS IN THE BLOOD SUPPLYING THE OVIDUCT AND UTERUS ON DAYS 17-18 OF THE ESTRUSCYCLE OF GILTS

The concentrations of estrone and androstenedione were studied in bloo d samples collected from the branch of the uterine artery (anastomosed with the ovarian artery and supplying the oviduct and proximal to the ovary part of the uterus) and from the jugular vein, in anaesthetized and conscious gilts, on days 17-18 of the oestrus cycle. Simultaneous blood samples were collected as follows: (a) in anaesthetized animals every 5 min for 1 h immediately after catheters were inserted during surgery and every 10 min for 2 h following surgery; (b) from conscious animals on day 2 after surgery, every 10 min for 2 h in the morning a nd every 10 min for 2 h in the afternoon. Blood samples were assayed f or estrone and androstenedione by radioimmunoassay. The concentrations of estrone (mean +/- SEM) in blood collected from the branch of the u terine artery were significantly higher (16.8 +/- 0.9 pg/ml) than in t he jugular vein (10.1 +/- 0.5 pg/ml, p < 0.0001). The mean concentrati ons of androstenedione in the blood collected from the branch of uteri ne artery were significantly higher (139 +/- 6 pg/ml) than in the jugu lar vein (97 +/- 5 pg/ml, p < 0.001). These studies indicate that coun ter current transfer of estrone and androstenedione in the area of the ovarian artery on days 17-18 of the oestrus cycle of gilts elevates t he local concentration of steroids not only in the arterial blood supp lying the ovary, bur also in the blood supplying the oviduct and proxi mal to the ovary area of the uterus. The results also demonstrate that locally elevated concentrations of steroid hormones also occur in the follicular phase as has been demonstrated in the luteal phase of the oestrus cycle.