Abstract
Summary
Prostaglandins F (PGF) were measured in uterine vein, ovarian artery, and jugular vein plasma and in the endo-metrial tissues at various times during the bovine estrous cycle, and were compared to peripheral plasma progesterone levels. Four groups of heifers at days 1-5, 10-14, 15-17 and 20-0 of the estrous cycle were studied. Low levels of PGF (48 ± 12 ng/g dry tissue were measured in the endometrium on days 1-14 of the cycle. Higher values (131 ± 9.0) were found at days 15 until the day of estrus (P < 0.001). Similarly, very low levels of PGF were observed in the uterine vein plasma at days 1-14 (0.162 ± 0.044) ng/ml M ± S.E.), whereas on days 15 until the day of estrus the levels ranged from 1.5 to 3.0 ng/ml. The increases in uterine vein PGF on day 15 occured even while peripheral plasma progesterone levels were still high. However, PGF was not elevated in either the ovarian artery or the jugular vein at any time during the cycle, even when uterine vein levels were greatly elevated. No differences in PGF content were detected in endometrial tissue from uterine horns adjacent or opposite to the functional corpus luteum.
We thank Dr. J. E. Pike of The Upjohn Company for the gift of prostaglandins used as standards in the radioimmunoassay, and Dr. K. Kirton of The Upjohn Company for supplying PGF antisera. We are grateful to D Lensing for skillful technical assistance.
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