Rate of Ovarian Progesterone Secretion in the Dog

Abstract

The average rate of progesterone secretion into the ovarian vein blood of anaestrus dogs under pentobarbital anesthesia, 0.71 μg/ovary/min (range 0.33–1.20), did not significantly change over a 4-hour period following a single I.V. injection of 1000 units of human chorionic gonadotrophin (HCG). I.M. administration of HCG or horse pituitary gonadotrophin twice daily for 3 days to 2 animals increased the progesterone secretion rate to 2.16 and 3.11 μg/ovary/min or to an average of 3.8 mg/ovary/24 hrs. There tends to be a significant relation between progesterone secretion rates and ovarian blood flow rates. Plasma progesterone concentrations do not necessarily reflect ovarian secretion rates because progesterone concentration is relatively dependent on blood flow rates. Progesterone was found in very small amount or not at all in vein blood from ovaries without corpus luteum tissue.