Secretion rate of prostaglandin F during induced labor in goats

Relationships between plasma flow and plasma concentrations of prostaglandin F were examined in the utero-ovarian veins of three pregnant goats. Plasma flow, measured by veno-arterial dilution of para-Aminohippurate in two goats, was unchanged or increased slightly when PGF concentrations were elevated by short-term infusions of PGF_2α into a uterine vein. Utero-ovarian plasma flow was measured during labor in two goats. Flow doubled during advanced labor and then decreased sharply to very low rates during the terminal expulsive phase of stage II labor.A total of 8.3 and 9.5 mg PGF was released into the utero-ovarian vein of two goats during the last 6 hours before fetal delivery and maximal release rates of approximately 100 ug. min⁻¹ were obtained some 5–10 minutes before delivery was completed. The highest plasma concentrations of PGF were detected immediately after completion of fetal delivery when utero-ovarian plasma flows were lowest.