The metabolism of prostaglandins by the guinea-pig uterus with particular reference to corpus luteal maintenance in early pregnancy.

1 Homogenized lung tissue from day 15, pregnant and non-pregnant guinea-pig metabolized exogenous prostaglandin E2 (PGE2) and prostaglandin F2alpha (PGF2alpha) almost completely when incubated in Tyrode solution containing beta-nicotinamide adenine dinucleotide (NAD+). 2 Metabolism of PGE2 and PGF2alpha by homogenates of day 15, pregnant or non-pregnant, guinea-pig uteri was relatively low (8 to 20%) when incubated in Tyrode solution containing NAD+. 3 Day 15, guinea-pig conceptuses (placentae and embryos), homogenized and incubated in Tyrode solution containing NAD+, metabolized prostaglandins to a slightly greater extent (14 to 22%) than day 15, uterine tissue. 4 Addition of exogenous arachidonic acid to day 12 or day 15, pregnant, guinea-pig uterine homogenates in Tyrode solution did not increase the yield of PGF2alpha following incubation. 5 It is concluded that neither an increase in metabolism of PGF2alpha by the uterus and conceptus nor lack of precursor is responsible for the lower secretion of PGF2alpha from the day 15, pregnant, guinea-pig uterus when compared to the day 15, non-pregnant uterus.