Comparison of intrauterine prostaglandin metabolism during pregnancy in man, sheep and guinea pig.

Metabolism of prostaglandin F2 alpha (PGF2 alpha) was studied in uterine tissues from pregnant women (n = 10), sheep (n = 6) and guinea pigs (n = 6). Two maternal tissues, myometrium and decidua or maternal placenta, and two fetal tissues, fetal placenta and membranes, were studied in each species. PGF2 alpha was metabolized via the well-known pathway into 15-keto-PGF2 alpha and 13,14-dihydro-15-keto-PGF2 alpha, while 13,14-dihydro-PGF2 alpha was tentatively identified in some tissues. The presence of 15-hydroxyprostaglandin dehydrogenase (PGDH) and 13,14-prostaglandin reductase was demonstrated in all tissues from each of the three species studied, but the quantitative intrauterine distribution of these enzymes differed from one species to another. In man, PGDH activities were highest in fetal membranes followed by fetal placenta and then by decidua and myometrium. In sheep, PGDH activities were highest in the maternal placenta followed in decreasing order by myometrium, fetal placenta and membranes. In the guinea pig, PGDH activity was highest in the fetal membranes followed in decreasing order by maternal placenta, fetal placenta and myometrium. Quantitative assay of PGDH showed that PGDH activity in the pregnant uterus is higher in women than in sheep and guinea pig. The results are discussed in relation to the involvement of prostaglandins in parturition.