A comparison of arachidonic acid metabolism by microsomes from pregnant rat decidua and myometrium.

Microsomes were prepared from scraped decidua and myometrium of rat uteri on day 22 of pregnancy. When incubated with [1-14C] arachidonic acid decidual microsomes produced predominantly prostaglandin E2 with smaller quantities of prostaglandin F2 alpha, 6-oxo-prostaglandin F1 alpha, prostaglandin D2 and thromboxane B2. The major product from the incubation of the myometrial microsomes was 6-oxo-prostaglandin F1 alpha, with a small quantity of porstaglandin E2. Incubation conditions for the decidual and myometrial microsomes were characterized with respect to pH, incubation time, substrate, and co-factor concentrations for optimal prostaglandin biosynthesis. Biosynthesis was stimulated by reduced glutathione without altering the proportions of products synthesised. Hydroquinone was found to be essential for prostaglandin formation. The ability of several biogenic amines to substitute as co-factors for hydroquinone was investigated. There are major differences in the optimal incubation conditions for uterine microsomes and prostaglandin synthetase preparations from other tissues.