Prostaglandin metabolism in rabbit kidney. Identification and properties of a novel prostaglandin 9-hydroxydehydrogenase.

Prostaglandin F2alpha is metabolized in 100 000 X g supernatants of rabbit kidney by a 15-hydroxydehydrogenase and a delta13-reductase to F-series metabolites, and byt a 9-hydroxydehydrogenase to E-series compounds. The reactions were measured by radiochemical and biological assays. The 15-hydroxydehydrogenase and 9-hydroxydehydrogenase are localised specifically in renal cortex, have optimal activity at alkaline ph and are effective over a wide range of substrate concentrations. The 9-hydroxydehydrogenase oxidises the 9-alpha hydroxyl group of prostaglandin F2alpha and F1alpha but not the 9-beta hydroxyl group of prostaglandin F2beta. This enzyme is also found in rabbit stomach and ileum, but not in 8 other organs examined; the 15-hydroxydehydrogenase has a wider distribution. Unlike other 9-hydroxydehydrogenase enzymes described to date, the enzyme prepared from rabbit kidney converts prostaglandin F2alpha directly to E2 in substantial amounts; this conversion may be of importance in renal homeostasis.