title: Formation of 6-keto prostaglandin E1 in mammalian kidneys.
abstract: 1 The metabolism of prostacyclin (PGI2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) was studied in cell-free homogenates of rat, rabbit and guinea-pig kidney. 2 Rabbit kidney converted both PGI2 and 6-keto PGF1 alpha to a stable metabolite with chromatographic and biological activity identical to that of authentic 6-keto PGE1. Activity was found in the kidney cortex but not medulla, was inhibited by NAD+ or NADP+ (5 mM) and showed an optimum temperature requirement of 37 degrees C. 3 Guinea-pig kidney converted PGI2 but not 6-keto PGF1 alpha to a labile, biologically active metabolite which was not 6-keto pge1. 4 No conversion of prostacyclin or 6-keto PGF1 alpha to biologically active metabolites occurred in cell-free homogenates of rat kidney, liver and colon or guinea-pig liver and colon. 5 6-keto PGE1 rapidly lost spasmogenic activity on the rat stomach strip following incubation with rabbit or guinea-pig kidney supernatant in the absence of added cofactors. No loss of activity occurred on incubation with rat kidney. 6 Rutin (50 microM) potently inhibited synthesis of 6-keto PGE1 from added PGI2 by rabbit kidney cortex. This reaction was potentiated by a similar concentration of sulphasalazine, carbenoxolone, imidazole, papaverine or indomethacin. 7 The relevance of these findings for the possible physiological and pathological roles of 6-keto PGE1 in the kidney is discussed.
mesh_terms: D000527:Alprostadil / Q000031:analogs & derivatives*; D000818:Animals; D011464:Epoprostenol / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011458:Prostaglandins E / Q000096:biosynthesis* / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity; D013997:Time Factors
chemical_list: D011458:Prostaglandins E; C022950:6-ketoprostaglandin E1; D011464:Epoprostenol; D000527:Alprostadil