The synthesis of reduced metabolites of aldosterone by subcellular fractions of rat kidney: effects of antimineralocorticoids.
Subcellular fractionation of male rat kidney revealed that the nuclear and plasma membrane fractions isolated from the 1,000 g pellet retained a significant proportion of the aldosterone ring-A reducing activity. Improved HPLC solvent systems separated all six possible ring-A reduced metabolites of aldosterone and revealed that 80-90% of the reduced metabolites synthesized by purified nuclei and plasma membranes were 5 alpha-reduced compounds consisting of 5 alpha-DHA and 3 alpha,5 alpha-THA in ratios of 1:2 (nuclei) and 1:1 (membranes). The 105,000 g cytosol also synthesized significant quantities of reduced, hydroxylated, and conjugated metabolites of aldosterone. In contrast, the majority of the reduced metabolites of aldosterone synthesized by kidney cytosol were 5 beta-products, consisting principally of 5 beta-DHA and smaller quantities of 3 alpha,5 beta-THA and 3 beta,5 beta-THA. The synthesis of reduced aldosterone metabolites in the cytosol, nuclear, and plasma membrane fraction was inhibited by both 5 and 50 microM concentrations of the antimineralocorticoids, progesterone, K+-canrenoate, and corticosterone. Progesterone was the strongest inhibitor of the synthesis of 5 alpha-DHA and 3 alpha,5 alpha-THA in both nuclei and plasma membranes. The overall order of inhibition of the synthesis of ring-A reduced metabolites in the kidney subcellular fractions was progesterone greater than K+-canrenoate greater than corticosterone; both progesterone and K+-canrenoate inhibited 5 alpha-reduction more than 5 beta-reduction.
D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D002191:Canrenoic Acid / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003345:Corticosterone / Q000494:pharmacology; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008901:Mineralocorticoids / Q000037:antagonists & inhibitors*; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D008901:Mineralocorticoids; D000450:Aldosterone; D011374:Progesterone; D002191:Canrenoic Acid; D003345:Corticosterone