Transformation of (1,2-3H)aldosterone in the foetal and placental compartments of the guinea pig.
In vivo and in vitro transformation of labelled d-aldosterone (11beta, 21-dihydroxy-3,20-dioxo-4-pregnen-18-al) was studied in the foetal tissues and placenta of guinea pig (35-45 days of gestation). The principal metabolite found in all of these tissues was tetrahydroaldosterone (3alpha, 18,21-trihydroxy-20-oxo-5beta-pregnan-18-al). A large transformation into this metabolite was found in foetal liver (67-68%) and in the placenta (69-82%). Incubation of [3H]- or [14C]aldosterone with the isolated placenta also showed a large conversion to the tetrahydroderivative suggesting that the reductase(s) of ring A of aldosterone is present in this tissue. Most of the unmetabolized aldosterone and tetrahydroaldosterone was found in the unconjugated fraction. Very little of the radioactive material was present in the polar steroids extracted with n-butanol. Aldosterone and tetrahydroaldosterone were liberated from this fraction after enzymatic hydrolysis (beta-glucuronidase and sulphatase) or by solvolysis, suggesting that part of these conjugates is present in the foetal compartment as sulphate esters and glucuronides. Moreover, in this fraction a polar, unconjugated aldosterone metabolite with the characteristics of an acidic compound was detected.
D000450:Aldosterone / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*; D000818:Animals; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006168:Guinea Pigs; D006868:Hydrolysis; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D010084:Oxidation-Reduction; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy
D000450:Aldosterone