Radioenzymaticassay for some substrates and inhibitors of human placental 11-hydroxysteroid dehydrogenase.
A radioenzymaticassay (REA) is described, using labelled cortisol and a homogenate of human placenta. Steroids which are able to compete with the tracer for conversion to the 11-keto form can be measured. Of these, 11 beta and 11 alpha-hydroxyprogesterone (11 beta-hydroxypregn-4-ene-3, 20-dione), 3 beta, 11 beta-dihydroxypregn-5-ene-20-one, 11 beta, 20 alpha-dihydroxypregn-4-ene-3-one and corticosterone are the most active, while cortisol and prednisolone are moderately active. All other steroids tested competed less than 10% as effectively as 11 beta-hydroxyprogesterone at 50% conversion with no added substrate. The sensitivity was 0.8 ng of 11 beta-hydroxyprogesterone and 5 ng cortisol. Using this REA, preliminary studies were carried out to investigate the endogenous substrates and inhibitors of 11-hydroxysteroid dehydrogenase in human fetal tissues.
D000302:Adrenal Cortex; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005333:Fetus; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D006908:Hydroxyprogesterones / Q000032:analysis; D006913:Hydroxysteroid Dehydrogenases / Q000032:analysis*; D007124:Immunoenzyme Techniques; D008099:Liver; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D000091402:Prohibitins; D011863:Radioimmunoassay / Q000379:methods; D014021:Tissue Preservation
D006908:Hydroxyprogesterones; C000717331:PHB2 protein, human; D000091402:Prohibitins; C030228:11-hydroxyprogesterone; D006913:Hydroxysteroid Dehydrogenases; D006854:Hydrocortisone