title: Effect of adrenalectomy and aldosterone on the modulation of mineralocorticoid receptors in rat kidney.
abstract: Adrenalectomized rat kidney is commonly used for the study of mineralocorticoid mechanism of action in mammals. In this model, aldosterone is known to bind to two classes of binding sites: type I (mineralocorticoid) and type II (glucocorticoid). The study of the aldosterone binding in normal rat kidney requires the elimination of endogenous hormones bound to each type of receptor. Thus, a suitable technique was developed using in situ perfusion of the kidneys. The efficacy of this method was of about 85 to 90% at the level of both cytoplasm and nucleus. Aldosterone binding capacity was checked in normal rat kidney after in situ perfusion and was found to be 300 to 500% lower than in adrenalectomized rat kidney, both in cytoplasm and nuclei. Computer analysis of aldosterone binding parameters in the cytoplasm (30,000 X g supernatant) of rat kidney suggested that adrenalectomy might induce an important rise in the number of mineralocorticoid receptors (congruent to 260%). An increase in the number of glucocorticoid receptors was also observed but appeared to be lower. Aldosterone, when perfused during 24 h in adrenalectomized rats, lowered the number of type I sites to the same level as observed in normal rat kidney. This effect was fully reversible after interruption of aldosterone perfusion. These results suggested an aldosterone-induced down regulation of mineralocorticoid receptors.
mesh_terms: D000315:Adrenalectomy; D000450:Aldosterone / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010477:Perfusion; D051381:Rats; D018161:Receptors, Mineralocorticoid; D011987:Receptors, Steroid / Q000187:drug effects / Q000378:metabolism*
chemical_list: D018161:Receptors, Mineralocorticoid; D011987:Receptors, Steroid; D000450:Aldosterone