title: Ontogeny of renal mineralocorticoid receptors and urinary electrolyte responses in the rat.
abstract: We examined the ontogeny of cytosol mineralocorticoid receptors in renal inner medulla-papilla (IM-PAP) and outer medulla-cortex (OM-CX) and of a biological response to administered corticosteroids (urinary K+/Na+ ratio). Rats at early (7-9 days), intermediate (13-15 days), and late (23-30 days) stages of maturation were used. Young rats were found to be essentially insensitive to aldosterone, in contrast to rats aged 13-15 days and older. Scatchard analysis of IM-PAP and OM-CX cytosol showed equivalent high-affinity aldosterone binding sites at all ages. The affinity of these sites was constant (Kd, 4 degrees C approximately 0.5 nM) and their concentration varied only slightly over maturation. In a series of in vivo nuclear transfer studies, the hyposensitivity to aldosterone in young rats did not seem to be due to a difference in the nuclear binding of aldosterone-receptor complexes. The resistance of the immature (7-9 days) rat kidney to aldosterone thus appears to be a postreceptor phenomenon. The maturational events allowing expression of mineralocorticoid-inducible genes in the kidney remain to be determined.
mesh_terms: D000315:Adrenalectomy; D000375:Aging; D000450:Aldosterone / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D003345:Corticosterone / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005260:Female; D007668:Kidney / Q000254:growth & development*; D007672:Kidney Cortex / Q000254:growth & development; D007679:Kidney Medulla / Q000254:growth & development; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000652:urine*; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000502:physiology*; D011987:Receptors, Steroid / Q000502:physiology*; D012964:Sodium / Q000652:urine*
chemical_list: D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D000450:Aldosterone; D012964:Sodium; D011188:Potassium; D003345:Corticosterone