Mineralocorticoid receptors along the nephron: (/sup 3/H)aldosterone binding in rabbit tubules

Journal Article · Tue Dec 01 04:00:00 EST 1981 · Am. J. Physiol.; (United States)

OSTI ID:5655901

Doucet, A; Katz, A I

To identify the site of mineralocorticoid action along the nephron, we measured the specific binding of (/sup 3/H)aldosterone to nephron segments microdissected from aldosterone-deficient rabbits. Specific binding was defined as the difference between binding measured in the absence or in the presence of 2,000-fold excess of unlabeled hormone (in 10/sup -18/ mol.cm tubule length/sup -1/ +/- SE). High specific binding capacity was found in the branched collecting tubule (108 +/- 4), the cortical collecting tubule (119 +/- 9), and the outer medullary collecting tubule (115 +/- 16), whereas specific binding was negligible in the proximal convoluted tubule (8 +/- 9), pars recta (2 +/- 6), medullary thick ascending limb (4 +/- 6), cortical thick ascending limb (6 +/- 2), and distal convoluted tubule (6 +/- 6). In cortical collecting tubules, Scatchard analysis of the specific (/sup 3/H)aldosterone binding indicated a dissociation constant (K/sub D/) of 2.2 X 10/sup -9/ and a maximum number of binding sites of 157 X 10/sup -18/ mol.cm tubule length/sup -1/. The steroid specificity was assessed from the competition of various steroids for (/sup 3/H)aldosterone binding sites. Receptors from the cortical collecting tubule revealed the following sequence of affinities: aldosterone > DOCA > spironolactone > dexamethasone > 5..cap alpha..-dihydrotestosterone = progesterone = 17..beta..-estradiol, indicating that the binding sites in the collecting tubule are mineralocorticoid receptors. These results demonstrate significant (/sup 3/H)aldosterone binding to receptors of high affinity and mineralocorticoid specificity only in the collecting tubule and suggest that this nephron segment is the target site of mineralocorticoid action in the rabbit kidney.

• Research Organization: Univ. of Chicago, IL
• OSTI ID: 5655901
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 241:6; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ALDEHYDES
ALDOSTERONE
ANIMALS
BIOCHEMISTRY
BODY
CHEMISTRY
CORTICOSTEROIDS
HORMONES
HYDROXY COMPOUNDS
KETONES
KIDNEYS
LABELLED COMPOUNDS
MAMMALS
MINERALOCORTICOIDS
ORGANIC COMPOUNDS
ORGANS
PREGNANES
RABBITS
RECEPTORS
STEROID HORMONES
STEROIDS
TRITIUM COMPOUNDS
TUBULES
VERTEBRATES