Stereospecific Nuclear and Cytosol Aldosterone-Binding Proteins of Various Tissues

Abstract

³H-Aldosterone-binding proteins (ABP) were isolated from nuclear fractions of rat kidney, duodenal mucosa, spleen, liver and brain by extraction in Tris-CaCI₂ and precipitation in 50% (NH₄)₂SO₄. Cytosol (105,000 × g supernatants) ABP were isolated from the same tissues by G-50 Sephadex chromatography. The ABP content of the nuclear fractions was in the order: kidney ≈duodenal mucosa > spleen ≈liver≈ brain (table I). The ABP content of the cytosol fractions was in the order: kidney≈duodenal mucosa > spleen ≈ brain≈liver (table III). The relative affinities of the competing steroids, cold d-aldosterone, 9α-fluorocortisol, 17-isoaldosterone and 17/S-estradiol for the ³H-aldosterone binding sites were similar in both the nuclear and cytosol fractions of kidney, duodenal mucosa, spleen and liver. The active mineralocorticoids competed successfully for the ³H-aldosterone binding sites but the inactive steroids were either without effect or tended to enhance the binding of ³H-aldosterone. The physiological significance of relatively low levels of stereospecific ABP in spleen, liver and brain remains to be elucidated.

Comparative Studies on the Mineralo-Corticoid Action of Aldosterone and Carbenoxolone Sodium in the Adrenalectomized Rat

“…As an alternative way of expressing the effect of the various experimental manipulations on urinary electrolyte excretion, data were tabulated after the manner of Swaneck et al (1969). This method employs a comparison of the change in the urinary Na+:K+ ratio.…”

“…Analysis of the urinary electrolyte excretion data by either of the two methods (Fimognari et al, 1967;Swaneck et al, 1969), designed as sensitive techniques for the evaluation of mineralo-corticoid effects (electrolyte excre tion), failed to demonstrate any enhancement of the mineralo-corticoid action of aldosterone by carbenoxolone sodium.…”

Renal Pharmacology, with Special Emphasis on Aldosterone and Angiotensin

“…ABP were isolated not only from the kidney, but also from other tissues (140). High nuclear-and cytosol-binding activities were obtained in the duodenal mucosa, whereas the cytosol fractions of spleen, liver, and brain showed only little aldosterone-binding activity.…”

“…High nuclear-and cytosol-binding activities were obtained in the duodenal mucosa, whereas the cytosol fractions of spleen, liver, and brain showed only little aldosterone-binding activity. However, the nuclear fraction of the spleen contained approximately 40 % of the binding activity of the kidney, and also in the nuclear fractions of liver and brain some binding was observed (139,140). The significance of nuclear aldosterone binding in tissues in which the hormone has little, if any, effect on sodium transport remains unclear.…”

Presence of aldosterone-like immunoreactivity in cerebrospinal fluid in normotensive subjects

“…High-affinity, lowcapacity binding sites for aldosterone have been reported in a variety of tissues, including both classical epithelial target tissues (kidney, gut, and salivary gland (2)(3)(4)) and classical non-target tissues (spleen and liver (5,6)). …”