Effect of changes in sodium or potassium balance, and nephrectomy, on adrenal renin and aldosterone concentrations.

Abstract

An active form of renin was confirmed in the adrenal gland of rats. It had a molecular weight of 40,000, generated angiotensin I (AI) from natural renin substrate at pH 7.4, and was found at concentrations 30 to 60 times higher than plasma renin in rats on a normal diet. Changes in sodium diet induced changes in adrenal capsular renin concentration (high Na 2.21 +/- 0.34, normal Na 4.34 +/- 0.53, low Na 13.19 +/- 1.67 ng AI/mg protein/hr). A high potassium diet also increased adrenal capsular renin from 5.27 +/- 0.53 to 39.78 +/- 5.68 ng AI/mg protein/hr, while plasma renin concentration decreased from 7.28 +/- 0.63 in the normal diet to 5.05 +/- 0.60 on the high potassium diet. Neither diet altered the concentration of renin in the fasciculata-medullary portion of the adrenal gland. Nephrectomy markedly increased the renin concentration in the adrenal capsules without any effect on the decapsular cells (20 hours after nephrectomy, 71.5 +/- 10.6 ng AI/mg protein/hr). Sodium loading or dexamethasone treatment prior to nephrectomy blunted the rise in adrenal renin (nephrectomy + dexamethasone = 27.64 +/- 4.33 ng AI/mg protein/hr; nephrectomy + NaCl = 38.70 +/- 5.82 ng AI/mg protein/hr). In all experiments, there was a positive correlation between adrenal renin and adrenal aldosterone concentrations, but the experiments did not rule out the possibility that this positive correlation was due to two independent variables changing in the same direction and not causally related. In conclusion, adrenal renin may be a local hormone, involved in the regulation of aldosterone production.

Effect of Atrial Natriuretic Peptide on Adrenal Renin and Aldosterone.

“…However, the mechanism by which adrenal renin controls aldosterone release is unclear. The parallel changes in adrenal renin and adrenal aldosterone observed in the present experiments also support a previous investigation (Doi et al, 1984) which indicated adrenal renin as a possible mediator of aldosterone realease. Under ACTH stimulation, ANP suppressed the adrenal renin and adrenal aldosterone, whereas no changes in these substances were observed in rats receiving ANP withont ACTH.…”

“…However, similar changes in adrenal renin to adrenal aldosterone following ANP with and without ACTH were observed, so that the mechanisms by which ANP inhibits aldosterone release may involve suppression of the adrenal renin-angiotensin system. An increase in adrenal renin was demonstrated in nephrectomized rats (Doi et al, 1984, Inagami et al, 1984. In this condition, circulating angiotensin II must have been at an undetectable level.…”

“…Accumulated results of studies on adrenal renin have suggested that this enzyme is closely related to aldosterone release (Doi et al, 1984, Nakamura et al, 1985. However, the mechanism by which adrenal renin controls aldosterone release is unclear.…”

“…It is generally accepted that renin-like enzyme in the adrenal gland participates in the regulation of aldosterone production (Doi et al, 1984, Nakamura et al, 1985. Recently, the existence of intrinsic renin, angiotensin I, II and III was demonstrated in the adrenal gland (Nakamura et al, 1985) and the concept of this acting as a local modulating system for aldosterone production was emphasized.…”

“…On the other hand, after the existence of an inhibitor of aldosterone release was suggested in the dog atrium (Anderson et al, 1959), mammalian artrial granule peptide was detected (Currie et al, 1984) and studies on the inhibition of aldosterone production by this peptide were undertaken , Goodfriend et al, 1984. The peptide was originally shown to be a hormone with potent natriuretic, diuretic (Garcia et al, 1982, DeBoId et al, 1982 and vascular smooth muscle relaxant actions , Camago et al, 1984 The adrenal renin activity was measured in Tris acetate buffer, pH 7.4, using nephrectomized rat plasma as substrate following the method described previously (Doi et al, 1984). To estimate the adrenal renin activity, the generated angiotensin I was measured with a CEA-IRE-SORIN kit (France).…”