Hyperaldosteronism in the sodium depleted rat: effect of a low sodium diet or diuretic treatment on steroid output by the superfused adrenal zona glomerulosa.

ABSTRACT

The effect of chronic and acute sodium depletion on the function of the adrenal zona glomerulosa was examined by means of superfusion of adrenal capsular glands. The glands were removed from rats kept on a low sodium diet for 7 days or from dexamethasone-pretreated rats 30 min after administration of the diuretic drug furosemide. Chronic sodium depletion brought about a high initial output of aldosterone followed by a rapid fall in output. The initial rate of corticosterone output did not differ significantly from that by control glands but exhibited a more rapid decline with time. Aldosterone corticosterone ratio, an indicator of the rate of conversion of corticosterone to aldosterone, was much higher in the sodium depleted group throughout the whole superfusion period. Acute sodium depletion was followed by high initial and rapidly falling aldosterone and corticosterone output, without any significant change in the ratio of aldosterone to corticosterone output rate. The above dynamic patterns of steroid output indicate that a sodium deficient diet evokes hyperaldosteronism by increasing the formation of aldosterone from corticosterone (not excluding the possibility of increasing the formation of corticosterone as well) while diuretic treatment stimulates aldosterone secretion by acting on the formation of corticosterone only.