Further Studies on the Secretion of Aldosterone by the Rat Adrenal Gland

Abstract

1. In rats fed normal diets, the intravenous, subcutaneous or intraperitoneal administration of potassium chloride, either immediately or at graded intervals before the collection of adrenal vein blood, did not increase the secretion of aldosterone. In animals fed low salt diets, excess of dietary potassium did not result in an increase in the secretion of aldosterone.2. Chloride deficiency in the diet, for a period of 2 weeks, did not affect the rate of aldosterone production.3. The intravenous administration of hypertonic saline just prior to collection of adrenal vein blood did not affect the rate of aldosterone secretion, but substitution of saline for drinking water for a period of 1 week reduced it.4. Production of metabolic acidosis resulted in increased secretion of aldosterone. Production of metabolic alkalosis did not affect it. It is concluded from these results that altering the intracellular electrolyte composition of skeletal muscle will not affect the secretion of aldosterone. 5. Removal of peripheral blood either 2 hr, or 26 + 2 hr, before collection of adrenal vein blood in animals fed normal or low salt diets did not influence the secretion of aldosterone.Neither did maintaining the blood volume, with freshly drawn rat blood, during the collection of adrenal vein blood. 6. It was not possible to prevent the release of ACTH associated with the collection of adrenal vein blood by the use of morphine.The role played by aldosterone in salt and water metabolism and the factors which affect its rate of secretion continue to be of interest to physiologists. The relative independence of the secretion of this hormone from adrenocorticotrophic hormone

Comparison of Effects of Prolonged Aldosterone Administration on Rat Colon and Renal Electrolyte Excretion

“…Thus, in a group of five rats, the rate of Na+ excretion at night was 61 + 5 /tmol/h and during the day was 10 + 7 /¿mol/h. The normal endogenous aldosterone secretion rate is about 1-0/¿g/h for a 300 g rat (Singer, 1959) while in the present experiments aldosterone was administered at a constant rate ten times that of the endogenous rate. The fact that diurnal variation persisted despite this high constant rate of aldosterone administration makes it unlikely that under normal circumstances diurnal variation of Na+ excretion is a consequence of changes in the rate of endogenous aldosterone secretion.…”

Aldosterone and Renal Potassium Excretion

“…Normal 0.6-1.3 ng/min, aortic constriction 1.7 ng/min [28]. 1 /zg/h [80]. Sheep, sodium excess 1 /zg/h, sodium deficient 11 //g/h [13).…”

Effect of Sodium Restriction and Experimental Nephrosis on Tissue Spaces and Tissue Sodium Distribution in the Rat

“…The normal diet fed was diet 86 (North Eastern Agricultural Co-Op., Aberdeen). The aldosterone secretion rate in rats fed this diet was the same as in those fed a synthetic diet containing 0-3 % NaCl (Singer, 1960). The low sodium diet was prepared according to Cotlove, Holliday, Schwartz & Wallace (1951).…”

“…The tissues to be investigated were removed as quickly as possible, blotted free of blood and weighed on a torsion balance. The average sample weight was 50 mg. except in the case of abdominal muscle where it was 150 mg. Adrenal vein blood was obtained by cannulation of the vein as described by Singer (1960).…”

“…Rats rendered nephrotic by the administration of an aminonucleoside related to Puromycin have an increased secretion of this hormone (Singer, 1957). The present study was undertaken to discover whether changes in the distribution of water and sodium occurred in the presence of increased secretion of aldosterone.…”