GUSTATORY-ALIMENTARY REFLEX INHIBITION OF ALDOSTERONE HYPERSECRETION BY THE AUTOTRANSPLANTED ADRENAL GLAND OF SODIUM DEFICIENT SHEEP

Abstract

ABSTRACT Several experimental investigators have reported that stimulation of gustatory and alimentary afferents may rapidly influence metabolic and endocrine processes. Changes may precede absorption of materials ingested and anticipate the physiological consequences. A colony of sheep with autotransplanted adrenal glands and a permanent unilateral parotid fistula, have been studied over a perior of 12 years. The effect on corticosteroid secretion of rapid satiation of salt appetite after 24–72 h of sodium depletion has been observed. The animals drank 300–900 mmol of NaHCO3 solution in 5–20 min. Rapid voluntary intake of NaHCO3 caused large evanescent reduction of aldosterone hypersecretion for the 15–36 min following satiation. Aldosterone secretion rebounded by 1 h towards control pre-drinking level. It then fell over 2–5 h to the Na+ replete range as a result of absorption from the gut of the sodium ingested. The satiation inhibition was seen in the majority, but not all sheep who had had a parotid fistula for several years. The effect was reproducible in the one animal over as long as six years. Analysis of the mechanism showed that it was not due to change of the four factors currently known to be implicated in control of aldosterone secretion viz. plasma [Na], [K], angiotension II and ACTH. The data indicates the action of an unidentified factor in the control of aldosterone secretion - possibly an inhibitor substance originating in the brain.