Aldosterone secretion during acute respiratory acidosis and NH₄CI‐induced metabolic acidosis in the goat

Acute respiratory acidosis was induced in goats by inhalation of 6% or 8% CO₂ in air for 30 min. The lower CO₂ concentration caused a significant rise in plasma Cortisol (PC), but had no appreciable influence upon plasma aldosterone (PA), and did not affect the arterial blood pressure (aBP). A more pronounced PC response was observed in association with the inhalation of 8% CO₂, but also here without concomitant increase in PA. However, the aBP became elevated by about 30% during the CO₂ exposure with a simultaneous increase in glomerular filtration rate and a water diuresis, suggesting that the release of arginine vasopressin temporarily became inhibited. It was confirmed that metabolic acidosis induced by duodenal NH₄Cl administration is preceded by a transient rise in PA. Dexamethasone‐induced feedback inhibition of the ACTH secretion blocked the PA response, which possibly reflects NH₄ ion stimulation of the ACTH release. The combined results of the CO₂ and NH₄Cl experiments seem to justify the conclusion that increases in PA seen in conjunction with acidosis do not reflect a direct hydrogen ion stimulation of the adrenal glomerulosa cells.