Effect of Adrenalectomy on Production and Excretion of Ammonia by the Kidneys

¹ From the Department of Internal Medicine, The University of Texas Southwestern Medical School, Dallas, Texas

The rate and magnitude of ammonia excretion and renal glutaminase adaptation is normal in adrenalectomized rats given moderate (up to 4 mEq/day) amounts of NH₄Cl. The administration of large amounts of NH₄Cl (5 mEq/day or more) invariably kills adrenalectomized rats. Shortly before death, renal glutaminase adaptation was normal. Survival of adrenalectomized rats on large amounts of NH₄Cl could be prolonged if potassium was eliminated from the diet. Notwithstanding the prevention of hyperkalemia by restricting potassium intake and salt depletion by the provision of adequate amounts of sodium chloride, ammonia excretion is impaired in rats given large doses of NH₄Cl despite normal adaptation of renal glutaminase. It is suggested that adrenal steroids are not involved in either the maintenance or activation of the glutaminase enzyme system in the kidneys of rats. In adrenalectomized rats given large doses of NH₄Cl, the diminished excretion of ammonia appears to be a consequence of a diminished Na⁺–H⁺ exchange resulting from two disturbances: a) reduced delivery of Na⁺ to distal tubular exchange site, owing to peripheral circulatory insufficiency arising from salt depletion or potassium intoxication; b) a specific impairment of tubular reabsorption of Na⁺ owing to the absence of adrenal steroids.