Relation of glutamate to ammonia production in the rat kidney

Abstract

Glutamate was an effective inhibitor of isolated rat renal glutaminase at concentrations normally found in the kidney. Injection of monosodium glutamate into acidotic rats inhibited renal ammonia excretion about 50% with no significant effect on urinary pH. Alterations in acid-base balance known to increase (metabolic acidosis) and decrease (metabolic alkalosis) renal ammonia production caused significant changes in renal glutamate concentrations. Metabolic acidosis (40 mmoles NH4Cl/kg per day) produced a rapid (1 day) and sustained (3 days) decrease (35%) in glutamate concentrations. Injection of acetazolamide (300 mg/kg per day) reduced glutamate concentration 20% within 3 days. Metabolic alkalosis (40 mmoles NaHCO3/kg per day) produced a gradual increase (25%) in glutamate concentration over a period of 3 days. These results suggest that glutamate may play a role in the regulation of renal ammonia production.