Adaptations in metabolic acidosis: a reinterpretation.

Hydrochloric-acid induced acidosis reduced urea excretion in the rat, with an equimolar increase in NH+4 excreation and no change in their sum. By contrast, in the guinea pig, where ammonium excretion is small, HC1 administration did not effect urea excretion. Ammonium administered as NH4HCO3 was excreted mainly in the form of urinary urea, whereas that administered as NH4C1 was mainly in the form of ammonium. Methionine sulphoximine did not impair the increased ammonium excretion induced by acidosis, but did lead to a marked decrease in plasma glutamine levels and an overall increase in total urinary urea and ammonium nitrogen excretion. A reinterpretation of some aspects of the adaptations to metabolic acidosis is made based on these findings.