Rapid detoxification of infused ammonium by the anesthetized rat

Anaesthetized rats were given an i.v. overload of 200 mmoles of ammonium acetate. Plasma ammonium levels were not altered for up to 20 minutes after the end of the infusion. The load of ammonium, however, increased the overall non-protein nitrogen content of circulating plasma, as for the increase in urea and amino acids (alanine, phenylalanine, aspartate + asparagine and glutamate + glutamine). The activities of glutamine synthetase was found increased in liver, muscle and kidney; and glutamate dehydrogenase increased in liver and decreased in muscle and kidney. Adenylate deaminase decreased in all the studied tissues. The fast enzyme and plasma metabolite adaptations to ammonium overload were all in the sense of favoring the incorporation of ammonium into amino acids (later into urea) as well as to avoid their deamination, thus effectively removing the excess ammonium from the bloodstream.