Stimulatory Effect of Intraportal Ammonia on Plasma Uric Acid Concentration and Urinary Uric Acid Excretion in Chickens Fed a Low Protein Diet

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Abstract
To examine the effect of intraportal nitrogenous compounds on plasma uric acid concentration and urinary uric acid excretion, ammonium acetate, glutamine, asparagine and inosine were intraportally infused into the chicken fed a 5% protein diet. Ammonium acetate infusion at the rate of 0.05 mmole/kg body weight/minute caused significant increases in both plasma and urinary uric acid levels. Infusion of 0.025 mmoles ammonium acetate did not appreciably increase uric acid concentrations in the blood plasma and urine. Ammonium acetate infusion at 0.1 mmole significantly increased plasma and urinary uric acid levels, but another infusion of ammonium acetate at the same rate did not increase significantly plasma uric acid level (urinary uric acid not measured). The infusion of glutamine and asparagine at 0.1 mmole and of inosine at 16.6 µmole resulted in a significant increase in plasma uric acid level and no increase in urinary uric acid (inosine not tested). Glutamine infusion at 0.05 mmole did not have any effect on plasma and urinary uric acid levels. Increases in hepatic glutamine, and blood and hepatic ammonia levels were the largest with ammonium acetate infusion at 0.1 mmole. Infusion of ammonium acetate at 0.05 mmole had the same effect on hepatic ammonia and glutamine levels as glutamine infusion at 0.05 mmole. However, plasma glutamine increased less when ammonium acetate at 0.1 mmole than when glutamine at 0.05 mmole was infused. This experiment indicates that the increased ammonia in the portal blood caused remarkable increases in plasma and urinary uric acid levels, and also marked increases in plasma and hepatic glutamine contents in the chicken fed the 5% protein diet.