Failure of sodium benzoate to alleviate plasma and liver ammonia in rats.

The intraperitoneal administration of L-norvaline and L-methionine-SR-sulfoximine to rats caused an increase in the concentration of ammonia in plasma as well as in liver. These compounds interfere with urea and glutamine formation, respectively. Subsequent injection of sodium benzoate failed to alleviate ammonia levels, and on the contrary, caused a further increase. Sodium benzoate itself, when administered, resulted in higher levels of ammonia in plasma and liver of the rats. Administration of glycine to rats treated with benzoate did not lower ammonia levels indicating that other factors besides glycine may also be necessary for the removal of sodium benzoate.