1. The effects of intestinal ammonia in uraemia have been studied by administering a urease inhibitor, acetohydroxamic acid, to bilaterally nephrectomized rats.
2. Ammonia concentration was significantly decreased in the colon although it remained slightly higher than in normal animals. Caecal ammonia concentration was not altered. Total ammonia content was decreased in both colon and caecum.
3. A study in vitro indicated that ammonia production could be totally inhibited by acetohydroxamic acid. This suggests that the failure to suppress ammonia production in vivo is due to failure of the inhibitor to reach the site of urease production in sufficient concentration.
4. The animals treated with high doses of acetohydroxamic acid survived for a shorter time. Blood urea was higher and total serum protein lower in the treated group. The incidence of colitis was not affected.