Metabolism and toxicity of ammonia.

THE recent and continuing interest in the possible toxic effects of ammonia in diseases of the liver and portal circulation has led to this progress report, which must of necessity begin with the origin of the problem. Ammonia is a highly toxic substance, and since it is a by-product of various phases of protein metabolism, mechanisms are required for its detoxification and disposal. In vertebrates existing in a water environment, this problem is handled very easily by a simple diffusion of ammonia into the surrounding fluid environment. The adaptation to a terrestrial environment, however, requires the conversion to a nontoxic . . .