Ammonia intoxication and its effects on brain and blood ammonia levels

Abstract

Since the evidence for a relationship between convulsive disorders and brain and blood ammonia content was not conclusive, the changes in brain ammonia levels were compared with those occurring in the blood after acute ammonia intoxication, produced in rats by intraperitoneal injection of ammonium acetate in LD 50 dose. Blood and brain ammonia estimations were performed on the survivors at 5 min intervals from 5 to 60 min after the injection. An unusual time-course of ammonia content with two peaks at 5 and 20 min after the injection of the toxic agent was found in the blood, whereas in the brain an increase in ammonia was observed until 25 min after intoxication. The level of ammonia then remained approximately unchanged until 50 min, after which a slow decrease was observed. Hyperexcitability and convulsions occurred in the rats in the first 20–25 min, while lethargy and coma were observed later. These results together with those obtained by other authors point to the possible existence of a biphasic action of ammonia on the central nervous system. The mechanism of action is discussed.