Effects of ammonia on synaptosomal membranes.

Acute and sustained hyperammonemia in mice resulted in a decrease of the transition temperature of Arrhenium plots of synaptosomal (Na+-K+)ATPase. The activation energies in both phases of the plots were increased. "In vitro" addition of ammonia produced similar changes. This seems to indicate that ammonia alters the physical properties of synaptosomal membranes. The "in vitro" interaction of ammonia and ethanol at the membrane level was also investigated. Both agents together produced a further shift in the transition temperature and affected the activation energies. The relevance of these findings regarding the mechanism of ammonia toxicity and the protective effect of ethanol thereon is discussed.