[Neutralization of ammonia in cardiac muscle].

The pathways of ammonia neutralization in the rat heart muscle were traced with nitrogen-15 isotope. The effect of ammonia concentration in the perfusate on its utilization by the myocardium was investigated over the range of 1.6--3.4 mM. Considerable amounts of the neutralized ammonia were found in glutamine and glutamic acid, less quantities in alanine and aspartic acid. Isoproterenol-induced necrosis of the heart muscle leads to a decrease in both glutamine and alanine ability to bind ammonia (20--40 and 30--45%, respectively). The necrosis effect is not significant for glutamic acid. In necrosis nitrogen-15 incorporation into aspartic acid declines whereas with higher concentrations it significantly increases.