[Mechanisms of ammonia binding in the heart muscle].

Kinetics of 15N inclusion into amino acids and urea of the intact isolates rat heart and of the rat heart with experimental infarction in the course of 1.6 mM 15N-ammonium acetate perfusion was investigated. The basic mechanism of ammonia binding in the heart is the glutaminsynthetase reaction. 15N inclusion into the glutaminic and asparaginic acids, alanine and urea takes place at a lower rate. In myocardial infarction 15N accumulation by all amino acids is slowed down and its accumulation by the urea is increased. The results suggest that urea synthesis activation in infarcted myocardium is a compensatory change brought about by a disturbance of basic mechanisms of free ammonia binding.