Serum gamma-glutamyl transpeptidase activity in myocardial ischaemia.

The enzyme, y-glutamyl transpeptidase, cata- lyses the transfer of y-glutamyl groups from yglutamyl peptides to other peptides, L amino acids, and water. A high level of activity has been found in normal renal, pancreatic, pulmonary, and hepatic tissues (Goldbarg et al., 1960). High levels of this enzyme have been found in sera of patients with hepatic and pancreatic disorders (Rutenburg, Goldbarg, and Pineda, 1963) and in dia- betes mellitus (Goldbarg et al., 1963), but in the absence of disease affecting these organs Agostoni, Ideo, and Stabilini (1965) found high serum levels following myocardial infarction, with a peak on about the tenth day. This led us to study the be- haviour of this enzyme in the sera of a more com- prehensive group of patients with ischmmic heart disease. It was thought that changes in levels of this enzyme might help in distinguishing patients with myocardial infarction from those presenting similarly but showing no evidence of myocardial necrosis, as judged by the appearance of serial electrocardiograms and the observation of the serum activity of other enzymes whose place in the diagnosis of myocardial infarction is well established.