Glycogen phosphorylase isoenzyme BB in diagnosis of myocardial ischaemic injury and infarction. Molecular and Cellular Biochemistry

l Summary: Glycogen phosphorylase isoenzyme BB mass release was studied in 20 patients undergoing coronary artery bypass grafting. In 16 patients with uneventful coronary arteiy bypass grafting, glycogen phosphorylase isoenzyme BB mass concentrations showed a significant, transient increase in the post cross-clamping period and: decreased to baseline values within 20 hours (peak concentrations ranged firom 12.7 g/l to 47.5 g/l, median 40! g/l). One patient did not fulfil criteria for perioperative myocardial infarction, but clinical data indicated myocardial l injury after aortic unclamping. In this patient only glycogen phosphorylase isoenzyme BB mass concentration and not creatine kinase isoenzyme MB catalytic concentration was increased, compared with uneventful patients. In 2 patients with emergency coronary artery bypass grafting for evolving myocardial infarction, glycogen phosphorylase isoenzyme BB mass concentrations, but not creatine kinase isoenzyme MB catalytic concentrations, correlated with clinical evidence of myocardial ischaemia. Our data indicate that glycogen phosphorylase isoenzyme BB mass concentration is a very sensitive laboratory marker of perioperative myocardial injury in patients undergoing coron-ary artery bypass grafting. Introduction study was to investigate glycogen phosphorylase isoen-K., t-, zyme BB release in patients undergoing coronary arteryGlycogen phosphorylase1) is the key enzyme of glyco-