Myocardial glycolytic and gluconeogenic enzyme activity during cardiopulmonary bypass in humans

Through a study of the activity of the regulatory enzyme of glycolysis phosphofructokinase and the regulatory enzyme of gluconeogenesis fructose-1,6-diphosphatase, myocardial metabolism has been evaluated in the human heart during cardiopulmonary bypass. Three ventricular transmural biopsy specimens were obtained at open-heart surgery before cardiopulmonary bypass was instituted and three similar specimens were taken 30 minutes after cardiopulmonary bypass was started. The enzyme assays were performed on the supernatant obtained from myocardial cells disrupted by sonication. The activity of both enzymes increased during the anoxic conditions of cardiopulmonary arrest. The increase in phosphofructokinase activity is likely due to an overall increase in glycolytic activity, but the presence and increased activity of fructose-1,6-diphosphatase was unexpected.