Effect of myocardial ischaemia-reperfusion on granulocyte elastase release

During extracorporeal circulation, activation and degranulation of neutrophil granulocytes occur, with subsequent massive release of elastase, a neutral protease stored in the azurophil granules. Neutrophil granulocytes and oxygen-derived free radicals are intimately involved in the occurrence of reperfusion injury, which affects especially the lungs and the myocardium. In this study we evaluated changes in the leucocyte count and of the plasma elastase levels in the coronary circulation during open heart surgery. We collected blood samples from the radial artery and the coronary sinus before skin incision, after onset of cardiopulmonary bypass and 5, 15, 30, 60, 120 minutes after the release of the aortic cross-clamp. The leucocyte count did not change significantly during the operation and no difference in leucocyte count was found between the radial artery and the coronary sinus. Plasma elastase levels significantly increased after the onset of cardiopulmonary bypass (P = 0.007) and after the release of the aortic cross-clamp (P = 0.001). Moreover, significantly higher values were found in the coronary sinus than in the radial artery 5 (P = 0.04), 15 (P = 0.02) and 30 (P = 0.02) minutes after the release of the aortic cross-clamp. We assume, therefore, that during the early phase of reperfusion, degranulation of neutrophil granulocytes occurs in the coronary circulation.