Background: Leukocytes are associated with myocardial injury during reperfusion after ischemia. Short periods of leukocyte depletion during reperfusion result in persistent attenuation of postischemic myocardial dysfunction.
Methods: Leukocyte depletion was examined in a canine model of regional myocardial ischemia and reperfusion. The extracorporeal circuit and cardioplegia circuits underwent leukocyte depletion by mechanical filtration. Animals were instrumented for baseline global function before 90-minute occlusion of the left anterior descending coronary artery. Global function during ischemia and at 5, 30, 60, and 90 minutes after a 60-minute cardioplegic arrest using continuous blood cardioplegia was assessed in leukocyte-depleted (n = 9) and control (n = 10) groups.
Results: No significant difference between groups was seen for systemic leukocyte counts, global function, or water content. Endothelial function was significantly protected as assessed by response to both calcium ionophore (endothelial-dependent, receptor-independent relaxation: leukocyte-depleted, 72% +/- 19% of endothelin-induced constriction versus control, 46% +/- 14%; p < 0.05) and acetylcholine (endothelial-dependent, receptor-dependent relaxation: leukocyte-depleted, 83% +/- 11% versus control, 44% +/- 15%; p < 0.05).
Conclusions: Leukocyte-mediated endothelial reperfusion injury can be attenuated by leukocyte depletion during reperfusion.