In open-chest dogs, 3 hours of myocardial ischemia led to granulocyte accumulation in the ischemic endocardium, which inversely correlated with ischemic blood flow and was enhanced by reperfusion.
Collateral flow is an important mechanism of leukocyte arrival early in ischemic myocardium, and reperfusion further enhances granulocyte accumulation.
Recent evidence indicates that mechanical obstruction of capillaries by leukocytes plays an important role in the "no-reflow" phenomenon in the heart. This entrapment of leukocytes in the microcirculation precedes their recognized role in an inflammatory reaction following ischemia. It is a fundamental rheological mechanism that may be associated with ischemic injury and reflow injury and it has not been elucidated. To explore the accumulation of granulocytes during myocardial ischemia we studied the accumulation of 111Inlabeled autologous granulocytes in acutely ischemic myocardium during 3 h of flow reduction with and without a subsequent period of reflow in open-chest dogs. Granulocytes accumulated in the ischemic endocardium of all animals and, for the majority of dogs, also in the epicardium. Accumulation in the endocardium was enhanced by reperfusion. The entrapped leukocytes may have an influence on the increase in resistance, since regional accumulation of leukocytes in the endocardium inversely correlated with ischemic blood flow during 3 h of ischemia. The tissue water content measured from the wet and dry weights of biopsies showed a significant positive correlation with the number of entrapped granulocytes. These results suggest that collateral flow is an important mechanism of leukocyte arrival early in ischemic myocardium and that reperfusion enhances granulocyte accumulation.
Engler et al. (Tue,) conducted a other in Myocardial ischemia. Experimental myocardial ischemia (flow reduction with or without reflow) was evaluated on Accumulation of 111In-labeled autologous granulocytes in acutely ischemic myocardium. In open-chest dogs, 3 hours of myocardial ischemia led to granulocyte accumulation in the ischemic endocardium, which inversely correlated with ischemic blood flow and was enhanced by reperfusion.