Fucoidin reduces coronary microvascular leukocyte accumulation early in reperfusion.

BACKGROUND Leukocytes rapidly accumulate in the heart early in reperfusion after ischemia, contributing to reperfusion injury. The purpose of this study was to determine whether treatment with the selectin blocker fucoidin (FCN) would attenuate early leukocyte retention in coronary venules and capillaries during low flow reperfusion. METHODS Isolated rat hearts subjected to 30 minutes of 37 degrees C, no-flow ischemia were initially reperfused with blood containing labeled leukocytes, followed by reperfusion with a Krebs red cell solution. The deposition of leukocytes in coronary capillaries and venules was observed using intravital microscopy. Three groups were studied: nonischemic control hearts, untreated postischemic hearts reperfused at low flow, and postischemic hearts reperfused at low flow, where both the hearts and the blood reperfusate were pretreated with FCN (0.36 mg/mL blood). RESULTS In the ischemia-reperfusion group, we observed a rapid and significant increase in leukocyte accumulation in both capillaries and venules. Treatment with FCN significantly reduced the leukocyte accumulation in both capillaries and venules (p<0.05). In addition, FCN significantly reduced the persistence of leukostasis in both capillaries and venules, indicating that FCN affected a transient adhesion process. CONCLUSIONS These results suggest that the selectin family of leukocyte-endothelial cell adhesion proteins mediates the initial retention of leukocytes in both coronary capillaries and venules during reperfusion. Selectin blockade may be effective in reducing the contribution of leukocytes to early reperfusion injury.