Intestinal microcirculation and leukocyte behavior in ischemia-reperfusion injury

Polymorphonuclear leukocytes are thought to play a pivotal role in the generation of ischemia-reperfusion-induced mucosal injury; however, their behavior in the intestinal microvasculature following this injury has not been directly examined. In this study intravital microscopy was used to investigate the dynamics of blood flow and leukocyte behavior in the villus, serosal, and mesenteric microcirculation during ischemia-reperfusion in anesthetized hamsters. Thirty minutes of ischemia and 90 min of reperfusion resulted in almost complete microvascular stasis in the villi of control animals, whereas only a few serosal and mesenteric microvessels exhibited stasis. Following reperfusion, there was a significant increase in leukocyte accumulation in all three tissues; however, significantly fewer leukocytes adhered in the villus microvasculature than in the rest of either the mucosa, serosa, or mesentery. Treatment with gamma-hydroxybutyrate (GHB), a compound that we have previously demonstrated to be highly effective in preventing ischemia-reperfusion injury, significantly reduced both the microvascular stasis and leukocyte accumulation in all three vascular beds. This study demonstrates that there are significant differences in the response to ischemia-reperfusion in various intestinal layers and that areas most susceptible to damage are not necessarily those exhibiting the greatest leukocyte accumulation.