Lack of reperfusion-induced venular leukocyte adherence following local arteriolar ischemia

Leukocyte adhesion in postcapillary venules has been implicated as a primary determinant of microvascular dysfunction that occurs following ischemia-reperfusion (I/R). The mechanisms of leukocyte recruitment have not been fully established. The present study concerns evidence in the literature that I/R in one organ may initiate a systemic effect that results in inflammatory consequences in another. In this investigation, we used a model of mesenteric I/R in the rat. In one group (N = 13), I/R has induced by temporarily occluding the superior mesenteric artery (SMA) for 30 minutes. In the another group (N = 9), localized I/R was induced by micropipette occlusion of a mesenteric arteriole (for 30 minutes) that perfused the monitored venule(s). The responses of the two groups were different. No increase in venular leukocyte adherence was observed with local I/R; instead, there was a trend for a small decrease. In contrast, a significant increase in adherence (p<0.001) was observed with SMA I/R. Also of interest, both local and SMA I/R similarly prevented the decrease in leukocyte rolling that occurs in time control experiments following mesenteric exteriorization (N = 8). These results suggest that mesenteric I/R-induced leukocyte adherence (but not rolling) may be dependent on a mediator released into the systemic circulation.