Distinct temporal regulation of neutrophil recruitment increases tissue I/R injury in males. Male and female rats were subjected to 30-min mesenteric ischemia followed by up to 2-h reperfusion. (A) Representative images of portions of male and female small intestine at the end of reperfusion, demonstrating redness and edema in males following I/R but no observable change in females. (B-C) Leukocyte/vessel wall interactions throughout reperfusion in mesenteric venules, measured by intravital microscopy: (B) Leukocyte adhesion and (C) number of tissue leukocytes at different distances away from venule (sham, n = 5 rats/group; I/R, n = 8 rats/group). (D) Circulating CD68+ monocytes in males and females during ischemia and reperfusion. Data are presented as mean ± sem. §P 0.05 by one-way ANOVA. (PDF 811 kb)