Fig. 1

Distinct temporal regulation of neutrophil recruitment protects against I/R injury in females. Male and female rats were subjected to 30-min mesenteric ischemia followed by up to 2-h reperfusion. a Representative images of segments of male and female mesentery at 2 h of reperfusion, stained with hematoxylin and eosin, demonstrating fewer nucleated cells within and around female venules. Dashed lines approximately demarcate venule lumen. b Accumulation of peritoneal RP1+ neutrophils, measured by cytometry. c Proportion of intestinal necrosis, measured by nitroblue tetrazolium. Sham n = 5 rats/group, I/R n = 8 rats/group. d, e Leukocyte/vessel wall interactions throughout reperfusion in mesenteric venules, measured by intravital microscopy: d leukocyte flux and e leukocyte rolling velocity (sham n = 11 rats/group, I/R n = 18 rats/group). f Circulating RP1+ neutrophils, measured by flow cytometry. g Direct correlation between number of circulating neutrophils and extent of intestinal necrosis in both males and females, measured at 30-min and 2-h reperfusion. Sham n = 5 rats/group, I/R n = 8 rats/group. Data are presented as mean ± sem. ***P < 0.001 by one-way ANOVA. §P < 0.001 by two-way ANOVA, and ‡P < 0.05 or #P < 0.001 by Bonferroni’s post-test compared to male I/R. ns denotes P > 0.05