The results indicated that the degree of intestinal mucosal injury in the ischemia–reperfusion group was significantly correlated with the concentrations of serum zonulin and claudin-3, which increased significantly with prolonged ischemia–reperfusion time, peaking at 24 h post-reperfusion and then gradually decreasing, yet remaining higher than that of the sham-operated group. The gene discussed is CLDN3; the disease is ischemia.