Objective:To evaluate the relationship between mitochondrial calcium uniporter protein (MCU)-mediated mitochondrial dynamics and intestinal ischemia-reperfusion (I/R) injury in mice.Methods:Twenty-four wild-type adult male C57BL/6J mice, aged 6-8 weeks, weighing 18-20 g, were divided into 4 groups ( n=6 each) using a random number table method: sham operation group (S group), intestinal I/R group (IIR group), sham operation+ MCU inhibitor Ru360 group (S+ Ru360 group) and intestinal I/R + Ru360 group (IIR+ Ru360 group). The mouse model of intestinal I/R injury was prepared by clamping the root of the superior mesenteric artery for 45 min followed by 2 h of reperfusion in anesthetized animals. Small intestinal tissues were obtained at the end of reperfusion for examination of the intestinal mucosal injury which was scored according to Chiu and for determination of the content of malondialdehyde (MDA) (TBA method), activity of superoxide dismutase (SOD) (WST-8 method), content of lactic dehydrogenase (LDH) (colorimetric method), and expression of MCU, dynamin-related protein 1 (Drp1), recombinant human mitochondrial fission 1 protein (Fis1), mitofusin-1 (Mfn1) and Mfn2 (by Western blot). Results:Compared with S and S+ Ru360 groups, the Chiu′s score and contents of MDA and LDH were significantly increased, the activity of SOD was decreased, the expression of MCU, Drp1 and Fis1 was up-regulated, and the expression of Mfn1 and Mfn2 was down-regulated in IIR and IIR+ Ru360 groups ( P<0.05). Compared with IIR group, the Chiu′s score and contents of MDA and LDH were significantly decreased, the activity of SOD was increased, the expression of MCU, Drp1 and Fis1 was down-regulated, and the expression of Mfn1 and Mfn2 was up-regulated in IIR+ Ru360 group ( P<0.05). Conclusions:The mechanism underlying intestinal I/R injury may be related to MCU-induced promotion of mitochondrial fission, reduction of mitochondrial fusion and mediation of imbalance in mitochondrial dynamics in mice.