Mild hypothermia protect renal function on ischemia-reperfusion kidney: an experimental study in mice

Objective To investigate the protective effect of mild hypothermia on ischemia-reperfusion kidney and the possible mechanisms. Methods Twenty-four male BALB/c mice were randomly divided into three groups: ischemia-reperfusion group (IR Group), mild hypothermia ischemia-reperfusion group (MH+ IR Group) and normal control group (NC Group), with 8 mice in each group. Another 15 male BALB/c mice were divided into 5 groups, and dealed with mild hypothermia in time gradient (0, 2, 4, 6 and 8 h). The serum creatinine, cold inducible ribonucleic acid-binding protein (CIRP), thioredoxin (Trx), B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein (Bax), superoxide dismutase (SOD) and malondialdehyde (MDA) of kidney tissue of the above three groups were detected 24 h later after ischemia-reperfusion. HE staining was used to detected edema of renal tubular epithelial cell. Terminal dexynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling was used to detected apoptosis of kidney tissue. CIRP expression of 15 male BALB/c mice which just dealed with mild hypothermia was detected. One-way analysis of variance was used to compared serum creatinine, apoptotic cell proportion of kidney tissue, SOD activity and MDA content of the above three groups 24 h later after ischemia-reperfusion. P<0.05 was considered statistically significant. Results The concentration of serum creatinine of IR group and (MH+ IR) group were (153.59±21.29) and (87.44±13.81) mg/dL, which has statistical significance (F=5.41, P<0.05). The edema of renal tubular epithelial cell in IR group was worse than (MH+ IR) group. The apoptotic cell proportion of kidney tissue of IR group and (MH+ IR) group were (37.0±5.7) % and (15.0±2.4) %, which has statistical significance (F=5.41, P<0.05). MH could promote the expression of CIRP and Trx, and increase the ratio of Bcl-2/Bax. The SOD activity of (MH+ IR) group and IR group were (26.9±4.4) and (16.8±2.4) U/mgprot, which has statistical significance (F=3.36, P<0.05). The MDA content of (MH+ IR) group and IR group were (0.76±0.18) and (1.37±0.32) nmol/mgprot, which has statistical significance (F=3.21, P<0.05). Conclusion Mild hypothermia protect mice kidney from ischemia-reperfusion damages, which may by reducing oxidative stress injury. Key words: Kidney transplantation; Mild hypothermia; Ischemia-reperfusion; Mice