Objective       To determine the role of mitsugumin 53 (MG53) in the protective effect of remote ischemic preconditioning (RIP) for lung ischemia/reperfusion (I/R) injury.      Methods      Lung ischemic/reperfusion injury model was established in SD rats by l

eft thoracotomy

clamped left hilum for 1 h

and then released for reperfusion for 1 h. For RIP

the left femoral artery was clamped for 5 min followed by being released for 5 min (this cycle was repeated for 3 times). This RIP procedure was done in 30 min before lung ischemic/reperfusion injury. SD rats (n=60) in both sexes (10 to 12 weeks old

weighting 235±15 g) were randomly divided into 3 groups

that is

sham group

IR group

and lung IR pretreated with RIP group. Male and female MG53 knockout mice (n=24) (8 to 12 weeks old

weighting 27.5±2.5 g) were divided into 2 groups

IR and RIP groups. After I/R period

the arterial blood samples were collected for arterial blood gas analysis

the lung tissues were obtained for measurement of wet/dry (W/D) ratio

and Western blot analysis was used for the protein expression of MG53. The survival rate were recorded and compared among the groups.      Results      In SD rats

lung I/R injury lowered PaO

2

to 46.60±5.94 mmHg

which was improved by pretreated with RIP

by increasing the value to 73.40±5.94 mmHg (P＜0.05). At the same time

the W/D ratio and survival condition were also improved in RIP group than IR group. The expression of MG53 in the lung tissue was markedly increased in the former than the latter group (2.03±0.53 vs 0.79±0.17

P＜0.05). However

all the protective effects

including the effect on PaO

2

were lost in the MG53 knockout mice.      Conclusion      MG53 participates in the protective effect of RIP against the lung ischemic/reperfusion injury.