Effect Of Ketamine On The Expression Of HSP70 In Myocardium And Brain In Severely Burned Rats

Objective To investigate the effect of ketamine on the expression of HSP70 in myocardium and brain in severely burned rats for its possible mechanism of myocardial and neural protection after severe burns.Methods One hundred and twenty-four male Wistar rats were randomly divided into 3 groups:control group(group C)(n=20),burn group(group B)(n=52) and ketamine group(group K)((n=52).The dorsum of the animal was shaved and immersed in water at 92℃for 18 seconds in groups B and K,which resulted in a full-thickness burn involving 30%total body surface area.They were immediately resuscitated with 40 ml/kg lactated Ringer intraperitoneally.The group K was injected with katemine(40 mg/kg im) immediately 15 minutes after the burn injury.The group B was injected with saline(the same volume of the katemine).Rats in groups B and K were respectively sacrificed at 3,6,12 and 24h after administration.There were 8 rats at each time point of the two groups.Myocardium and brain samples were collected for HSP70 detection by Western blot analysis.Survival rates of the other rats of each group were measured at 3h,6h,12h,24h,2d,4d,8d,10d.There was no management in group C,and the rats were measured as support controls after the end of experiment.Results1.The expression of HSP70 in myocardium The expression of HSP70 in myocardium was higher in groups B and K than that in group C at 3,6,12 and 24h (P＜0.05).It reached the peak at 24h in myocardium after administration.The expression of HSP70 was higher in group K than that in group B at 3,6h(P＜0.05).2.The expression of HSP70 in brain The expression of HSP70 in brain was higher in groups B and K than that in group C at 3,6,12 and 24h(P＜0.05).It reached the peak at 12h in brain after administration.The expression of HSP70 was higher in group K than that in group B at 3,6h(P＜0.05).3.Groups of animals observed for survival No animals died until 10 days in group C.Survival in group B was 95%(19 from 20 animals) at 3 hours,90%(18/20) at 6 hours,80%(16/20) at 12 hours,75%(15/20) at 24 hours,70%(14/20) at 2 days,55 %(11/20) at 4 days,40%(8/20) at 8 days and 30%(6/20) at 10 days.Survival in group K was 100%(20/20) at 3 hours,100%(20/20 animals) at 6 hours,95%(19/20) at 12 hours,85%(17/20) at 24 hours,80%(16/20) at 2 days,80%(16/20) at 4 days, 75%(15/20) at 8 days and 70%(14/20) at 10 days.There is no statistically significant difference in the survival rates between group K and group B at 3h,6h,12h,24h,2d, 4d,8d(P＞0.05).Comparison of survival rates between group K and group B showed statistically significant at 10 days(P＜0.05).Conclusions1.Ketamine can protect myocardium in severely burned rats through up-regulating the expression of HSP70 in myocardium.2.Ketamine can protect brain in severely burned rats through up-regulating the expression of HSP70 in brain..