| Objective: to investigate the effects of delayed resuscitation on severe burned rats’ hearts after preconditioning and postconditioning.Method: SD rats of both genders,weighing 250g-300 g,were randomly devided into four groups: delayed resuscitation group;delayed resuscitation & limb-ischemia perconditioning group; delayed resuscitation & limb-ischemia postconditioning group;delayed resuscitation & limb-ischemia perconditioning with postconditioning group. The numbers of samples in the first two groups were both 15, and the last two groups were both 10. under brief ether anesthesia,dorsum of the rats were shaved,exposed to 94℃ water bath for 12 seconds,which resulted in partial thickness third-degree skin burn involving 30% of the total body surface area, Each group was treated with fluid resuscitation after 6 hours of burn, 1/3 of fluid infusion were provided in 6 hours after burn and 1/6 fluid infusion were provided in 8 hours. 2 hours after burn, double lower limbs of rats in the second group were ligated with rubber tourniguet for five-minute untill vessel pulsatility could not be detected by Doppler blood stream detector, and then released five-minute. This treatment was repeated 4 times. 5 hours after burn, the third group was treated as same as the second Group, and 2 hours and 5 hours after burn, the fouth group was same treated. The blood and heart specimens of each group were collected at 3 time points in the former two groups after burn, namely 3h, 7h, and 14 h. In the last two groups,the specimens were collected at 7h and 14 h after burn. Five animals from each group were used to collect specimens at each time point. Heart injury was evaluated by levels of serum lactate dehydrogenase(LDH),creatine kinase(CK), creatin kinase-mb isoenzyme(CK-MB) and histopathologic changes in heart injury.Result:1.The serum myocardial enzyme was detected to increase after 3 hours of the burn,and the peak occurred at the 7th hour after the burn, then gradually fell to the lowest point at the 14 th hour.2. In the delayed resuscitation group, the myocardial enzyme values were significantly higher than those in the other three groups, which was the most obvious at the 7th hour(P < 0.05).3.The value of myocardial enzyme in the perconditioning & postconditioning group was significantly lower than that in the perconditioning group and postconditioning group at the 7th and 14 th hour(P < 0.05)and the myocardial enzyme value of perconditioning group was lower than that of postconditioning group at 7th hour(P < 0.05). but the value between perconditioning group and postconditioning group at 14 th hour shows no significant difference(P < 0.05).4. Pathology results showed that the myocardial injury of delayed resuscitation group was more serious than other groups, the injury was most obvious in the 7th hours after burn. In perconditioning & postconditioning group the myocardial injury was observed to be minimal, with perconditioning group is better than the postprocessing group,whereas no significant difference was observed at the 14 th hours.Conclusion:1.Non-invasive limb ischemia preconditioning showed a myocardium-protective effect in rat with delayed resuscitation after sever burn.2. Non-invasive limb ischemic preconditioning treatment was be-tter than the postcontioning treatment.3.Combined application of non-invasive limb ischemic precondi-tioning and postconditioning performed more obvious myocardialprotective effects on the rats with delayed resuscitation after severeburn. |
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