The animal study was under the approval of the Ethics Committee of Ningbo No.2 Hospital. Adult male Sprague-Dawley rats (Sprague-Dawley) were provided by the Vital River (Beijing, China). The animals were fed with standard food and water at a 12-h light/dark cycle at 23 ± 2°C. For the establishment of burn models, rats were randomized into the control (n=10), gasoline burn (n=30) and chromic acid burn (n=30) groups, and the two burn groups were further divided into the 5%, 10% and 20% burn subgroups with ten rats in each group. After anesthesia with pentobarbital sodium (40 mg/kg), rat dorsum was shaved and removed with sodium sulfide to expose 5%, 10% or 30% of the body surface area. before the experiment. Animals in the gasoline burn group were anaesthetized and then the 3% solidified gasoline (1 mL/20 cm 2 ) was smeared in the exposed area and ignited to burn for 30 seconds with the other area covered using a damp cloth. For rats in the chromic acid burn group, the exposed dorsum was immersed in chromic acid at 90°C for 15 seconds. For rats in the control group, the dorsum was immersed in water at 37°C for 15 seconds. The injured tissue and blood samples were collected from rats in each group. Blood samples were centrifuged at 1000 × g for 10 min. All animals were sacrificed at 48 hours following burn injury. The intestine, heart, liver, lung and kidneys were obtained and subject to histological analysis.