OBJECTIVETo investigate the protective effect of insulin on vascular endothelial cells of rats at early post-burn stage,and its mechanism.

METHODSAdult male Sprague-Dawley rats were randomly divided into 3 groups: i. e, sham scald group (n = 7), scald group (n = 7) and treatment group (n = 7). The rats in the latter 2 groups were subjected to 30% TBSA full-thickness burns with 94 degrees C water, and the sham scald rats were treated with 37 degrees C water. Intra-peritoneal injection of 40 ml/kg isotonic saline solution and subcutaneous injection of 3 units/kg insulin were given to the rats in treatment group after being subjected to 30% TBSA full-thickness burns. Subcutaneous injection of equal amount of isotonic saline was given to the sham and burn groups. The changes in vascular endothelial cell structure were observed with electron microscopy at 24 post-scald hours(PSH). Meanwhile, the blood glucose contents, the serum levels of nitric oxide (NO) and nitric oxide synthetase (NOS) were determined with oxidase method and colorimetric method, respectively.

RESULTSThe injury of arterial endothelial cells in the treatment group was obviously alleviated compared with that in burn group. The blood glucose content in the treatment group (7.1 +/- 0.7 mmol/L) was significantly lower than that in scald group (8.2 +/- 1.0 mmol/L, P < 0.05), though it was much higher in both groups than that in sham scald group (4.9 +/- 0.8 mmol/L, P < 0.01) at 24 PBH. The serum content of NO, total NOS and cNOS in treatment group were obviously higher than those in scald group (P < 0.01), but there was no obvious difference in iNOS content between the two groups(P > 0.05).

CONCLUSIONInsulin exhibits protective effect on vascular endothelial cells in severely scalded rats at the early post-burn stage, and it is attributed to its promotion of cNOS level leading to NO production.