Effects of exendin-4 on rat cardiomyocyte apoptosis early after severe scald injury / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of exendin-4 on cardiomyocyte apoptosis in the early stage after scald injury in rats and explore the mechanisms.</p><p><b>METHODS</b>Fifty-four healthy adult SD rats were randomly divided into normal control group (n=6), scald group (n=24) and scald with exendin-4 treatment group (n=24). In the latter two groups, the rats were subjected to 30% TBSA full-thickness scald burns on the back, and Parkland formula was used for determining the resuscitation fluid volume. In exendin-4 treatment group, the rats received intraperitoneal injection of 5 µg/kg exendin-4 after the scald. Apoptosis of the cardiomyocytes from the left ventricle was determined by TUNEL assay and the activity of caspase-3 in the myocardium was assessed.</p><p><b>RESULTS</b>In the scald group, the apoptotic index of the cardiomyocytes was increased at 6 h post-burn, reaching the peak level at 12 h, and maintained a significantly higher level than that in the normal control at 48 h (P<0.05). Myocardial caspase-3 activity in the scald group was increased at 6 h post-burn and reached the peak at 12 h, still maintaining a high levels at 24 h (P<0.05). In exendin-4 treatment group, the apoptotic index of the cardiomyocytes was significantly lower than that in the scald group at 6, 12, 24 and 48 h post-burn (P<0.05), and so was the caspase-3 activity at 6, 12 and 48 h (P<0.05). A significant positive correlation was found between the apoptotic index of the cardiomyocytes and myocardial caspase-3 activity in the rats (P<0.05).</p><p><b>CONCLUSION</b>Exdendin-4 can inhibit rat cardiomyocyte apoptosis early after scald injury possibly by suppressing caspase-3 activity in the myocardium.</p>

Changes of aquaporin-1 expression in rat myocardium after severe burn / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in the myocardial expression of aquaporin-1 (AQP1) protein and its association with myocardial edema in rats with severe burns.</p><p><b>METHODS</b>Forty-eight healthy adult Wistar rats were randomly divided into normal control group (n=6) and burn injury group with third degree burn of 30% total body surface area, and the latter group was further divided into 2, 4, 8, 12, 24, 48 and 72 h groups. The changes of myocardial water content were investigated by dry-wet weight methods. Enzyme-linked immunosorbent assay was used to detect the changes in AQP1 expression at different time points after sever burns.</p><p><b>RESULTS</b>The myocardial water content and AQP1 expression increased significantly 2 h after the burn injury, reaching the peak levels at 12 h and remaining higher than the normal level at 48 h. A significant positive correlation was found between myocardial water content and AQP1 expression in the rats (r=0.868, P<0.01).</p><p><b>CONCLUSION</b>The severity of myocardial edema after severe burn is correlated to the expression level of AQPl protein, suggesting the important role of AQPl protein in pathological progression of myocardial edema.</p>

Effect of local treatment with cooling and spray film on early edema of superficial II degree scald burns in rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the anti-inflammatory effect of early local treatment with cooling and spray film on scald burn injury in rats.</p><p><b>METHOD</b>Seventy-five Wistar rats were randomly divided into 5 groups including the sham-scalded group, untreated scald group, cooling group, spray film group, and cooling plus spray film group with corresponding treatments. After gross observation of the wounds, the tissues at the wounds were sampled at different time points after the injury to determine the total water content (wet: dry weight ratio) and prostaglandin E(2) (PGE(2)) levels using radioimmunoassay (RIA).</p><p><b>RESULTS</b>Treatment with cooling and spray film significantly alleviated the swelling and effusion of the scald burns. At each of the time points, the water content and PGE(2) levels in the cooling group, spray film group and cooling plus spray film group were all lower than those in untreated scald group (P<0.01), but all higher than those in the sham-scalded group (P<0.01). The water content and PGE(2) levels were the lowest in cooling plus spray film group, and a significant correlation was noted between the water content and PGE(2) levels in the untreated scald group, cooling group, spray film group and cooling plus spray film group (P<0.01).</p><p><b>CONCLUSIONS</b>Local treatment with cooling and spray film can alleviate the edema of superficial II degree scald burns in rats probably by reducing the levels of the inflammatory cytokines in the local tissues.</p>