[Expression of aquaporin-1 in myocardium of rats in the early stage after scald and its relationship with myocardial edema].

OBJECTIVE: To investigate the changes in aquaporin-1 (AQP-1) expression in myocardium of scalded rats in early stage of a burn injury, and to analyze its relationship with myocardial edema. METHODS: Thirty-six healthy Wistar rats were divided into normal control (n = 6, without scald) and scald (n = 30) groups according to the random number table. Rats in scald group were inflicted with 30%TBSA full-thickness scald on the back, and intraperitoneally injected with Ringer's solution for antishock treatment. Myocardium tissue from left ventricle and serum specimen in rats of scald group were collected at post scald hours (PSH) 2, 8, 12, 24, and 48 (with 6 rats at each time point). Myocardial water ratio was determined by dry-wet weight method. The distribution of AQP-1 protein in myocardium was observed with immunohistochemical staining. The expression of myocardial AQP-1 mRNA was assessed with quantitative real-time PCR. The serum content of cardiac troponin-I (cTnI) was determined with ELISA. The rats in normal control group were detected with above-mentioned method. Data were processed with one way analysis of variance and LSD test. Correlation analysis was performed between AQP-1 mRNA and myocardial water ratio, AQP-1 mRNA and the serum content of cTnI in scald group at each time point. RESULTS: Compared with that in normal control group, the myocardial water ratio in scald group was markedly increased during PSH 8-48 (P values all below 0.01), and it peaked at PSH 12 [(80.79 ± 0.12)%]. In both groups, AQP-1 was mainly expressed in endothelial cells of capillaries and pericellular membrane of myocardial cells. The expression of AQP-1 in scald group was markedly increased from PSH 2 to PSH 48. The expression of myocardial AQP-1 mRNA in scald group was markedly higher from PSH 2 to PSH 48 than that in normal control group (P values all below 0.01), and it peaked at PSH 12 [(6.2 ± 0.7)%]. The serum content of cTnI in scald group was obviously higher from PSH 2 to PSH 48 than that in normal control group (P values all below 0.01), and it peaked at PSH 12 [(5.83 ± 0.51) µg/L]. There were statistically positive correlations between AQP-1 mRNA expression and myocardial water ratio (r = 0.849, P < 0.01), AQP-1 mRNA expression and the serum content of cTnI (r = 0.973, P < 0.01) in scald group. CONCLUSIONS: AQP-1 may play a key role in the development of myocardial edema in rats with scald.

[Changes of aquaporin-1 expression in rat myocardium after severe burn].

OBJECTIVE: To investigate the changes in the myocardial expression of aquaporin-1 (AQP1) protein and its association with myocardial edema in rats with severe burns. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

[Effect of early enteral feeding on the expression of aquaporin 1 in edematous small intestinal tissues of rats after severe burn].

OBJECTIVE: To investigate the changes in the expression of aquaporin 1 (AQP-1) in edematous small intestinal tissues of rats after severe burn and the effect of early enteral feeding on its expression. METHODS: Ninety normal adult Wistar rats were randomly divided into normal control group (n=6), burn model group (n=42, with 30% TBSA III degrees) and early feeding group (n=42). Dry weight method, ELSIA and immunohistochemistry were used to observe and detect the water content and expression of AQP-1 in the intestinal tissue at 1, 4, 8, 12, 24, 48, and 72 h after the burns. RESULTS: In the burn model group, the water content in the intestinal tissue increased at 4 h after the injury, reaching the peak level at 48 h; AQP-1 expression decreased at 8 h after severe burn and reached the lowest level at 48 h. AQP-1 expression level showed a significant inverse correlation to the water content (P<0.01). Compared with the burn model group, the rats in the early feeding group showed increased AQP-l expression and lessened edema in the small intestines, also demonstrating an inverse correlation between water content and AQP-l expression (P<0.01). CONCLUSION: Intestinal AQP-1 expression gradually decreased and edema worsened in rats early after severe burn, reaching the lowest or the peak levels 48 h after the injury with an inverse correlation between them. Early enteral feeding can increase the expression of AQP-l in the small intestine to ameliorate the intestinal edema in rats with severe burn injury.