OBJECTIVETo 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.

METHODSThirty-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.

RESULTSCompared 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.

CONCLUSIONSAQP-1 may play a key role in the development of myocardial edema in rats with scald.