To study the protective effect of sodium butyrate on glycocalyx layer of pulmonary vascular endothelium in severely scalded rats and its possible mechanism.

One hundred and fourty four adult male SD rats were randomly divided into sham injury + saline group (n=24), sham injury + sodium butyrate group (n=24), scald + saline group (n=48), scald + sodium butyrate group (n=48) according to the random number table method. The full thickness degree scald models with 50% total body surface area: Rats in the scald + saline group and scald + sodium butyrate group were anesthetized and prepared in a water bath at 80 ℃ (back 15 s, abdomen 8 s, lower limbs 15 s). The rats in the sham injury + saline group and the sham injury + sodium butyrate group were immersed in water at 37 ℃ for the same time. The sham injury + sodium butyrate group and the scald + sodium butyrate group were injected subcutaneously with sodium butyrate (300 mg/kg); the sham injury + saline group and the scald + saline group were immediately injected subcutaneously with 0.5 mL of 0.9% sodium chloride solution. Rats were sacrificed at 3 and 6 h after scald, and samples were collected. The broncho-alveolar lavage fluid (BALF) concentration, lung wet-dry weight ratio were measured; lung polyligand proteoglycan-1(SDC-1), matrix metalloproteinase 9 (MMP-9) and vascular endothelial growth factor (VEGF) were measured using Western blotting and enzyme-linked immunosorbent assay. Data were compared by One-way analysis of variance and Newman-Kueuls method.

(1) At 3 and 6 h after scald, the BALF protein concentration in the scald+ saline group was (0.657 5±0.045 5) and (0.684 1±0.076 0) mg/mL, which were higher than those in the sham injury + saline group (0.476 6±0.065 8) mg/mL, the differences were statistically significant (q= 7.188, 8.243; with P values below 0.05); the lung wet-dry weight ratio of the scald+ saline group were 4.545 1±0.444 4, 4.795 1±0.606 6, which were higher than that of the sham injury + saline group (2.636 0±0.157 5), the differences were statistically significant (q=10.950, 12.380; with P values below 0.05). At 3 and 6 h after scald, the BALF protein concentration in the scald + sodium butyrate group was (0.541 5±0.071 4) and (0.538 1±0.063 6) mg/mL, which were lower than those in the scald + saline group [(0.657 5±0.045 5) and (0.684 1±0.076 0)]. the differences were statistically significant (q=4.610, 5.799; with P values below 0.05); and at 3 and 6 h after scald, the lung wet-dry weight ratio of the scald + sodium butyrate group were 3.626 6±0.446 1, 3.4779±0.510 7, which were lower than those in the scald + saline group, and the differences were statistically significant (q=5.269, 7.555; with P values below 0.05). (2)The results of Western blotting analysis showed that at 3 and 6 h after scald, the expression levels of SDC-1 in the lung tissue of the scald + saline group was 0.376 1±0.075 7 and 0.329 8±0.074 9, respectively, and that of the sham injury+ saline group were all 1.000 0±0, and the differences were statistically significant (q=13.280, 14.260; with P values below 0.05). At 3 and 6 h after scald, the expression level of SDC-1 in the lung tissues of the scald+ sodium butyrate group were 0.760 5±0.207 1 and 0.678 3±0.117 9, respectively. The scald+ sodium butyrate group was significantly higher than those of the scald+ saline group, the differences were statistically significant (q=8.180, 7.417; with P values below 0.05). At 3 and 6 h after scald, the expression levels of MMP-9 and VEGF in the lung tissues of the scald + saline group were (MMP-9: 2.683 4 ± 0.318 8, 2.655 6 ± 0.448 9; VEGF: 3.806 3 ± 0.703 8, 2.850 0 ± 0.396 3). The expression levels of MMP-9 and VEGF in the sham injury+ saline group were both 1.000 0± 0, and the scald + saline group was lower than those in the sham injury + saline group, and the differences were statistically significant [(MMP-9: q=9.356, 9.202) (VEGF: q=12.7, 8.375); with P values below 0.05]. At 3 and 6 h after scald, the expression levels of MMP-9 and VEGF in the lung tissue of the scald + sodium butyrate group were (MMP-9: 0.995 2 ± 0.378 5, 1.527 1 ± 0.342 8; VEGF: 1.574 6 ± 0.216 0, 1.721 5 ± 0.341 8), which were lower than the scald+ saline group, and the differences were statistically significant [(MMP-9: q=9.383, 10.1), (VEGF: q= 6.272, 5.108); with P values below 0.05]. (3)The results of enzyme-linked immunosorbent assay showed that at 3 and 6 h after scald, the levels of MMP-9 and VEGF protein in lung tissue in the scald + saline group were higher than those in the sham injury + saline group, the differences were statistically significant [(MMP-9: q= 8.850, 8.436); (VEGF: q= 9.090, 9.186); with P values below 0.05]; the content of SDC-1 protein was significantly reduced, and the differences were statistically significant (q= 8.296, 8.331; with P values below 0.05). The contents of MMP-9 and VEGF in the lung tissues of the scald + sodium butyrate group were statistically significantly lower than those of the scald + saline group at 3 and 6 hours after the scald, the differences were statistically significant [(MMP-9: q= 6.579, 6.939), (VEGF: q= 7.853, 7.768); with P values below 0.05], SDC-1 protein content was significantly higher than those in the scald + saline group, the differences were statistically significant (q=6.265, 4.456; with P values below 0.05).

Sodium butyrate can restore the damage of pulmonary vascular glycocalyx layer in scald rats, the mechanism may be related to MMP-9 and VEGF pathways.

Burns; Endothelium, vascular; Matrix metalloproteinase 9; Syndecan