[The timing of infusion of hypertonic saline to exert protective effect on intestinal barrier function in the rabbit with intestinal ischemia/reperfusion injury].

OBJECTIVE: To study the timing of infusion of hypertonic saline solution (HTS) to exert its protective effect on intestinal barrier function in rabbits with intestinal ischemia/reperfusion (I/R) injury.

METHODS: Seventy-two rabbits were randomly divided into four groups (each n=18): sham operation group, I/R group, HTS pretreatment group and HTS delayed treatment group. The intestinal I/R models were produced by blocking the superior mesenteric artery (SMA) for 1 hour followed by release of the SMA. 7.5% HTS (6 ml/kg) was infused in HTS pretreatment group 5 minutes before release of SMA, and HTS was infused in delayed treatment group 2 hours after reperfusion and finished in 5 minutes. Levels of D-lactic acid (D-Lac), lipopolysaccharide (LPS), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) were determined before ischemia and 2, 4, 6 hours after reperfusion. The levels of malonaldehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO) in intestinal tissues of 8 rabbits in each group were measured at 6 hours after reperfusion. Meanwhile the intestinal morphological changes were observed, and the Chin score, which reflected the degree of injury to intestinal mucosa was calculated.

RESULTS: Compared with sham operation group, D-Lac, LPS, TNF-α and IL-10 in I/R group were significantly increased from 2 hours after reperfusion (D-Lac: 18.91 ± 3.46 mg/L vs. 3.92 ± 0.61 mg/L, LPS: 869 ± 85 EU/L vs. 422 ± 27 EU/L, TNF-α: 23.80 ± 4.22 μg/L vs. 3.65 ± 0.51μg/L, IL-10: 8.90 ± 2.75 μg/L vs. 2.53 ± 0.80 μg/L, all P<0.05); MDA, MPO and Chiu score were significantly increased (MDA: 398 ± 28 nmol/mg vs. 173 ± 20 nmol/mg, MPO: 465 ± 52 mU/mg vs. 183 ± 25 mU/mg, Chiu score: 4.36 ± 0.52 vs. 0.38 ± 0.22, all P<0.05), while SOD decreased significantly (35 ± 9 U/mg vs. 52 ± 8 U/mg, P<0.05). Compared with I/R group, the levels of D-Lac, LPS, TNF-α, MDA, MPO and Chiu score in HTS pretreatment group were lower (D-Lac: 11.45 ± 0.92 mg/L vs. 18.91 ± 3.46 mg/L, LPS: 455 ± 114 EU/L vs. 869 ± 85 EU/L, TNF-α: 10.32 ± 2.11 μg/L vs. 23.80 ± 4.22 μg/L, MDA: 221 ± 21 nmol/mg vs. 398 ± 28 nmol/mg, MPO: 271 ± 20 mU/mg vs. 465 ± 52 mU/mg, Chiu score: 1.69 ± 0.24 vs. 4.36 ± 0.52, all P<0.05), while IL-10 and SOD were significantly increased (IL-10: 14.54 ± 2.02 μg/L vs. 8.90 ± 2.75 μg/L, SOD: 90 ± 14 U/mg vs. 35 ± 9 U/mg, both P<0.05). The levels of the above indexes in HTS delayed treatment group were similar to I/R group, and the effect was lower than that in HTS pretreatment group.

CONCLUSIONS: HTS had the protective effect on intestine suffering from I/R injury. But the protective effect was time dependent, and early treatment shows protective effect.