Effects Of Hypertonic-hyperoncotic Solution On Endotoxin-induced Acute Lung Injury In Rats

Objective To investigate the protective effects of hypertonic-hyperoncotic solution (HHS) on the acute lung injury induced by lipopolysacchharide in rats.Methods Models of acute lung injury (ALI) in rats were induced by lipopolysacchharide (LPS, 5 mg/kg, iv). Forty-eight Sprague Dawley rats weighing 180 g - 220 g were randomly divided into 3 groups with sixteen animals each: (1) control group received only normal saline; (2) LPS group received normal saline 4 ml/kg infusion 2 min after intravenous LPS 5 mg/kg; (3) HHS group received HHS 4 ml/kg infusion 2 min after intravenous LPS 5 mg/kg. The rats were anesthetized with urethane. We infused normal saline, LPS or HHS via the femoral vein catheter. They were killed by exsanguinations at 1h or 4 h after intravenous LPS or normal saline administration. Then the lungs were removed, left lung was lavaged and the bronchoalveolar lavage fluid (BALF) was collected for determination of albumin concentration. Right lung was used for measurement of wet/dry lung weight ratio and myeloperoxiase (MPO) activity. Pathologic changes of lung tissue were observed microscopically. We also detected the expression of ICAM-1 in lung vascular endothelium by immunohistochemical.Results At 1h, as compared with NS group, wet/dry lung weight ratio and MPO activity in lungs increased significantly in LPS group and HHS group(P<0.05). At 4h, obvious ALI pathological manifestation in the lungs of LPS and HHS group rats was observed compared with NS group, and wet/dry lung weight ratio and MPO activity in lungs increased significantly in LPS group(P<0.01) as well as the albumin concentration in BALF(P<0.01),and the expression of ICAM-1 was increased at 4h (P<0.01); Compared with LPS group, the pathological manifestation in the lungs was ameliorated and wet/dry lung weight ratio, MPO activity in lungs and the albumin concentration in BALF decreased significantly in HHS group (P<0.01). As compared with LPS group , HHS can obviously decrease expression of ICAM-1 in lung vascular endothelium(P<0.01).Conclusion LPS injection resulted in marked lung damage and elevated levels of W/D ratio and MPO activity in the lung as well as the albumin concentration in BALF. Furthermore, these changes are associated with increased expression of ICAM-1 in the lung vascular endothelium. HHS could reduce pulmonary inflammation caused by lipopolysacchharide in rats.The anti-inflammatory effect of HHS may be connected with the inhibition of expression of ICAM-1 in the lung vascular endothelium and inhibition of the infiltration and activation of neutrophil.