Objective：To investigate the protective efficiency of low molecular weight heparin (LMWH) on lung injury in severe acute pancreatitis (SAP).
Methods：SD rats were randomly divided into 3 groups: (1) Sham operation (S) group，(2) SAP group，(3) LMWH treatment (LT) group：LMWH was administrated 4 hours after SAP model was constructed. The levels of serum amylase, endothelin1(ET-1), tumor necrosis factor α (TNF-α), lung wet/dry weight ratios, pulmonary morphology, the expressions of P65 mRNA and P65 protein in pulmonary specimens were detected at 1d after the models were set up, and the 3 days survival rate in each group was also observed.
Results：(1) The levels of serum amylase, TNF-α,  ET-1 in SAP group were significantly increased than those in S group and LT group (all P<0.001), and the level of serum amylase in LT group was significantly increased than that in S group (P<0.05). (2) The expression of P65 protein and P65 mRNA in pulmonary specimens of SAP group was significantly lower than that in S group and in LT group (all P<0.05). (3)The lung wet/dry weight ratio in SAP group was significantly increased than that in S group and LT group (all P<0.001). (4)The inflammatory cells infiltration, hyaline membrane and increase of pulmonary microvascular permeability in alveoll in SAP group were significantly serere than those in LT group. (5) The 3 days survival rate in SAP group (25.0%) was significantly lower than that in S group (100.0%) and LT group (87.5%) (all P<0.05).
Conclusions：LMWH therapy can improve the survival rate of SAP, and might be related to the amelioration of the lung injury by down-regulating the levels of cytokines release through suppressing the activity of nuclear factor kappa B and improving the pulmonary microcirculatory by down-regulating the level of serum ET-1.