Experimental Study On The Effects Of Nitric Oxide On PAAF Induced Acute Lung Injury In Rats.

Objective 1. To investigate the effects of nitric oxide on the pancreatitis associated ascites fluid (PAAF) induced acute lung injury (ALI). 2. Establish a rat model of perforative peritonitis (PP) following upper gastric perforation, to induce acute lung injury by introperitoneally injection of perforative peritonitis associated fluid (PPAF) and to investigate the non-specificity of PAAF induced acute lung injury.Methods 160 SD rats. Pancreatitic associated ascites fluids (PAAF) were collected within 7h after acute necrotizing pancreatitis induced in 40 rats by by intraductal injection of 5％sodium taurocholate with a dose of 1ml/Kg. Perforative peritonitis (PP) model in 40 rats following upper gastric freforation were induced by cutting off 1/2 of the duodenal ampulla and sinus ventriculi suspension were added. Perforative peritonitis associated fluids (PPAF) were collected within 7h. Ascites were centrifugated. 8 rats were randomly selcted as ANP group and PP group respectively. 80 rats were randomly divided into four guoups, 0.9％NS control group (n=16): 0.9％NS were peritoneally injected with a dose of 20ml/Kg. PAAF group (n=16): PAAF were peritoneally injected with a dose of 20ml/Kg. PPAF group (n=16): PPAF were peritonealy injected with a dose of 20ml/Kg. PAAF+L-Arg group (n=16): L-Arg was injected by peripheral vein with a dose of 100mg/Kg 10min before PAAF were peritoneally injected. PPAF+L-Arg group (n=16): L-Arg was injected by peripheral vein with a dose of 100mg/Kg 10min before PPAF were peritoneally injected. Each group was randomly subdivided into 7h and 12h group. Blood WBC were counted, serum NO level and MDA level were tested, MPO in lung tissue and protein in bronchoalveolar lavage fluid (BALF) were analyzed. Lung injury and wet/dry ration were evaluated, apoptosis of lung cell were analysed by flow cytometry.Results Serum NO and MDA, protein in BALF, cell apoptosis rate were higher in 12h subgroup of PAAF group and PPAF group than their corresponding 7h subgroups (P＜0.05 or P＜0.01 or P=0.000), which reached to ANP and PP model group level in 7h (P＞0.05). In PAAF+L-Arg group and PPAF+L-Arg group, higher serum NO level in 7h and 12h subgroup were observed than their corresponding subgroup in PAAF group and PPAF group, but lower serum MDA, lower MPO in lung tissue, lower lung wet/dry tatio, attenuated lung injury evaluation, lower protein level in BALF and lower cell apoptosis rate (P＜0.05 or P＜0.01 or P=0.000). No statistic difference was observed between 7h and 12h subgroup in PAAF+L-Arg group and PPAF+L-Arg group in each item. In ANP group and PP model group, serum NO was in positive correlation with serum MDA, MPO in lung tissue, protein in BALF and cell apoptosis rate. But observed negative correlation in PAAF group, PPAF group, PAAF+L-Arg group and PPAF+L-Arg group. Serum MDA was in positive correlation with cell apoptosis in each group.Conclusions Acute lung injury in healthy rats can be induced by introperitoneally injection of PAAF and PPFA. Imbalance of oxidation and anti-oxidation system is the pathophysiological base of acute lung injury induced by PAAF. Cell apoptosis occured in ALI. Nitric oxide acts as a protective factor in ALI by preventing neutrophil infiltration and MPO release, and attenuating the permeability of alveolus capillary.