OBJECTIVE: To elucidate the pathogenic role of leukotriene B4 (LTB4) in pulmonary hyper-permeability and inflammation induced by lung-protective mechanical ventilation (LPMV) in rabbits. METHODS: Thirty-two healthy Japanese white rabbits were randomized into 4 groups for treatment with vehicle or bestatin (a leukotriene A4 hydrolase inhibitor that inhibits LTB4 production) administered intragastrically at the daily dose of 8 mg/kg for 5 days, followed by sham operation (group S and group BS, respectively, in which the rabbits were anesthetized only) or LPMV (group PM and group BPM, respectively, in which the rabbits received ventilation with 50% oxygen at a tidal volume of 8 mL/kg for 5 h). The concentrations of LTB4 and cyclic adenosine monophosphate (cAMP) in the lung tissues were analyzed by ELISA. cAMP content, protein kinase A (PKA) protein expression and the Rap1-GTP protein to total Rap1 protein ratio were determined to assess the activities of cAMP/PKA and Rap1 signaling pathways. The lung injury was evaluated by assessing lung permeability index, lung wet/dry weight ratio, polymorphonuclear leukocyte (PMN) count in bronchoalveolar lavage fluid (BALF), pulmonary myeloperoxidase (MPO) activity and lung histological scores. RESULTS: None of the examined parameters differed significantly between group S and group BS. All the parameters with the exception of lung histological score increased significantly in group PM and group BPM as compared to those in group S ( CONCLUSIONS LPMV can induce LTB4 overproduction to down-regulate cAMP/PKA and Rap1 signaling pathways in the lungs of rabbits, which results in lung hyper-permeability and inflammation. Bestatin can inhibit LTB4 production in the lungs to protect against LPMV-induced lung hyper-permeability and inflammation.
Animals ; Bronchoalveolar Lavage Fluid ; Leukotriene B4 ; Lung ; Lung Injury/prevention & control* ; Neutrophils ; Rabbits ; Respiration, Artificial/adverse effects*

Rapidly and accurately quantitative analysis of whole-cell sugars in some strains of actinomycetes by GC-MS was performed in this paper. After the polysaccharides were hydrolyzed, deoxidized and esterified , the alditol acetate derivates was analyzed by GC-MS. The derivates of rhamnose, ribose, arabinose , xylose, madurose, mannose, glucose, galactose were separated commendably under this condition. The ratio of the peak area was calculated to get the relative percentage of the various sugars.