Role of Clara cells in lung ischemia-reperfusion injury in rabbits

Abstract

：Objective To investigatethe role of Clara cells in lung ischemia-reperfusion (I/R) injury in rabbits.MethodsTwenty-four healthy 10-12 month old rabbits of either sex weighing 1.5-2.0 kg wererandomly divided into 3 groups ( n = 8 each) ; group A sham operation (group S) ; group Blung I/R and group C Clara cell elimination+ lung I/R. The animals were anesthetized withiv pentobarbital 30 mg/kg , tracheostomized and mechanically ventilated. In group B and Clung I/R was induced by clamping the left hilum of lung for 60 min followed by 120 minrepeffusion. In group C Clara ceils were eliminated by ventilating the lungs with 89.28mg/m2 naphthalin vapor for 12 h before lung I/R. The animals were killed by iv KCI at theend of 120 min reperfusion after lung isehemia. The left lung was immediately removed formicroscopic examination, determination of W/D lung weight ratio and serum TNF-α level and MDA content. Thepercentage of neutrophi] in bronchoalveolar lavage fluid (BALF) was detected as index oflung injury. The expression of Clara cell secreting protein (CCSP) in the lung wasdetected by immuno-histoebemistry to indicate the number and distribution of Clara cellsin the lung.Results Microscopic examination showed that there were severe leukocyteinfiltration in alveolar spaces, alveolar edema and destroyed alveolar structure in groupB and C. The serum TNF-u leve],W/D ratio and MDA content in the left lung and neutrophilpercentage and WBC counts in BALF were significantly higher in group C than in group B.Conclusion Clara cells can protect the lungs against I/R injury through inhibitinginflammatory responses. Key words: Reporfusion injury; Lung; Clara cell; Inflammatory reaction