Expression Of Nitric Oxide Synthase Isoenzyme In Lung Tissue Of Smokers With And Without COPD

Background:Although cigarette smoking is the main cause of chronic obstructive pulmonary disease (COPD), only a minority of cigarette smokers develop it.Objective:To investigate the alterations of nitric oxide synthase isoforms expressions between smokers with and without COPD, which might helpful for identifying the smoker’s susceptibility to COPD.Methods:The Peripheral lung tissues were obtained from10nonsmoker control subjects,15non-COPD smokers and15smokers with COPD. Neuronal NO synthase (nNOS), inducible NO synthase (iNOS), and endothelial NO synthase (eNOS) mRNA and protein levels were measured in each sample by using real-time PCR and Western blotting.Results:iNOS mRNA was significantly increased in Patients with COPD compared with nonsmokers and smokers with normal lung function (p＜0.001). iNOS protein was also higher in COPD than nonsmokers and smokers (p<0.001and P=0.01,respectively). However, expression of nNOS and eNOS did not differ among nonsmokers, smokers with and without COPD. Furthermore, there was a negative correlation between iNOS protein level and lung function parameters FEV1(%predicted)(r=0.549, P=0.001) and FEVi/FVC (%,r=0.535, P=0.001).Conclusion:These results suggest that iNOS might be involved in the pathogenesi: COPD and associated with smokers’susceptibility to COPD.