Diaphragm Alterations And Nitric Oxide Synthases Expression In Chronic Obstructive Pulmonary Disease

Objective Oxidative stress and nitric stress are associated with the pathophysiology of many diseases,include the chronic obstructive pulmonary disease(COPD) . The former study found However,its relationship to diaphragm injury of COPD patients has not yet been identified clearly. This study aimed to investigate the ultrastructure and histological injury of diaphragm and the changes of Nitric oxide synthases (NOS) expression, in order to assess the probalble function of nitric oxide in the diaphragm dysfunction of patients with Chronic Obstructive Pulmonary Disease (COPD),and and try to identify the probable mechanisms of diaphragm dysfunction in COPD.Method 19 male patients undergoing thoracotomy for localized lung or esophagus neoplasm were selected for the study, 12 of them with stable mild-moderate COPD and 7 with normal pulmonary function. Samples of the diaphragm were processed for electron microscopy to observe the ultrastructure injuries; immunohistochemistry determination was used to measure myosin heavy chain(MHC) isoforms expression and cross section area(CSA) of diaphragm fibers, the location of NOS expression in diaphragm was also determined by immunohistochemistry; immunoblotting measurement was used to test the expression of nitric oxide synthases(NOS) and nitro-tyrosine(NT) proteins. Meanwhile, body height, weight, body mass index were performed in order to evaluate the nutritional status of the patients, and the pulmonary function was measured before surgery.Result (1) There were ultrastructure injuries in diaphragm of patients with mild-moderate COPD: myofilaments alinement was chaotic and disrupted; Z-line streaming; A- and I-band disruption. Mitochondria were distributed as clusters, some were accompanied by medulla-like degeneration; (2) The proportions of MHC isoforms were no significant differences between the two groups(P>0.05); (3) The diaphragm cross section area(CSA) of the different MHC isoforms were no differences between the two groups, but when taken the moderate COPD patients as a single group, the CSA of muscles which expressed MHCslow were decreased significantly compared with the control group(P<0.05); (4) Compared with the control group, MHC protein expression in COPD group was significantly lower (P<0.05),and it was positively correlated with FEV1% predicted; (5) Compared with the control group, nNOS and iNOS were significantly higher in COPD group (P<0.05), and eNOS expression had no change between the two groups(P>0.05); (6) Nitro-tyrosine(NT) expression was significantly higher(P<0.05)when compared with the control group; (7) The three NOS isoforms and NT were inversely correlated with FEV1% predicted.Conclusion In the early stage of COPD patients, diaphragm experienced a series of ultrastructure injuries, and there was a trend of atrophy in diaphragm muscle fibers. On the other hand, endogenous NOS of diaphragm was increased significantly, which induced the increase of nitrate tyrosine, the latter one was a sign of protein tyrosine nitration in diaphragm of COPD patients, which made the structure and function of diaphragm proteins impaired. The changes of these two aspects probably together contribute to diaphragm dysfunction in the early stage of COPD patients.