[Pulmonary vascular remodeling is prior to the increase in pulmonary hypertension of chronic obstructive pulmonary disease].

Objective: To explore the remodeling of pulmonary arterioles in chronic obstructive pulmonary disease (COPD), and its effect on hemorheology of proximal pulmonary arteries, right ventricular structure and function , and the potential mechanisms. Method: A total of 34 patients undergoing surgical treatment for lung tumors admitted to the General Hospital of Ningxia Medical University were included in the study. According to the preoperative lung function, there were 15 patients with COPD complicated with lung tumor (COPD group) and 19 patients with normal pulmonary function with lung tumor (control group). All patients underwent cardiac nuclear magnetic resonance (CMR) before surgery, and the hemorheology of the proximal pulmonary arteries, right ventricular structure and function were obtained by CMR. The normal lung tissues distal to the tumor lesion were taken during the operation, and the morphological changes of the pulmonary arterioles were observed by hematoxylin-eosin staining and Weigert-van Gieson. Immunohistochemistry was used to detect the location and expression of α-smooth muscle actin(SMA) and proliferating cell nuclear antigen(PCNA) in pulmonary arterioles, and the expression of protein and mRNA of α-SMA in lung tissue was detected by Western-blotting and real-time quantitative PCR. Results: The results of CMR showed that mPAP was not statistically different between COPD group and control group (24.0±3.7 vs 22.8±1.6, P>0.05). The main pulmonary artery distensibility (mPAD%), right ventricular myocardial mass end-diastolic (RVMED), right ventricular myocardial mass end-systolic (RVMES), average negative flow(ANF) and regurgitant fraction(RF%) were statistically different between COPD group and control group (P<0.05). The wall thickness (WT), WT% and WA% were significantly higher in COPD group [(37±18) µm, (65±19)% and (55±23)%, respectively] than in control group [(19±3 )µm, (29±5)% and (40±7)%, respectively]. The number of pulmonary arterial smooth muscle cells per unit area and smooth muscle cell proliferation rate were significantly higher in COPD group than in the control group(P<0.01). The expression of α-SMA protein and mRNA in COPD group was higher than that in control group(P<0.05). WA% and WT% were correlated inversely with mPAD%, but positively with RVMES, RVMED and RF%. Conclusions: Pulmonary vascular remodeling and rheological changes, even right heart myocardial structural changes, were observed in COPD patients without pulmonary arterial hypertension. Pulmonary arteriolar remodeling can affect the main pulmonary arterial hemorheology in COPD patients and further affect the myocardial structure of right heart. Pulmonary arterial remodeling may be a new direction for the clinical treatment of COPD.

[The mechanism of nicotine on human bronchial smooth muscle cell contraction].

Objective: To investigate the molecular mechanism of contractility dysfunction of human bronchial smooth muscle cells induced by nicotine. Methods: Primary human bronchial smooth muscle cells were cultured in vitro. The cells were divided into a control group and a nicotine group which was treated with 10(-5) mol/L nicotine for 48 h and transfected with or without α7nAChR-siRNA (The siNC group, siNC + nicotine group and siα7nAChR + nicotine group). The effects of nicotine on the cell contractile function were examined by collagen gel shrinkage assay. The expressions of α7nAChR and TRPC6 protein in nicotine-treated human bronchial smooth muscle cells were detected by Western blotting. The change of intracellular calcium concentration by nicotine was detected by calcium ion imaging system.Data were analyzed by t test or single factor analysis of variance. Results: The area of collagen gel in the nicotine group (24±8)% was significantly lower than that in the control group (59±14)% (t=3.78, P<0.05). Compared with the control group, the expression of α7nAChR protein in nicotine-induced group (173±16)% was significantly higher than that of controls 100±0)%, t=-6.848, P<0.05. Compared with the siNC group [(72±10)%, (0.79±0.07), (0.41±0.04) and (0.17±0.02) respectively], the collagen gel area of siNC + nicotine group was significantly reduced by (37±10)%. However, the basal calcium level (1.04±0.02), store operated calcium entry level (SOCE, 0.68±0.03) and receptor operated calcium entry level (ROCE, 0.36±0.02) were remarkably elevated in the nicotine treated group (all P<0.05). Furthermore, compared with siNC + nicotine group, the area of collagen gel in siα7nAChR + nicotine group was significantly increased (62±10)%, and the basal calcium level (0.78±0.06), SOCE level (0.39±0.05) and ROCE level (0.15±0.02) were significantly reduced (all P<0.05). Conclusions: Nicotine can increase the expression of TRPC6 protein, SOCE and ROCE level, and increase the intracellular calcium concentration by upregulating the expression of α7nAChR protein, thereby promoting smooth muscle cell contraction.