ENDOTHELIAL DYSFUNCTION IN PULMONARY-ARTERIES OF PATIENTS WITH MILD COPD

To investigate whether endothelial dysfunction of pulmonary arteries ( PA) is present in patients with mild chronic obstructive pulmonary dis ease (COPD) and to what extent it is related to the morphological abno rmalities of PA, we studied 41 patients who underwent lung resection. Patients were divided into the following groups: nonsmokers (n = 7), s mokers with normal lung function (n = 13), and COPD (n = 21). Endothel ium-dependent relaxation mediated by nitric oxide was evaluated in vit ro in PA rings exposed to cumulative concentrations of acetylcholine ( ACh) and ADP. Structural abnormalities of PA were assessed morphometri cally. PA of COPD patients developed lower maximal relaxation in respo nse to ADP than both nonsmokers and smokers (P < 0.05 each) and a tren d to reduced relaxation in response to ACh (P = 0.08). Maximal relaxat ion to ADP correlated with the degree of airflow obstruction (r = 0.48 , P < 0.01). Morphometrical analysis of PA revealed thicker intimas, e specially in small arteries, in both smokers and COPD compared with no nsmokers (P < 0.05 each). We conclude that endothelial dysfunction of PA is already present in patients with mild COPD. In these patients, a s well as in smokers with normal lung function, small arteries show th ickened intimas, suggesting that tobacco consumption may play a critic al role in the pathogenesis of pulmonary vascular abnormalities in COP D.