Objective To investigate the expression and role of adrenomedullin (ADM) and adrenomedullin receptor (ADMR) in patients with chronic obstructive pulmonary disease (COPD).Methods Small pulmonary artery remodeling was observed using morphometric analysis. The expression of ADM and ADMR mRNA in lung tissue was calculated by in situ hybridization in 9 COPD cases. Cardiac catheterization was performed in 22 COPD cases to monitor changes of hemodynamic parameters and patients were divided into two groups based on mean pulmonary artery pressure (mPAP). The cases without pulmonary hypertension (PH) were placed in Group A (n =12) and those with PH were placed in Group B (n =10). The levels of pulmonary arterial plasma ADM were measured by radioimmunoassay. Blood gas analysis was also conducted.Results The ratio of vascular wall thickness to external diameter (MT%) and the ratio of vascular wall area to total area (MA%) were higher in patients with COPD ( P < 0. 01). In situ hybridization showed that ADM mRNA and Objective To investigate the expression and role of adrenomedullin (ADM) and adrenomedullin receptor (ADMR) in patients with chronic obstructive pulmonary disease (COPD). Methods Small pulmonary artery remodeling was observed using morphometric analysis. The expression of ADM and ADMR mRNA in lung tissue was calculated by in situ hybridization in 9 COPD cases. Cardiac catheterization was performed in 22 COPD cases to monitor changes of hemodynamic parameters and patients were divided into two groups based on mean pulmonary artery pressure (mPAP). The cases without pulmonary hypertension (PH) were placed in Group A (n = 12) and those with PH were placed in Group B (n = 10). The levels of pulmonary arterial plasma ADM were measured by radioimmunoassay. Blood gas analysis was also conducted. Results The ratio of vascular wall thickness to external diameter (MT%) and the ratio of vascular wall area to total area (MA%) were higher in patients with COPD (P <0.01). In situ hybridization showed that ADM mRNA and