Expression and role of adrenomedullin and its receptor in patients with chronic obstructive pulmonary disease

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 ADMR mRNA were expressed in the pulmonary artery walls of control subjects. The expression levels were significantly higher in those of COPD sufferers ( P < 0. 01 ).Statistically positive relationships were visible between ADM and ADMR, and the plasma ADM level of Group B was significantly higher than that of Group A (P < 0. 05). The plasma ADM level had a significantly positive correlation to mPAP and pulmonary vascular resistance (PVR), while being negatively correlated to levels of PaO2.Conclusion ADM may play an extremely protective role as a local autocrine/paracrine factor in COPD.