Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide found in the N-terminal portion of the prohormone of adrenomedullin (AM), a vasodilator peptide. In this study, we examined the pathophysiological roles of the two peptides. Plasma concentrations of both peptides in patients with impaired renal function were measured and compared to those of the control subjects. Plasma AM concentrations in the study patients were significantly (P < 0.01) higher than in the controls with a serum creatinine of < 1 mg/dl (2.94 +/- 0.18 fmol/ml), and higher concentrations in those patients with a serum creatinine of > or = 2 mg/dl (Group II; 14.8 +/- 1.9 fmol/ml) were observed as compared to those at the 1 to 2 mg/dl level (Group I; 10.3 +/- 1.2 fmol/ml). Similarly, plasma PAMP concentrations tended to be higher in the Group I patients (0.82 +/- 0.05 fmol/ml) and significantly (P < 0.01) increased in the Group II patients (1.42 +/- 0.17 fmol/ml) when compared to the controls (0.53 +/- 0.04 fmol/ml). A significantly (P < 0.05) positive correlation was noted between the plasma AM and PAMP in the study patients. These findings suggest a potential role for these biologically active peptides in the regulation of blood pressure in impaired renal function.