Masako Iwamoto

Comparison of Plasma levels of mature adrenomedullin and natriuretic peptide as markers of cardiac function in hemodialysis patients with coronary artery disease

Background: It has been suggested that, like ANP and BNP, high plasma levels of mature adrenomedullin (mAM) indirectly reflect the severity of heart failure or renal failure. However, the relationship between mAM levels and hemodynamics and cardiac function has not been examined in hemodialysis (HD) patients with coronary artery disease (CAD). The best marker, among mAM, ANP and BNP, for left-ventricular function in those patients is also unclear. Patients and Methods: Plasma levels of mAM, total AM (tAM), ANP and BNP were determined before HD in chronic HD patients with CAD (group 1; n = 17) and were compared with those of HD patients without cardiac disease (group 2; n = 22). We examined their relationship to hemodynamics and cardiac function in group 1 using data obtained by cardiac catheterization. Results: Plasma levels of ANP and BNP were significantly higher in group 1 than in group 2, but there was no significant difference in plasma levels of mAM and tAM between the two patient groups. Plasma levels of both mAM and tAM significantly correlated with right atrial pressure (RAP), and only plasma tAM levels correlated with pulmonary artery pressure (PAP) and pulmonary artery wedge pressure (PAWP). However, no correlations were found between levels of the two forms of AM and ejection fraction (EF). In contrast, plasma ANP and BNP levels significantly correlated with both PAP and PAWP, and also with EF, although they did not correlate with RAP. The correlation of PAP and PAWP with ANP and BNP levels was closer than that with tAM levels. The most significant correlation was between BNP levels and EF (r = –0.756, p < 0.0001). Conclusions: Our results suggest that the mAM level may be less useful than natriuretic peptide levels as a marker of cardiac function in HD patients with CAD, and that the BNP level might be the best indicator of left-ventricular function. In addition, cardiac disease such as CAD may have a minor impact on mAM levels compared to renal failure.

The mature form of adrenomedullin correlates with brain natriuretic peptide in plasma of chronic hemodialysis patients

AIMnAdrenomedullin (AM), a hypotensive and natriuretic peptide, consists of an amidated mature form (mAM) and an intermediate form in human plasma, of which only mAM exerts biological activity. Like atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), plasma levels of mAM are reported to be significantly elevated in hemodialysis (HD) patients, suggesting that mAM may be stimulated partly by increased body fluid volume in a manner similar to the natriuretic peptides. Here, we examined the relationship between mAM levels and ANP or BNP levels and the effect of HD on plasma mAM in HD patients.nnnPATIENTS AND METHODSnWe measured plasma levels of mAM, total AM (tAM), ANP and BNP before and after HD in patients on long-term HD (n = 22, mean age 56.3 +/- 3.2 years) using radioimmunoassay.nnnRESULTSnBaseline mAM (2.7 +/- 0.3 fmol/ml) and tAM (23.6 +/- 2.0 fmol/ml) were significantly higher in HD patients than in healthy subjects (1.1 +/- 0.2 fmol/ml, 9.0 +/- 2.1 fmol/ml, respectively). HD significantly reduced the levels to 1.2 +/- 0.2 fmol/ml and 13.8 +/- 1.4 fmol/ml, respectively, although tAM levels were still elevated compared to healthy subjects. Similar plasma ANP and BNP levels were obtained in HD patients. There were significant correlations between mAM and tAM levels before and after HD and between HD-induced changes in mAM and tAM levels. In the pre-HD state, levels of both mAM and tAM correlated significantly with BNP levels, but the correlation of BNP with mAM was closer than that with tAM. In contrast, no correlations were observed between the 2 forms of AM and ANP. Changes in mAM levels during HD also correlated significantly with BNP but not ANP levels, although the changes in tAM did not correlate with those of the 2 natriuretic peptides.nnnCONCLUSIONnOur results suggest that the secretion/metabolism of mAM may be regulated in a manner similar to that of BNP in HD patients.