Immunoreactive amino terminal pro atrial natriuretic peptide in human plasma plasma levels and comparisons with alpha human atrial natriuretic peptide in normal subjects patients with essential hypertension cardiac transplant and chronic renal failure
Bruckley, M.G.; Sagnella, G.A.; Markandu, N.D.; Singer, D.R.J.; Macgregor, G.A.
Clinical Science 77(5): 573-579
ISSN/ISBN: 0143-5221 Accession: 007431658
1. Plasma levels of immunoreactive N-terminal proatrial natriuretic peptide (N-terminal ANP) have been measured in 25 normal subjects, 29 patients with essential hypertension, six cardiac transplant recipients, seven patients with dialysis-independent chronic renal failure and 11 patients with haemodialysis-dependent chronic renal failure. Plasma was extracted on Sep-Pak cartridges and N-terminal ANP immunoreactivity was measured using an antibody directed against por-ANP (1-30). 2. Plasma levels of N-terminal ANP (means .+-. SEM) were 235.3 .+-. 19.2 pg/ml in normal subjects and were significantly raised in patients with essential hypertension (363.6 .+-. 36.3 pg/ml), in cardiac transplant recipients (1240.0 .+-. 196.2 pg/ml), in patients with chronic renal failure not requiring dialysis (1636.6 .+-. 488.4 pg/ml) and patients with chronic renal failure on maintenance haemodialysis (10336.1 .+-. 2043.7) pg/ml). 3. There were positive and significant correlations between the plasma levels of N-terminal ANP and .alpha.-human ANP (.alpha.-hANP) with individual correlation coefficients of 0.68 within the normal subjects, 0.47 in patients with essential hypertension, 0.78 in patients with dialysis-independent chronic renal failure and 0.68 in patients with haemodialysis-dependent chronic renal failure (P < 0.05 in every case). 4. Gel filtration behaviour on Sephadex G-50 of the immunoreactive N-terminal ANP from Sep-PAK extracts of plasma from normal subjects or patients was consistent with a single peak having an elution volume corresponding to that of human pro-ANP (1-67) standard. 5. These studies demonstrate that the N-terminal pro-ANP peptide is co-secreted with .alpha.-hANP in both normal subjects and patients with cardiovascular/renal disease. The higher levels of the N-terminal ANP may reflect differences in the rate of elimination from the circulation but the exact structure and functional significance of the circulating N-terminal ANP remains to be established.