Immunoreactive N-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.

1. Plasma levels of immunoreactive N-terminal pro-atrial 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 pro-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 less than 0.05 in every case).(ABSTRACT TRUNCATED AT 250 WORDS)