Different behaviour of the N-terminal and C-terminal fragment of proatrial natriuretic factor in plasma of healthy subjects as well as of patients with cirrhosis

N-terminal (atrial natriuretic factor (ANF) 1-98) and C-terminal (ANF 99-126) fragments of proatrial natriuretic factor (NTA and CTA, respectively) were determined in plasma of healthy subjects adopting different postures and in patients with cirrhosis. Seven healthy subjects were investigated while seated and 30 min after assuming a horizontal position. NTA plasma concentrations increased in subjects in the horizontal position (from 734 +/- 250 (SE) fmol/ml to 902 +/- 227 fmol/ml; p less than 0.05). In contrast, CTA plasma concentrations remained unchanged (9.2 +/- 1.3 fmol/ml vs 8.9 +/- 1.6 fmol/ml). In 10 patients with cirrhosis of the liver, NTA concentrations were markedly (p less than 0.001) elevated compared to 11 healthy subjects (2334 +/- 291 fmol/ml vs 743 +/- 155 fmol/ml). However, there was no difference of CTA plasma levels between cirrhotic patients and healthy subjects (8.7 +/- 1.3 fmol/ml vs 8.2 +/- 0.9 fmol/ml). These data demonstrate changes of the plasma concentration of the N-terminal fragment of proatrial natriuretic factor by posture and in liver disease, in contrast to unchanged levels of the C-terminal fragment.