Presence of the N-terminal and C-terminal portions of the prohormone of atrial natriuretic factor in the ascitic fluid of cirrhotic patients.

The simultaneous measurement of plasma and ascitic fluid N-terminal and C-terminal portions of the 126 amino acid atrial natriuretic factor (ANF) prohormone (proANF) concentrations in six cirrhotic patients revealed that the C-terminus (amino acids 99 to 126; ANF) and the N-terminus (amino acids 1 to 98) are present in high concentrations (mean = 30 +/- 2 fmol/mL and 701 +/- 43 fmol/mL, respectively) in the ascitic fluid of these patients. In addition to the whole N-terminus, the midportion of the N-terminus (amino acids 31 to 67; proANF 31 to 67) was present in ascitic fluid as a separate identity at a concentration of 711 +/- 63 fmol/mL. The concentrations of the C-terminus, proANF 31 to 67, and N-terminus in ascitic fluid were nearly equal to their concentrations in plasma (32 +/- 4 fmol/mL, 761 +/- 54 fmol/mL, and 772 +/- 54 fmol/mL, respectively). The plasma levels of the N-terminus and C-terminus in the cirrhotic patients were considerably higher than the mean plasma concentrations of these peptides in 54 persons without cirrhosis (531 +/- 25 fmol/mL, 371 +/- 22 fmol/mL, and 22 +/- 1 fmol/mL, respectively [p less than 0.05; analysis of variance (ANO-VA)]. Data demonstrate that the whole N-terminus, midportion of the N-terminus (proANF 31 to 67), and C-terminus of proANF are present in ascitic fluid in high concentrations that are nearly equal to plasma levels. This suggests that their presence in ascitic fluid is due to capillary leakage of peptides in the hepatic sinusoids.