The N-terminus and a 4,000-MW peptide from the midportion of the N-terminus of the atrial natriuretic factor prohormone each circulate in humans and increase in congestive heart failure.
Two peptides consisting of amino acids 1-30 and 31-67 of the N-terminus of the prohormone of atrial natriuretic factor (pro-ANF) that have vasodilatory and natriuretic properties were investigated to determine if they circulate in humans. Specific and sensitive radioimmunoassays were developed to amino acids 1-30, 31-67, and 99-126 of pro-ANF. Evaluation of human plasma that had been subjected to reverse-phase high-pressure liquid chromatography suggested that pro-ANFs 1-30 and 31-67 as well as ANF were distinct peaks in human plasma corresponding exactly to pure synthetic peaks of these peptides on high-pressure liquid chromatography. Molecular weight determination of the endogenous immunoreactive peptides measured in plasma by G-50 Sephadex gel permeation chromatography revealed that the pro-ANF 1-30 radioimmunoassay recognized a peptide of 10,000 MW, which is consistent with it measuring the whole N-terminus of pro-ANF (amino acids 1-98) but without ANF (C-terminus) attached to it. The pro-ANF 31-67 radioimmunoassay recognized mainly (more than 95%) a peptide of 3,900-4,000 MW, which corresponds closely with its actual molecular weight of 3,878. Our ANF radioimmunoassay recognizes a peptide in plasma of 3,000 MW with the known molecular weight of ANF being 3,081. The mean circulating concentrations of immunoreactive pro-ANF 1-98, pro-ANF 31-67, and ANF in 54 control subjects were 531 +/- 25, 371 +/- 18, and 22 +/- 1 fmol/ml (+/- SEM), respectively. Thirty patients with varying severity of congestive heart failure were also studied. The N-terminus, C-terminus, and pro-ANF 31-67 increased: twofold for New York Heart Association functional Class II, threefold to ninefold for Class III, and 10- to 20-fold for Class IV patients with congestive heart failure. Thus, the N-terminus and a 4,000-MW peptide from the midportion of the N-terminus of pro-ANF as well as ANF circulate normally and increased proportionately to the increasing severity of congestive heart failure. However, because the pro-ANF 31-67 radioimmunoassay was the only assay that discriminated between patients with Class I congestive heart failure and control subjects, this assay may be the most useful to accurately classify the severity of congestive heart failure.
Winters
C J
CJ
Sallman
A L
AL
Baker
B J
BJ
Meadows
J
J
Rico
D M
DM
Vesely
D L
DL
D000328:Adult; D009320:Atrial Natriuretic Factor / Q000097:blood* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010446:Peptide Fragments / Q000097:blood* / Q000302:isolation & purification; D010454:Peptide Termination Factors / Q000097:blood* / Q000302:isolation & purification; D011498:Protein Precursors / Q000097:blood* / Q000302:isolation & purification; D011863:Radioimmunoassay / Q000379:methods; D014883:Water-Electrolyte Imbalance / Q000097:blood
D010446:Peptide Fragments; D010454:Peptide Termination Factors; D011498:Protein Precursors; C054547:atrial natriuretic factor prohormone (1-30), human; C054548:atrial natriuretic factor prohormone (31-67); C055659:atrial natriuretic factor prohormone (1-98); D009320:Atrial Natriuretic Factor