Increase in the plasma levels of the N-terminal and C-terminal portions of the prohormone of atrial natriuretic factor during normal pregnancy.
The influence of pregnancy on the circulating concentrations of atrial natriuretic factor, the 28 amino acid carboxy (C)-terminal end of the 126 amino acid atrial natriuretic factor prohormone, and the amino (N)-terminus of the prohormone was studied with three specific radioimmunoassays recognizing: (1) atrial natriuretic factor (i.e., amino acids 99 through 126), (2) the 98 amino acid N-terminus, and (3) amino acids 31 through 67 from the midportion of the N-terminus of the prohormone. Plasma atrial natriuretic factor in normal pregnant women gradually increased as pregnancy progressed, with the mean +/- SEM being 58 +/- 4 pg/ml in the first trimester, 74 +/- 5 pg/ml in the second trimester, and 89 +/- 7 pg/ml in the third trimester. Likewise, proatrial natriuretic factor 31 through 67 increased from 1421 +/- 76 pg/ml (first trimester) to 1509 +/- 84 pg/ml (second trimester) to 1758 +/- 83 pg/ml in the third trimester, whereas the whole N-terminus of the prohormone increased from 1804 +/- 98 pg/ml (first trimester) to 1909 +/- 111 pg/ml (second trimester) to 2160 +/- 79 pg/ml in the third trimester. These results suggest that release of the N-terminus of the prohormone, as well as atrial natriuretic factor, increases with the rise in blood volume associated with a normal pregnancy. The circulating concentrations of both the C-terminus and N-terminus of the atrial natriuretic factor prohormone increased further in the 48 hours after delivery. Because both the C-terminus and N-terminus of the atrial natriuretic factor prohormone contain diuresis-producing peptides, these results suggest that postpartum diuresis may be mediated by these peptides.
Merkouris
R W
RW
Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock 72205.
Miller
F C
FC
Catanzarite
V
V
Rigg
L A
LA
Quirk
J G
JG
Vesely
D L
DL
D000704:Analysis of Variance; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001794:Blood Pressure; D001835:Body Weight; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D006339:Heart Rate; D006801:Humans; D007743:Labor, Obstetric / Q000097:blood; D009318:Natriuresis; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000097:blood*; D011247:Pregnancy / Q000097:blood*; D011263:Pregnancy Trimester, Third; D011498:Protein Precursors / Q000097:blood*; D011863:Radioimmunoassay; D012016:Reference Values
D010446:Peptide Fragments; D011498:Protein Precursors; D009320:Atrial Natriuretic Factor