AJP - Endocrinology and Metabolism, Vol 252, Issue 2 E279-E282, Copyright © 1987 by American Physiological Society
Atrial natriuretic factor in maternal and fetal sheep
C. Y. Cheung, D. M. Gibbs and R. A. Brace
To determine atrial natriuretic factor (ANF) concentrations in the
circulation and body fluids of adult pregnant sheep and their fetuses,
pregnant ewes were anesthetized with pentobarbital sodium, and the fetuses
were exteriorized for sampling. ANF concentration, as measured by
radioimmunoassay, was 47 +/- 6 (SE) pg/ml in maternal plasma, which was
significantly higher than the 15 +/- 3 pg/ml in maternal urine. In the
fetus, plasma ANF concentration was 265 +/- 49 pg/ml, 5.6 times that in
maternal plasma. No umbilical arterial and venous difference in ANF
concentration was observed. Fetal urine ANF concentration (13 +/- 2 pg/ml)
was significantly lower than that in fetal plasma, and was similar to that
measured in amniotic and allantoic fluid. In chronically catheterized
maternal and fetal sheep, fetal plasma ANF was again 5.1 times that in
maternal plasma, and these levels were not different from those measured in
acutely anesthetized animals. These results demonstrate that immunoreactive
ANF is present in the fetal circulation at levels higher than those found
in the mother. The low concentration of ANF in fetal urine suggests that
ANF is probably metabolized and/or reabsorbed by the fetal kidney.
