AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 5 947-R956, Copyright © 1986 by American Physiological Society
Control of atrial natriuretic factor release in conscious dogs
K. M. Verburg, R. H. Freeman, J. O. Davis, D. Villarreal and R. C. Vari
The aim of this study was to examine the changes in the concentration of
plasma immunoreactive atrial natriuretic factor (iANF) that occur in
response to expansion or depletion of the extracellular fluid volume in
conscious dogs. The plasma iANF concentration was also measured
postprandially after the ingestion of a meal containing 125 meq of sodium.
Postprandial plasma iANF increased 45% (P less than 0.05) above the
base-line concentration, and this increase was accompanied by a brisk
natriuresis. After a low-sodium meal, however, plasma iANF and sodium
excretion failed to increase. The plasma iANF concentration increased from
57 +/- 5 to 139 +/- 36 pg/ml (P less than 0.05) immediately after volume
expansion with intravenous isotonic saline infusion (2.5% body wt)
administered over a 30-min period; plasma iANF remained elevated at 90 +/-
14 pg/ml (P less than 0.05) for an additional 30 min before returning
toward preinfusion levels. Plasma iANF decreased 45% from 78 +/- 17 to 43
+/- 7 pg/ml (P less than 0.05) in response to the administration of
ethacrynic acid (2.0 mg/kg, iv bolus) that produced an estimated 15%
depletion of intravascular volume. In additional experiments the infusion
of synthetic alpha-human ANF at 100 and 300 ng X kg-1 X min-1 increased (P
less than 0.05) both the plasma iANF concentration and the urinary
excretion of iANF. This study demonstrates that the secretion of ANF is
consistently influenced by changes in the extracellular fluid volume.
Furthermore, the results support the concept that ANF functions to increase
postprandial sodium excretion following the ingestion of a high-sodium
meal.
