AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 4 495-R500, Copyright © 1985 by American Physiological Society
Renal response to atrial natriuretic factor in conscious dogs with caval constriction
R. H. Freeman, J. O. Davis and R. C. Vari
Constriction of the thoracic inferior vena cava to decrease venous return
and atrial filling markedly elevates plasma renin activity (PRA) and plasma
aldosterone concentration (PAC) and produces chronic sodium retention and
ascites in the dog. Infusion of a synthetic atrial natriuretic factor into
conscious dogs with caval constriction and ascites at doses of 175 and 350
ng X kg-1 X min-1 for 30 min each produced striking increases (P less than
0.05) in creatinine clearance, diuresis, and kaliuresis but failed to
increase urinary sodium excretion. Infusions of atrial natriuretic factor
at these doses into conscious normal dogs, however, produced a striking
increase in sodium excretion from 41 +/- 14 and 55 +/- 19 mu eq/min to 150
+/- 58 and 181 +/- 49 mu eq/min (P less than 0.05 for both values).
Creatinine clearance and urine flow also increased in these normal dogs,
but potassium excretion remained unchanged during the infusion periods.
Atrial natriuretic factor produced parallel suppression (P less than 0.05)
of the elevated levels of PRA and PAC in the caval dogs but failed to
significantly decrease either PRA or PAC in the normal animals. Arterial
pressure, heart rate, and PAH clearance were unchanged in both groups of
dogs during infusion of atrial natriuretic factor. These results suggest
that the pattern of renal electrolyte excretion elicited in response to the
acute infusion of atrial natriuretic factor is dependent, at least
partially, on the preexisting status of the renal tubules to facilitate
sodium reabsorption and potassium excretion. The results also are
consistent with the concept that atrial natriuretic factor might function
to tonically inhibit the renin-angiotensin-aldosterone system.
