AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 5 1057-R1067, Copyright © 1989 by American Physiological Society
Heterogeneous renal responses to atrial natriuretic factor. I. Chronic caval dogs
E. Maher, P. Cernacek and M. Levy
Department of Physiology, McGill University, Montreal, Quebec, Canada.
Atrial natriuretic factor (ANF) (175 ng.kg-1.min-1) was administered to 14
normal, alert dogs and again after constriction of the thoracic vena cava.
The average natriuresis observed in the dogs when they were normal was
blunted by 55% when they developed ascites and were avidly retaining
sodium. Of the 14 caval dogs, 7 showed a natriuretic response no different
from the control phase while 7 showed no natriuresis at all in response to
the ANF. Ten dogs were restudied when they entered a phase of sodium
balance despite the persistence of ascites. All 10 dogs now responded to
ANF, and 5 dogs previously not responding now showed a mean change of
urinary sodium excretion rate (delta UnaV) of 204 mu eq/min. The two groups
could not be differentiated in terms of plasma volume, systemic or renal
hemodynamics, or plasma levels of renin and aldosterone. We conclude that
there is reversible attenuation of the ANF natriuretic effect in 50% of
chronic caval dogs, which disappears when they lose avidity for sodium
retention.
