AJP - Renal Physiology, Vol 258, Issue 6 1490-F1496, Copyright © 1990 by American Physiological Society
Physiological features of edematous dogs unresponsive to atrial natriuretic peptide
E. Maher, P. Cernacek and M. Levy
Department of Physiology, McGill University, Montreal, Quebec, Canada.
Sodium-retaining cirrhotic and chronic caval dogs with ascites show a
heterogeneous natriuretic response to atrial natriuretic factor (ANF)
infusions such that half will increase their urinary excretion of sodium
and half will show no natriuretic response whatsoever. In these studies we
have examined several physiological variables that might discriminate
between these two experimental populations. We studied 22 caval dogs (11
natriuretic responders, 11 nonresponders) and 19 cirrhotic dogs (9
responders, 10 nonresponders). After an infusion of rat ANP-(1-28), 125
ng.kg-1.min-1, differences in glomerular filtration rate, blood pressure,
or urinary excretion of guanosine 3',5'-cyclic monophosphate (cGMP) could
not differentiate between the two types of dogs. When the left kidney of
nonresponding dogs in both the caval and cirrhotic groups was either
denervated or vasodilated with acetylcholine bromide (60-80
micrograms/min), the attenuation of the natriuretic response to ANF was not
reversed. Papillary plasma flow (PPF) after ANF infusion was measured by a
Lillienfield technique and averaged 36 +/- 4 ml.min-1.100 g-1 in normal
dogs, 10.7 +/- 0.7 ml.min-1.100 g-1 in both responding and nonresponding
caval dogs, and 48.3 +/- 1.1 ml.min-1.100 g-1 for each group of cirrhotic
dogs. We conclude that differences in renal perfusion, PPF, cGMP
generation, or the presence of intact renal nerves cannot explain the lack
of a post-ANF natriuretic response in half of caval or cirrhotic dogs.
Other physiological determinants must explain the heterogeneity of
natriuretic response to ANF observed in edematous dogs.
