Heterogeneous renal responses to atrial natriuretic factor. II. Cirrhotic dogs

The renal response to atrial natriuretic factor (ANF) (175 ng.kg-1.min-1) was tested in nine dogs during a control period and again after the appearance of experimental cirrhosis, ascites, and avid sodium retention. During the cirrhotic phase, plasma volume had increased by 28.4% (P less than 0.05), renal perfusion and glomerular filtration rate (GFR) were unchanged from control values, and plasma immunoreactive ANF (iANF) had declined from 71.6 +/- 9.5 to 34.7 +/- 5.4 pg/ml (P less than 0.05). During the control phase, change of urinary sodium excretion rate (delta UNaV) increased by 132 +/- 22 mu eq/min but was attenuated in the cirrhotic phase (delta UNaV = 29 +/- 12.5 mu eq/min). Of these nine cirrhotic dogs, five responded with a delta UNaV ranging from 20 to 114 mueq/min (mean delta UNaV = 59.6 +/- 10.6 mu eq/min), whereas 4 were nonresponders (delta UNaV = 1.3 +/- 0.6 mu eq/min). In neither group could delta UNaV be correlated to changes in GFR, clearance of p-aminohippurate, or filtration fraction. In an additional 10 dogs studied only during cirrhosis, 5 were natriuretic responders and 5 were nonresponders. Atrial content of ANF, half time of infused ANF, and plasma levels of iANF did not differentiate the two groups. We conclude that, like chronic caval dogs with ascites, salt-retaining cirrhotic dogs show heterogeneity of natriuretic response to infused ANF, which is unexplained by differences in renal perfusion.