Response of renal nerve activity to high NaCl food intake in dogs with chronic bile duct ligation

Abstract

Hepatic sensory systems are thought to play an important role in the response of renal nerve activity and natriuresis to oral NaCl load. In this study, responses of renal nerve activity and urinary Na+ and Cl- excretions to a high-NaCl food intake (20 g/kg boiled rice containing 0.4 g/kg NaCl) were examined in sham-operated dogs (n = 12) and dogs with chronic bile duct ligation (CBDL; n = 10). In sham-operated dogs, renal nerve activity gradually decreased and reached minimal value (50% +/- 7% of the control value) at 100 minutes after the high-NaCl food intake and remained depressed until 4 hours after the food intake. Of the orally administered sodium and chloride, 27% +/- 5% and 23% +/- 6% were excreted over the following 4 hours, respectively. In CBDL dogs, the decrease in renal nerve activity induced by the high-NaCl food was completely abolished and only 4% +/- 1% of the loaded Na+ and 3% +/- 2% of the loaded Cl- were excreted. Furthermore, liver tissue norepinephrine concentration in CBDL dogs decreased to 21% of that of sham-operated dogs. These results suggest that (1) In CBDL dogs, the decrease in renal nerve activity induced by a high-NaCl food is completely abolished, probably because of the impairment of hepatic neural regulation. (2) The lack of renal nerve response may contribute, at least in part, to the abnormalities in body fluid homeostasis in cirrhosis.