Hepatorenal reflex plays an important role in natriuresis after high-NaCl food intake in conscious dogs.
Responses of renal nerve activity and urinary Na+ and Cl- excretion were examined in chronically instrumented conscious dogs through feedings of boiled rice with or without NaCl. The boiled rice (20 g/kg body wt) without NaCl did not influence plasma Na+ and Cl- concentrations, renal nerve activity, or urinary Na+ excretion but decreased urinary Cl- excretion. On the other hand, boiled rice containing NaCl (0.4 g/kg body wt) increased plasma Na+ (+3.8 +/- 0.7 meq/l) and Cl- (+3.0 +/- 1.5 meq/l) concentrations, then decreased renal nerve activity by 61 +/- 4%, and increased urinary Na+ and Cl- excretions. In dogs with hepatic denervation, a decrease in renal nerve activity, which was observed in intact dogs in response to the high-NaCl food intake, was completely abolished along with significant attenuation of postprandial natriuresis. That is, only 9 +/- 5% of the loaded Na+ and 7 +/- 3% of the loaded Cl- were excreted during 4 consecutive hours in hepatic-denervated dogs, whereas 36 +/- 5% of the loaded Na+ and 36 +/- 4% of the loaded Cl- were excreted in intact dogs. In dogs with renal denervation, postprandial natriuresis was also attenuated. These results indicate that the high-NaCl food intake elicits a decrease in renal nerve activity, the decrease is predominantly mediated by the hepatic nerves, and the decrease in renal nerve activity plays an important role in augmentation of urinary Na+ and Cl- excretion. Thus, the hepatorenal reflex may play an important role in controlling extracellular fluid homeostasis during food intake.
Morita
H
H
Department of Physiology, Kagawa Medical School, Japan.
Matsuda
T
T
Furuya
F
F
Khanchowdhury
M R
MR
Hosomi
H
H
D000818:Animals; D001794:Blood Pressure; D002712:Chlorides / Q000652:urine; D003714:Denervation; D004285:Dogs; D005260:Female; D006339:Heart Rate; D007668:Kidney / Q000294:innervation*; D008099:Liver / Q000294:innervation*; D009318:Natriuresis / Q000502:physiology*; D009431:Neural Conduction; D012018:Reflex; D012982:Sodium, Dietary / Q000378:metabolism* / Q000652:urine
D002712:Chlorides; D012982:Sodium, Dietary