Further evidence for hepatic control of salt intake in rats

We examined the contributions of oral and hepatic factors to the control of salt intake in rats made "salt hungry" by combined dietary sodium restriction and furosemide treatment. A 7.5-ml preload of 0.5 M NaCl, which was either voluntarily ingested or slowly infused (7.5 ml/90 min) into the hepatic portal vein, decreased subsequent 0.5 M NaCl intake by approximately 7.5 ml in both cases. Hepatic portal infusions were probably acting in the liver because slow jugular infusions (7.5 ml/90 min) did not influence salt drinking, although rapid (7.5 ml/5 min) infusions by both routes reduced salt intake. If salt was ingested but drained through a gastric cannula, rats showed little sign of reducing salt in a 2-h test. These results suggest that the quantity of salt ingested by salt-hungry rats is regulated by a postabsorptive mechanism that is probably located in the liver.