Evidence for an Hepatic Role in the Control of Sodium Excretion

The increased natriuresis found after a small hypertonic sodium chloride load was infused into anesthetized dogs was found to be greater when the stimulus was administered directly into the hepatic circulation than when it was infused systemically via the femoral vein. In addition, the response appears to be dose-related within limits. At 0.05 ml/kg/min a significant natriuresis was obtained only after portal loading. At double this rate, significant increases in sodium excretion occurred with both routes of administration, but the increase after portal loading was more than 50% greater. At a higher rate of infusion (0.4 ml/kg/min) no difference was observed between routes. It would appear that the liver exerts a modest influence on sodium excretion and that the modest contribution of an hepatic component is obscured by other components of the natriuretic response to saline loading when the load of saline is increased.