The evidence of production or activation of a natriuretic factor in the liver

The natriuretic activity was measured with the aid of bioassay in blood flowing out from the brain, kidney and liver before and after the expansion of extracellular space in dogs. In another experiments in rats the volume natriuresis and the natriuretic activity in blood were measured in controls and in animals with carbon tetrachloride liver dystrophy and pharmacological stimulation (dehydrocholic acid, Ca pantothenate, cyanocobalamin) of liver functions. In dogs, the level of natriuretic activity in blood flowing out of the liver before and after the expansion of extracellular fluid volume was significantly higher than that in arterial blood. In contrast, the natriuretic activity was not found in the blood flowing out of the brain and the kidney. In rats the experimental dystrophy of the liver decreased the content of a natriuretic factor in blood plasma and the expansion of extracellular space did not produce any natriuretic effect as compared to control rats. After pharmacological stimulation of the liver by dehydrocholic acid, Ca pantothenate and cyanocobalamine the volume expansion led to a significant increase of the excretion of sodium by the kidney and to the increase of the content of a natriuretic factor in blood plasma as compared to control rats. These facts are considered to support the view that a natriuretic factor is either synthesized or activated by the liver.