Intrahepatic distribution of portal and hepatic arterial blood flows in anaesthetized cats and dogs and the effects of portal occlusion, raised venous pressure and histamine.

1. Radioactive microspheres were used to determine the distribution of arterial and portal flows within the liver. (141)Ce-microspheres and (51)Cr-spheres were given to allow two determinations of flow distribution in each animal and experiments are described to establish the accuracy and validity of the method.2. Mean flow/g to any lobe or segment of a lobe in a group of animals was not markedly different from the mean flow/g to the whole liver, and in general the liver was homogeneously perfused with both portal and arterial blood. However, in any one liver, some areas received a relatively greater flow (up to 300%) and some a relatively smaller flow (down to 50%) at the time the microspheres were given. The gall bladder received a much smaller portal flow/g than the parenchyma but its arterial flow/g varied widely in different animals.3. If portal flow to an area of parenchyma was reduced by occlusion of a branch of the portal vein, this area received a significantly increased arterial flow.4. An increase in hepatic venous pressure did not cause a significant change in the intrahepatic distribution of either arterial or portal flows in cats.5. In dogs, infusions of histamine into the portal vein caused a redistribution of portal flow away from the free ends of the lobes towards the hilar ends but the distribution between lobes did not change and there was no redistribution of arterial flow.