The intrahepatic distribution of portal venous and arterial blood

Abstract

Summary The distribution of arterial and portal venous blood within the liver, and within the cephalad and distal areas of each liver lobe, was investigated. The working hypothesis was based on the capacity of the reticuloendothelial system (RES) lining the liver sinusoids to remove iodine 131 -labeled, heat-denaturated human serum albumin, injected directly into the hepatic artery and portal vein. The distribution was calculated as percentage dose cleared per lobe and per gram liver tissue in the cephalad and distal areas of each liver lobe. The distribution pattern and clearance efficiency values, obtained after alternate injection of each component, were used as an index for the distribution of arterial and portal venous blood at the sinusoid level. The changes in distribution and clearance efficiency after simultaneous injection and acute and chronic ligation of each component were used for the determination of the portal vein—hepatic artery relationship. Our results indicate that each component has a specific intrahepatic distribution affected only by severe changes in arterial circulation. Portal venous blood was spread evenly throughout the liver sinusoids with a slight cephalad concentration, while arterial blood was concentrated mainly in the cephalad areas. The pattern of portal venous circulation changed when hepatic arterial blood was prevented from entering the liver, whereas the pattern of arterial blood distribution was not affected by changes in portal venous flow. Clearance efficiency values increased after chronic portal vein ligation and decreased after hepatic artery ligation, implying that the arterial flow is capable of compensating for the absence of portal venous blood and constitutes the predominant component of the afferent circulation.