Hepatotrophic effect of portal blood during hepatic arterial recirculation.

Portal branch ligation (PBL) is known to induce a rapid and progressive atrophy in the liver parenchyma without portal blood flow and compensatory hyperplasia in the segments receiving the whole portal flow. In this study, the hepatotrophic effect of portal blood was studied in rats with PBL and after this procedure was combined with different portosystemic shunts. After 2 weeks, the most severe atrophy was found in ligated lobes of rats with PBL alone. In shunted animals, the atrophy was significantly inhibited and in relation to the magnitude of portal flow bypassed the liver. This suggests that in shunted rats, the portal-bone hepatotrophic factors undergo systemic recirculation and affect the liver by way of the hepatic artery. Simultaneously, in PBL + shunt rats, the rate of atrophy normally induced by a shunt was also dependent on the amount of portal blood available to this part of the liver. By a balance between these 2 processes, the total liver mass was maintained at the level found in sham PBL + shunt control rats.