Liver atrophy, hypertrophy and regenerative hyperplasia in the rat: the relevance of blood flow.
Liver perfusion can be measured sequentially by monitoring the clearance of 85krypton injected into the portal circulation. Preliminary studies in dogs show that the method reflects gas clearance from a homogeneously perfused liver parenchyma and correlates well with measurements of total hepatic blood flow. The method has been adapted to measurement of liver blood flow in normal rats, partially hepatectomized rats and after portacaval transposition with and without partial hepatectomy. There is a marked rise of approximately 250% in the first four hours after partial hepatectomy in the rat. After portacaval trans-position, liver blood flow remains within the normal range and no great rise occurs after partial hepatectomy. In animals subjected to portacaval transposition, there is a reduction in relative liver weight (liver weight/body weight ratio) and when partial hepatectomy is performed three weeks after portacaval transposition, the relative liver weight is regained within three weeks, and does not differ from that of non-hepatectomized controls. DNA synthetic activity, studied during the 72 hours after partial hepatectomy performed three weeks after portacaval transposition, shows an uptake of tritiated thymidine into liver DNA of the same magnitude as and contemporaneous with that of controls. Liver atrophy after portal diversion is not a result of a decrease in absolute liver blood flow. Regenerative hyperplasia appears to be independent of a direct supply of portal blood and occurs in the absence of the post-hepatectomy rise in liver blood flow seen in normal rats.