Some properties of alkaline-phosphatases in parenchymal and biliary tract cells separated from rat liver.

Livers of both normal and bile-duct ligated rats have been separated into parenchymal cells and fractions enriched in biliary tract cells. The specific activity of alkaline phosphatase increases in both types of cells after occlusion of the bile duct but the increase is more marked in the case of parenchymal cells. The enzyme from parenchymal cells migrates as a single zone on electrophoresis, whereas additional zones of lower anodal mobility occur in extracts of biliary tract preparations. The alkaline phosphatase activity of the slower zones is significantly less stable to heat than that of the zone characteristic of parenchymal cells. It is postulated that the increase in heat stability of alkaline phosphate in extracts of whole rat liver after bile-duct ligation is due to an increase in the proportion of the more stable form of the enzyme predominant in parenchymal cells.