A histochemical study of ATPase activity in the experimentally intoxicated liver has been conducted and the following results were obtained.
1. ATPase was found to be mostly distributed at the sinusoid and bile capillary regions.
2. When the liver was damaged acutely or chronically with carbon tetrachloride, necrosis of the liver cells developed. At the site of necrosis, the capillary vessels were dilated and ran irregularly and often underwent cystic transformation which were caused by the necrotic degeneration of the hepatic cells. At the intercellular spaces around the necrotic resions, a high ATPase activity was demonstrated. These changes were considered to be resulted from the compression of bile capillary vessels with hepatic cells which underwent vacuolar degeneration.
3. No significant changes in ATPase activity at the bile capillary vessels was observed in the liver which received partial resection.
4. The distribution of ATPase in the liver after theα-naphthyl isothiocyanate administration or the ligation of the bile duct suggested the presence of marked biliary obstruction. In the former, ATPase activity was found at the perilobulular regions and increased towards the periphery. On the other hand, in the latter case a marked dilatation of the capillary vessels was observed and ATPase activity was more pronoucedly increased at the cholestasis.
5. ATPase activity in the sinusoid wall appeared to be lowered at the regions where vacuolar degeneration occurred but markedly increased where the hepatic cells underwent necrosis. This tendency was particulary apparent in Kupffer's cells. ATPase activity in the sinusoid seemed to be increased slightly when the liver underwent partial resection. ATPase activity of the sinusoid markedly increased at the perilobulular regions when intoxicated with α-naphthyl isothiocyanate and increased with the lapse of time in the case of hepatic duct ligation. These changes in ATPase activity under various experimental conditions suggest that this enzyme is involved in many aspects of hepatic functions particularly in the excretion and retention of the bile. The increase of ATPase activity in Kupffer's cells is also interpreted to indicate their intimate association to their functions.
6. The increase of ATPase in Glisson's capsule at the time of chronic hepatic disorders and high ATPase activity in the fibers developed at the border plate after theα-naphthyl isothiocyanate administration strongly suggest that this enzyme plays an important role in the formation of the fibers.