53 LOCALIZATION OF XANTHINI DEHYDROGENASE IN LIVER

Xanthine dehydrogenase has been reported to be present in an endothelial cell in beef or rat liver and also in peroxisome of a hepatic cell. However, as the most enzyme was recovered in 100,000xg supernatant of rat or chicken liver homogenate, cellular and subcellular localization in liver are still obscure. We reexamined localization of xanthine dehydrogenase in the tissue of chicken liver by imrnunohistochemical method, or by the method of isolation of hepatic cells. Chicken liver xanthine dehydrogenase purified by the method of Nishino was used for the immunization of rabbit. The antisera obtained from the rabbit gave a distinct single precipitin line in agar against chicken liver xanthine dehydrogenase or crude extract. This antisera were used for immunohistochemical experiments. Chicken liver were perfused with 4% paraformaldehyde, dehydrated with ethanol, embedded in paraffin and sectioned. They were stained with the indirect method using enzyme labeled antibody. The positive staining was observed in the cytoplasm of hepatocytes, Kupffer cells and endothelial cells, suggesting that these type cells contain xanthine dehydrogenase. After isolation of hepatocytes most of xanthine dehydrogenase was recovered in 100,000xg supernatant fraction from homogenate of hepatocytes and the specific activity of enzyme was similar to that in 100,000xg supernatant fraction from homogenate of liver.