Differences in Distribution Pattern of Marker Enzymes among Subcellular Fractions from Morris Hepatoma 161

The distribution of marker enzymes in subcellular frac tions isolated by differential centrifugation was determined in Morris hepatoma 16, host liver, and control rat liver. Marker enzymes of cellular organdÃ-esthat were assayed in cluded cytochrome oxidase, monoamine oxidase, ornithine aminotransferase, D-amino acid oxidase, acid phosphatase, glucose 6-phosphatase, ethylmorphine demethylase, and lactic dehydrogenase. Comparison of host liver and hepa toma revealed significant differences in the distribution pattern of many of these enzymes, especially those asso ciated with mitochondria. The hepatoma showed increased amounts of mitochondria! enzyme activity in a subcellular fraction requiring higher g forces than normal for sedimen tation. This could mean that hepatoma 16contains a greater proportion of mitochondria that are smaller in size and/or less dense than those of host or normal liver. Electron micro graphs of hepatoma and host liver tissue and subcellular fractions also suggested that hepatoma 16 contains mito chondria that are smaller in size. It is concluded, therefore, that a greater proportion of mitochondria of hepatoma 16 are smaller in size than those of host liver.