[9] Isolation of Mitochondria from Morris Hepatomas

There has been considerable interest in the properties of tumor mitochondria during the past 25 years. This interest initially stemmed from Warburg's hypothesis, which predicted respiratory impairment in tumor cells. In recent years, interest in tumor mitochondria has advanced beyond the simple assessment of Warburg's hypothesis. It is now known that mitochondria participate in a variety of metabolic processes other than oxidative phosphorylation, they have the capacity to accumulate ions such as Ca²⁺ and P_i, and that they contain a genetic apparatus that codes for several inner membrane proteins. There have been reports that some types of mitochondria may play a role in virus production. These properties make the mitochondrion an attractive target for studies designed to detect differences between normal and neoplastic tissue. In order to assess such differences, it is necessary to have available reliable mitochondrial isolation procedures. The chapter describes two different procedures for the isolation of mitochondria from Morris hepatomas. Morris hepatomas are particularly suitable as a source of tumor mitochondria because of the considerable stability of each tumor cell line, the availability of cell lines with rapid, slow, and moderate growth rates, and the possibility of using normal and host livers as reasonable controls.