Activity and Ultrastructure of Mitochondria from Mouse Mammary Gland and Mammary Adenocarcinoma 1

Mitochondria isolated from normal mammary glands taken from lactating and nonlactating C3H mice were compared with those isolated from mammary adenocarcinomas. Functional mitochondria could be obtained from the normal mammary glands only when milk was not present in the tissue prior to homogenization and when bovine serum albumin was added to the isolation medium. Albumin also protected tumor mitochondria from destructive factors released into the homogenate by disruption of the tumor cells. Although normal mammary glands contained more mitochondria per of g of tissue than did the mammary adenocarcinomas, no major differences were observed in ultrastructure, phosphorylation, rate of substrate oxidation, phosphate ion transport, passive swelling, or cytochrome content between functional mitochondria from normal and neoplastic tissues. These studies suggest that there is no impairment in the functioning of mitochondria in the mammary adenocarcinoma.