Some ultrastructural and biochemical characteristics of tumor mitochondria isolated in albumin-containing media.

Mitochondria from a variety of mouse and rat tumors were studied. In general, tumor mitochondria isolated in a medium containing bovine serum albumin (BSA) exhibit respiratory control, while mitochondria isolated from the same tumor in the absence of BSA lack respiratory control. Some variability in oxidative phosphorylation was obtained among the various types of tumors. The rates of phosphorylating oxygen con sumption of the tumor mitochondria isolated in BSA-containing media were always lower than those of mitochondria obtained from a variety of normal tissues. Electron micro scopic studies of tumor mitochondria isolated with or without BSA revealed a heterogeneity of ultrastructural forms. In contrast to liver mitochondria, tumor mitochondria, although capable of oxidative phosphorylation, did not undergo in vitro transitions in morphology concomitant with changes in bio chemical state. The possible role of albumin in preserving mitochondrial structure and function is discussed.