Analyses of populations of NIH/3T3 cells for mitochondrial DNA under various conditions were made by use of an improved procedure. Cells were examined at different cell densities, at different stages of cell growth, and after the cells had been incubated with a carcinogen reported to affect mitochondrial DNA replication, benzo[a]pyrene-epoxide. In addition, the analysis was performed on three tumorigenic NIH/3T3 cell lines and one mouse bladder epithelial cell line and its tumorigenic derivative. Small variations of mitochondrial DNA under these various conditions were detected easily and revealed a linear relationship between mitochondrial DNA and total cell DNA.
