Evaluation of mitochondrial content and activity with nonyl-acridine orange and rhodamine 123: flow cytometric analysis and comparison with quantitative morphometry. Comparative analysis by flow cytometry and quantitative morphometry of mitochondrial content and activity.

Mouse fibroblasts 3T3.4E and two cells lines obtained by fusion (3T3.4E cells x normal human keratinocytes), (3T3 x NHK), and (3T3.4E cells x hand wart keratinocytes), (3T3 x HWK), were compared for mitochondrial activity and content between 5 and 20 days of culture, from the 16th to 20th passage, by using Rh 123 and NAO respectively. In 3T3.4E cells both Rh 123 and NAO fluorescence were similar after 5 and 7 days of culture, indicating no modification of mitochondrial activity and content at that time. However, in cells derived from fusion of 3T3 x NHK or 3T3 x HWK, Rh 123 increased from 5 to 20 days whereas NAO fluorescence was maximal at 7 days of culture and then decreased, indicating that their mitochondrial activity differed from that of 3T3.4E cells. No difference was observed between the 16th and 20th passage. Quantitative morphometry and flow cytometry gave good correlations at 7 days of culture for the cell size, estimated either by the cell area or the cell diameter, and for mitochondria content, evaluated either by the number of mitochondria per cell or NAO fluorescence intensity.