The Mitochondrial ToxGlo™ Assay is a cell-based assay method that employs a sequential addition, multiplexed assay chemistry for predicting potential mitochondrial dysfunction as a result of xenobiotic exposure. The assay is based on the differential measurement of biomarkers associated with changes in cell membrane integrity and cellular ATP levels relative to vehicle-treated control cells during short exposure periods. Cell membrane integrity is first assessed by measuring the presence or absence of a distinct protease activity associated with necrosis using a fluorogenic peptide substrate (bis-AAF-R110) to measure "dead cell protease activity". The bis-AAF-R110 substrate cannot cross the intact membrane of live cells and therefore gives no signal with viable cells. Next, ATP is measured by adding an ATP detection reagent, resulting in cell lysis and generation of a luminescent signal proportional to the amount of ATP present. The two sets of data can be combined to produce profiles representative of mitochondrial dysfunction or non-mitochondrial related cytotoxic mechanisms.
Mammalian cells generate ATP by mitochondrial (oxidative phosphorylation) and non-mitochondrial (glycolysis) methods. To achieve optimal mitochondrial responsiveness, it may be necessary to refine cell culture conditions. Replacing glucose-supplemented medium with galactose-containing medium may increase cellular oxygen consumption and augment mitochondrial susceptibility to mitotoxicants.