Adenosine triphosphate as an indicator of cellular toxicity In vitro

Using a mouse fibroblast line (L929-derived LS) in suspension culture and adenosine triphosphate (ATP) levels as the endpoint, a highly predictive screen for toxicity has been developed and subjected to validation. Cells were exposed to chemicals of known toxicity for 4 hr and levels of ATP were determined using the luciferin/luciferase bioluminescent system, emitted light being measured in an automated Packard luminometer. Concentrations producing a 50% reduction in cellular ATP (ATP 50) were compared with those causing 50% cell death (CD 50) as established with the fluorescent dyes, fluorescein diacetate and ethidium bromide. Ranking of the chemicals according to the ATP 50 was generally similar to that based on the CD 50 determinations and demonstrated a range of toxicity from very mild to severe.