Comparison of cell death and adenosine triphosphate content as indicators of acute toxicity in vitro

1. Anchorage-independent LS cells, derived from L929 mouse fibroblasts, were used as an in vitro alternative to animals for the assessment of acute toxicity. The two end points were cell death, indicated by fluorescein diacetate and ethidium bromide, and intracellular adenosine triphosphate (ATP) content. 2. Concentrations of 20 test compounds which produced a 50% decrease in the ATP contents of control cells (ATP50) ranged from 17 micrograms ml-1 for diethylstilboestrol to 7.0 mg ml-1 for sodium chloride. 3. The concentrations which caused 50% cell death ranged from 16 micrograms ml-1 for diethylstilboestrol to 8.0 mg ml-1 for paracetamol. 4. There was a good numerical correlation (r = 0.99) between the ranks of ATP50 and CD50 end-points, there being only minor changes in order between the ranks. 5. The slopes of the dose-response plots for individual chemicals were markedly different.