Regular Article :AATEX 3(3):94-105
We determined the in vitro cytotoxicity of 20 MEIC chemicals by flow cytometry. Suspension-cultured Daudi cells were pre-stained with rhodamine-123 and treated with MEIC chemicals for 3 hr. Rhodamine-123 localizing preferentially in mitochondria was detected quantitatively. Relative changes in cell size and intracellular structure were also determined simultaneously by monitoring the relative forward and side scattering fluorescence intensity, respectively, by flow cytometry. Different patterns of these 3 parameters were observed in cells treated with different chemicals. For example, acetylsalicylic acid decreased rhodamine-123 content at the 50% effective dose (ED50) Of 1.07 mM but did not affect the other 2 parameters. However, amitriptyline-HCl decreased all 3 parameters near ED50 Values, while digoxin increased the side scattering light intensity suggesting that a dramatic change may have occurred in the intracellular structure. Based on these patterns, we classified toxicity of the MEIC chemicals into 5 types. ED50 Values for the rhodamine-123 release caused by the test chemicals were highly correlated with those derived from MTT assay, LDH-release assay, and the image analysis assay which we developed previously. This simple flow cytometric assay provides a new sight in cytotoxicity assays of chemicals.