IN VITRO CYTOTOXICITY OF 20 MEIC CHMICALS WITH "QUANTUM-TYPE" RELEASE OF RHODAMINE 123 DETECTED BY FLOW CYTOMETRY

XINHAI WANG1,2, SHU QIN LIU1, SONGHUA CHEN1,3, XI RUI GE3, KAORU SAIJOl and TADAO OHNO1
1RIKEN Cell Bank, The Institute of Physical and Chemical Research (RIKEN), 3-1-1, Koyadai, Tsukuba Science City, Ibaraki 305, Japan
2Institute of Laboratory Animals, Beijing agricultural University, 2 West Yuanmingyuan Road, Beijin 100094, China
3Shanghai Institute of Cell Biology, Chinese Academy of Science, 320 Yue Yang Road, Shanghai, China


Regular Article :AATEX 3(3):94-105

Abstract
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.


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