Stimulation of Cellular XTT Reduction by Cytochrome Oxidase Inhibitors

Abstract

XTT reducing activity by CHO and L1210 cells was found to be stimulated by the presence of cytochrome oxidase inhibitors such as NaN₃ or KCN. Among the other respiratory chain inhibitors, antimycin A (a complex III inhibitor) and chlorpromazine inhibited cellular XTT reduction, and rotenone and malonate showed sligth inhibition and no effect, respectively. It is suggested that XTT reduction is coupled with the respiratory chain via cytochrome c, which is located between complexes III and IV (cytochrome oxidase).