ASCORBATE STABILIZATION IS STIMULATED IN RHO-DEGREES-HL-60 CELLS BY COQ(10) INCREASE AT THE PLASMA-MEMBRANE

Long-term treatment with ethidium bromide of HL-60 cells induced a mit ochondria-deficient rho degrees cell line, where mitochondrial DNA can not be identified by PCR and cytochrome c oxidase activity was 80% de creased. These cells showed a progressive increase of ascorbate stabil ization which was 52% higher in the established rho degrees HL-60 cell s. Both CoQ(10) and NADH-ascorbate free radical reductase of the plasm a membrane were increased in rho degrees HL-60 cells compared to paren tal cells, while NADH-cytochrome c reductase was unchanged, CoQ(10) is a component of the ascorbate stabilization activity in the plasma mem brane that would provide both a mechanism to deplete the excess of NAD H produced in rho degrees HL-60 cells and for resistance to oxidative stress. (C) 1997 Academic Press.