Effect of lonidamine and rhein on the phosphorylation potential generated by respiring rat liver mitochondria.

The effect of lonidamine (LND) and rhein (RH) on the extramitochondrial phosphorylation potential [delta Gp (out)] generated by respiring rat liver mitochondria using succinate and glutamate as substrates has been investigated. LND decreases in a similar quantitative manner the delta Gp (out) of mitochondria respiring either on succinate or glutamate, whereas RH is more effective when glutamate is the substrate. The decrease brought about by the two drugs may be mainly ascribed to an inhibition of the rate of electron transport through the respiratory carriers, thus lowering the phosphorylation rate. The possible implications of a reduced ATP availability in tumor cells are discussed.