Inhibition of succinate-linking reduction of pyridine nucleotide in rat liver mitochondria 'in vivo' by N-(phosphonomethyl)glycine.

The pattern of the interaction of N-(phosphonomethyl)glycine (PMG), a broad-spectrum and non-selective herbicide with succinate-linked reduction of pyridine nucleotide, was investigated in liver mitochondria isolated 5 h after albino rats were given i.p. injections of PMG. Although there was no appreciable inhibition of the reduction of pyridine nucleotide at dosage levels less than 150 mg PMG/kg, the extent of inhibition increased as the dose was raised to 240 mg PMG/kg. Maximal inhibition of 34.5% and 45.4% were obtained at 240 mg PMG/kg when externally added ATP and high-energy intermediate, respectively, were used as the source of energy. These findings suggest that the inhibitory effect of PMG may be due to its uncoupling effect on oxidative phosphorylation.