The inhibition of phosphate entry into rat liver mitochondria by organic mercurials and by formaldehyde.

The energy conserved during oxidoreduction in the mitochondrial respiratory chain may be used either for ATP synthesis or in other energy-linked reactions, including the uptake of univalent and bivalent cations (Ernster & Lee, 1964). A sustained phase of cation uptake by isolated mitochondria, and a concurrent increase in the respiration rate, usually requires the addition of a permeant anion, e.g. phosphate or acetate. Univalent cation uptake is stimulated strongly by the antibiotics valinomycin and gramicidin (Moore & Pressman, 1964; Pressman, 1965; Chappell & Crofts, 1965). A reaction mechanism for Ca2+ uptake by mitochondria (Chance, 1965), in terms of the chemical coupling hypothesis of respiratory-chain phosphorylation (Slater, 1953), postulates that the cation reacts with a high-energy intermediate