Ubiquinone and vitamin K in bacteria.

3. Liver mitochondria isolated after suspension in 5 mM-sodium salicylate in 0-44m-sucrose carried out oxidative phosphorylation nearly as efficiently as the controls. 4. Salicylate was taken up by mitochondria at 00, but the binding was extremely labile. From 78 to 95 % of the salicylate taken up was removed by one rapid wash in sucrose medium. 5. The intracellular fluid of the livers of sailcylate-poisoned rats contained concentrations of salicylate from 0-8 to 4 0 mm. These concentrations approximate to the concentrations of salicylate in the plasma of these animals. 6. The presence of salicylate in the intracellular fluid of the livers of rats poisoned with salicylate in vivo is compatible with a physiological uncoupling effect of salicylate on mitochondria in vivo. Uncoupling cannot be demonstrated in mitochondria isolated from intoxicated rats because the salicylate is washed out during the isolation procedure.