Effect of Silver Ions on Mitochondrial Adenosine Triphosphatase

Abstract

Abood, Gerard and Ochs¹ claim that the respiration of cell-free dispersions and mitochondria of brain tissue was increased by the passage of electrical impulses between silver electrodes in the suspension medium. In general, increase in the respiratory rate of well-prepared mitochondria is consequent upon increase in the rate of removal of adenosine triphosphate, by addition of systems which catalyse its dephosphorylation, or through activation of the mitochondrial adenosine triphosphatase². We were thus led to test the effect of electrical impulses on the adenosine triphosphatase activity of mitochondria, obtained from rabbit cerebral cortex, using the medium which had enabled the preparation of mitochondria of low initial adenosine triphosphatase activity from pigeon breast muscle³. For the adenosine triphosphatase assays the particles were incubated for 10 min. at 20° in a medium of the following approximate composition: 0.1 M potassium chloride, 0.05 M aminotrishydroxymethylmethane-hydrochloride buffer pH 7.4, 0.005M magnesium sulphate, 0.005–0.0075 M sodium adenosine triphosphate, and 5 × 10⁻⁵ M ethylenediaminetetraacetate. With 0.0075 M adenosine triphosphate, mitochondria from 60 mgm. of tissue liberated about 20 µgm. of inorganic phosphate under these conditions, and the activity was increased three-fold on addition of 10⁻⁴ M 2 : 4-dinitrophenol.