The stoicheiometry of sodium ion movement from frog muscle.

1. Further measurements of the consumption of high energy phosphate during the active extrusion of sodium ions from frog muscle were made in the presence of iodoacetate or dinitrofluorobenzene.2. In the presence of iodoacetate the consumption of ATP for phosphorylation of hexose is appreciable and so a deduction is made from the total ATP consumption during the ion movement.3. In the presence of dinitrofluorobenzene the deamination of adenosine monophosphate makes the changes in adenosine triphosphate and diphosphate unequal so that both substances have to be measured.4. The present results point to the active movement of between 2.5 and 3 sodium ions per high energy phosphate bond split.