Phosphate Incorporation in Desheathed Nerves: Effects of Potassium and Calcium Ions

In the presence of Ringer's solution containing a high concentration of potassium ions, the incorporation of P 32 -orthophosphate into adenosine triphosphate and other organophosphates of the desheathed sciatic nerve of the bullfrog was inhibited by more than 75 percent. In calcium-free Ringer's solution containing ethylenediaminetetraacetic acid, the inhibition was about 30 percent. Both solutions depolarized the nerves, and the depolarization probably interfered with the mechanisms of phosphate transfer rather than directly with phosphorylation. The inhibition may have been a consequence of the decreased adsorption of phosphates which occurs at the excitable surface during depolarization.