The Effect of Nitrate and Thiocyanate Ions on the Resting and Action Potentials of Cobalt-Treated Single Node of Ranvier

Using the single node of Ranvier, the effect of nitrate and thiocyanate ions with or without cobalt ion was studied.2. The substitution of chloride ions by these less permeable anions resulted in decrease of the critical membrane potential for firing and decrease of the spike height.3. The prolongation of the action potential by cobalt was enhanced in the nitrate or thiocyanate Ringer.4. Chloride depletion is resistant to the inhibition of potassium depolarization by cobalt.5. These results can be explained by the consideration that chloride permeability plays an important role in the node of Ranvier.6. The prolongation of the action potential by cobalt application can be explained speculatively by supposing that the inactivation of sodium carrier system is inhibited by cobalt.7. From the inhibition of potassium depolarization by cobalt, the selective inhibition of potassium permeability was concluded.