[The effect of changes in the pH of the external solution on the afterpotentials of individual frog nodes of Ranvier].

A decrease in pH to 5 elicited a small increase in afterdepolarization of a single Ranvier node and an increase in pH to 9 had no effect. Post-tetanic hyperpolarization decreases at pH 5 and its duration somewhat increases. An increase in pH to 9 also had no effect. Similar changes in afterdepolarization and post-tetanic hyperpolarization were observed in potassium free solutions. A conclusion is made that changes in afterpotentials are determined by changes in kinetics of the membrane potassium permeability.