Potassium permeability in myelinated nerve fibres of Xenopus laevis

In the two preceding papers (Frankenhaeuser, 1962a, b) it was shown that the delayed current in the myelinated nerve fibre is carried essentially by potassium ions, and that potassium moves passively in its electrochemical gradient. The aim of the present investigation is to find an empirical expression that describes the potassium transport mechanism. It will be shown that the simple constant-field equation (Goldman 1943; Hodgkin & Katz, 1949; Dodge & Frankenhaeuser, 1959) is applicable to the experimental data, even though some limitations to the treatment were observed.