Some factors influencing the plateau-formation in Co-treated or Nitreated single myelinated nerve fibres.

In the previous papers,TAKAHASHI et al.1,2)reported the effects of divalent transition metals,such as Co and Ni on the excitation mechanism of the myelinated nerve fibre.According to their observations,the main features of the effects of these metals are(a)increase in the rheobase,(b)enormous prolongation of the action current or potential forming a 'plateau' and (c) formation of a marked 'shoulder' in the action potential from which the membrane potential falls rapidly toward the resting level.The remarkable plateau-forming action of nickel ion upon the action potential of the myelinated nerve fibre was also observed by BRADY et al.3) The main purpose of the present investigation was to examine the effects of some agents on the plateau formation of the action current in Co-treated or Ni-treated myelinated nerve fibres,in order to elucidate some characteristics of the excitation mechanism of the nodal membrane.