Abstract
The low concentrations of vitamin B_<12> increased the skin potential by inner surface application of the skin and caused hyperpolarization in nerve and the augmented action potential, while high concentrations of vitamin B_<12> decreased the skin potential and caused depolarization in nerve and the reduced action potential. The outer surface application of low and high concentrations of vitamin B_<12> induced the decrease of skin potential and hyperpolarization in nerve disappeared in NO_3-Ringer. Among these effects of vitamin B_<12>, the increase of skin potential by inner surface application, hyperpolarization in nerve and the decrease of skin potential by outer surface application were abolished by CuSO_4 containing Ringer which depressed chloride permeability. The decrease of skin potential by inner surface application and depolarization in nerve caused by high concentration of vitamin B_<12> disappeared in the K-free Ringer which depressed the Na-K active transport. From these results it was estimated that vitamin B_<12> has two different actions on skin and nerve membrane, one is the enhancement of chloride permeability and the other is the effect on the Na-K active transport.
