Abstract
The effects of osmotic pressure on the nerve excitation in the squid giant axon were described. The osmotic pressure affected the nerve excitation in two different ways : (1) in the absence of its difference across the membrane, an increase in osmorality and an increased microscopic viscosity of solutions slowed down the kinetics of nerve excitation, and (2) in the presence of its difference, a net water flow occurred across the membrane, and this water movement affected ionic channels in a direct and an indirect manner. The latter effects on K-channel revealed qualitative differences from those on Na-channel. Further anylysis of these osmolarity effects on ionic channels may prove valuable in clarifying the molecular mechanism of nerve excitation.
