RESTING AND ACTION POTENTIAL OF SQUID GIANT AXONS INTRACELLULARLY PERFUSED WITH SODIUM-RICH SOLUTIONS

Abstract

Excised giant axons of the squid were perfused intracellularly with Na-glutamate solutions, with or without adding K-glutamate. Immersing the axons in media containing the same Na-concentration as the perfusing fluid, all-or-none action potentials with a large overshoot were observed for more than one hour. Replacement of Na-ion in the perfusing fluid with K-ion did not bring about any significant change in the resting potential. This finding is consistent with the view that the K- and Na-permeabilities are not very different in the resting, excitable state of the membrane. At high concentrations of Na-ion in the perfusing fluid, the difference in chemical species of anions in the perfusing fluid changed significantly the electrophysiological behavior of the axon.