The effects of n-pentane on voltage-clamped squid nerve sodium currents. A reinterpretation using kinetics of ordered systems.

The sodium-current voltage-clamp data of Haydon and Kimura obtained on squid nerves treated with n-pentane (J. Physiol. 312 (1981) 57) are fitted with a previously described model (K.A. Rubinson, J. Physiol. 281 (1978) 14P; Biophys. Chem. 15 (1982) 245). The apparently complex action of the perturbant can be interpreted as due to a shift in shielding of the applied potential jumps, a change in channel conductivity, and an increase in the rate constant of channel shutoff. The shift in shielding due to n-pentane is found to be quantitatively the same for variables describing both kinetic and equilibrium quantities, which are independent. The transmembrane sodium potential remains unchanged, however.