Abstract
1. Sodium and potassium currents have been recorded in intracellularly perfused squid giant axons before, during and after exposure to solutions of n-pentane in artificial sea water. 2. The currents were fitted with equations similar to those proposed by Hodgkin & Huxley (1952) and the changes in the parameters of these equations in the presence of pentane were calculated. 3. In the range of membrane potential -40 to 40 mV, the time constants for activation (tau m) and inactivation (tau h) of the Na current, and for activation (tau n) of the K current were all reduced by the pentane. 4. The curve of the steady-state inactivation parameter (h infinity) for the Na current against membrane potential was shifted by the pentane in a hyperpolarizing direction (at h infinity = 0.5 this shift was approx. -15 mV in 275 microM-pentane) and the slope at all potentials was reduced. 5. The curve of the steady-state activation parameter (m infinity) for the Na current against membrane potential was also shifted by the pentane in a hyperpolarizing direction (in 153 microM-pentane, 10 mV at m infinity = 0.5). 6. The maximum Na and K conductances gNa and gK were lowered by the pentane, though not usually completely reversibly. 7. The changes in position and slope of the steady-state inactivation curve have been tentatively accounted for in terms of an increase in membrane thickness.
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Selected References
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