Effect of the nonionic detergent Triton X‐100 on sodium permeability of the myelinated nerve fibre ofXenopus laevis

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Abstract
The effect of the nonionic detergent Triton X‐100 (TX‐100) on the Na permeability (PNa) properties of the nodal membrane in myelinated nerve fibres ofXenopus laeviswas analysed with potential clamp technique. Application of TX‐100 caused a rapid initial decrease in PNathat was reversible at wash out as well as a slow irreversible block. Both effects depended on [TX‐100] and duration of exposure. The reversible reduction of PNaat the steady state was 50% at 40–60µM TX‐100. The slope of the Hill plot for the reaction was 1.75 indicating a deviation from a first order reaction. The equilibrium dissociation constant (KD) for n = 1.75 was 0.9 × 10‐7(M1.75). KDcalculated from the rate constants for onset and offset of the reversible reaction (KD= k2/k1) was 1.5 × 10‐7(M1.75). The possibility that the action of TX‐100 involves membrane proteins is discussed.