Pfluegers Archiv/European Journal of Physiology 1985-05-01

Effects of chemical modification of amino groups by two different imidoesters on voltage-clamped nerve fibres of the frog.

M Rack

文献索引：Pflugers Arch. 404(2) , 126-30, (1985)

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摘要

Voltage clamped single nerve fibres of the frog Rana esculenta were treated with the amino groups specific reagents ethyl acetimidate and isethionyl acetimidate. Ethyl acetimidate is lipid soluble, relatively non-polar and can penetrate a membrane. Isethionyl acetimidate is lipid-insoluble, polar and membrane-impermeant. Treatment with ethyl acetimidate caused an irreversible reduction of Na currents and a shift of the voltage dependence of the steady-state sodium inactivation, h infinity (E), in the hyperpolarizing direction. The voltage dependence of sodium activation was much less affected and a small shift into the depolarizing direction was observed. By contrast, the non-permeant reagent did not reduce the sodium currents and the shifts of the h infinity (E) curve were smaller than the shifts caused by ethyl acetimidate. Furthermore, a small shift of the voltage-dependence of activation in the hyperpolarizing direction was observed. As the modification procedure with imidoesters does not cause a change of net charge, the results cannot be explained by an effect of surface charge modification; rather, they seem to be due to a direct effect of amino group modification on the voltage dependence of inactivation.