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Biophys J. 1978 Nov;24(2):569-74.

Sodium inactivation mechanism modulates QX-314 block of sodium channels in squid axons.

Abstract

Blocking action of Na channels by QX-314, a quaternary derivative of lidocaine, was studied in internally perfused and voltage-clamped axons of squid. In axons with intact Na inactivation, QX-314 exhibited both a frequency- and a voltage-dependent block of Na channels. Repetitive pulsing to more positive potentials enhanced the degree of block. Both frequency- and voltage-dependent blocks disappeared in axons in which Na inactivation had been destroyed by either pronase or N-bromoacetamide treatment. These results support the notion that Na inactivation not only modulates the frequency-dependent block but also involves the voltage-dependent binding reaction between QX-314 and Na channels.

PMID:
728531
PMCID:
PMC1473424
DOI:
10.1016/S0006-3495(78)85403-4
[Indexed for MEDLINE]
Free PMC Article

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