Na+ channels from rat muscle plasma membrane vesicles were inserted into neutral planar phospholipid bilayers and were activated by batrachotoxin. Single channel blocking events induced by the addition of various guanidinium toxins were analyzed to derive the rates of channel-toxin association and dissociation. Blocking by tetrodotoxin, saxitoxin, and six natural saxitoxin derivatives containing sulfate or hydroxyl groups were studied. Although the binding affinities vary over 2,000-fold, all of the toxins exhibit identical voltage dependence of the blocking reactions, regardless of the toxin's net charge. The results suggest that the voltage dependence of toxin binding is due to a voltage-dependent conformational equilibrium of the toxin receptor, rather than to direct entry of the charged toxin molecule into the applied transmembrane electric field.
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1 November 1984
Article|
November 01 1984
Voltage-dependent blockade of muscle Na+ channels by guanidinium toxins.
E Moczydlowski
S Hall
S S Garber
G S Strichartz
C Miller
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1984) 84 (5): 687–704.
Citation
E Moczydlowski, S Hall, S S Garber, G S Strichartz, C Miller; Voltage-dependent blockade of muscle Na+ channels by guanidinium toxins.. J Gen Physiol 1 November 1984; 84 (5): 687–704. doi: https://doi.org/10.1085/jgp.84.5.687
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