Author Correction: Bases of Bacterial Sodium Channel Selectivity Among Organic Cations

The relative permeability of sodium channels to 21 organic cations was studied in myelinated nerve fibers. Ionic currents under voltage-clamp conditions were measured in sodium-free solutions containing the test cation. The measured reversal potential and the Goldman equation were used to calculate relative permeabilities. The permeability sequence was: sodium ≈ hydroxylamine > hydrazine > ammonium ≈ formamidine ≈ guanidine ≈ hydroxyguanidine > aminoguanididine >> methylamine. The cations of the following compounds were not measurably permeant: N-methylhydroxylamine, methylhydrazine, methylamine, methylguanidine, acetamidine, dimethylamine, tetramethylammonium, tetraethylammonium, ethanolamine, choline, tris(hydroxymethyl)amino methane, imidazole, biguanide, and triaminoguanidine. Thus methyl and methylene groups render cations impermeant. The results can be explained on geometrical grounds by assuming that the sodium channel is an oxygen-lined pore about 3 A by 5 A in cross-section. One pair of oxygens is assumed to be an ionized carboxylic acid. Methyl and amino groups are wider than the 3 A width of the channel. Nevertheless, cations containing amino groups can slide through the channel by making hydrogen bonds to the oxygens. However, methyl groups, being unable to form hydrogen bonds, are too wide to pass through.

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Modified kinetics and selectivity of sodium channels in frog skeletal muscle fibers treated with aconitine.

The Journal of General Physiology ◽

10.1085/jgp.80.5.713 ◽

1982 ◽

Vol 80 (5) ◽

pp. 713-731 ◽

Cited By ~ 20

Author(s):

D T Campbell

Keyword(s):

Skeletal Muscle ◽

Sodium Channel ◽

Sodium Channels ◽

State Level ◽

Steady State Level ◽

Channel Block ◽

Frog Skeletal Muscle ◽

Channel Kinetics ◽

Ionic Selectivity ◽

Channel Selectivity

The effect of the plant alkaloid aconitine on sodium channel kinetics, ionic selectivity, and blockage by protons and tetrodotoxin (TTX) has been studied in frog skeletal muscle. Treatment with 0.25 or 0.3 mM aconitine alters sodium channels so that the threshold of activation is shifted 40-50 mV in the hyperpolarized direction. In contrast to previous results in frog nerve, inactivation is complete for depolarizations beyond about -60 mV. After aconitine treatment, the steady state level of inactivation is shifted approximately 20 mV in the hyperpolarizing direction. Concomitant with changes in channel kinetics, the relative permeability of the sodium channel to NH4,K, and Cs is increased. This altered selectivity is not accompanied by altered block by protons or TTX. The results suggest that sites other than those involved in channel block by protons and TTX are important in determining sodium channel selectivity.

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Sodium channel selectivity filter regulates antiarrhythmic drug binding

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.94.25.14126 ◽

1997 ◽

Vol 94 (25) ◽

pp. 14126-14131 ◽

Cited By ~ 81

Author(s):

A. Sunami ◽

S. C. Dudley ◽

H. A. Fozzard

Keyword(s):

Sodium Channel ◽

Antiarrhythmic Drug ◽

Drug Binding ◽

Selectivity Filter ◽

Channel Selectivity

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Importance of position 8 in μ-conotoxin KIIIA for voltage-gated sodium channel selectivity

FEBS Journal ◽

10.1111/j.1742-4658.2011.08264.x ◽

2011 ◽

Vol 278 (18) ◽

pp. 3408-3418 ◽

Cited By ~ 28

Author(s):

Annelies Van Der Haegen ◽

Steve Peigneur ◽

Jan Tytgat

Keyword(s):

Sodium Channel ◽

Voltage Gated Sodium Channel ◽

Voltage Gated ◽

Channel Selectivity

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Sodium channel selectivity. Dependence on internal permeant ion concentration.

The Journal of General Physiology ◽

10.1085/jgp.68.2.111 ◽

1976 ◽

Vol 68 (2) ◽

pp. 111-125 ◽

Cited By ~ 36

Author(s):

M Cahalan ◽

T Begenisich

Keyword(s):

Sodium Channel ◽

Ion Concentration ◽

Selectivity Ratio ◽

Squid Axon ◽

Perfusion Medium ◽

Chloride Permeability ◽

Channel Selectivity ◽

Sucrose Solutions ◽

Internal Concentration ◽

Reversal Potentials

The selectivity of sodium channels in squid axon membranes was investigated with widely varying concentrations of internal ions. The selectivity ratio, PNa/PK, determined from reversal potentials decreases from 12.8 to 5.7 to 3.5 as the concentration of internal potassium is reduced from 530 to 180 to 50 mM, respectively. The internal KF perfusion medium can be diluted by tetramethylammonium (TMA), Tris, or sucrose solutions with the same decrease in PNa/PK. The changes in the selectivity ratio depend upon internal permeant ion concentration rather than ionic strength, membrane potential, or chloride permeability. Lowering the internal concentration of cesium, rubidium, guanidnium, or ammonium also reduces PNa/Pion. The selective sequence of the sodium channel is: Na greater than guanidinium greater than ammonium greater than K greater than Rb greater than Cs.

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