Interaction of internal anions with potassium channels of the squid giant axon

D. J. Adams, G. S. Oxford

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The interaction of internal anions with delayed rectifier potassium channel was studied in perfused squid axons. Changing the internal potassium salt from K+ glutamate- to KF produced a reversible decline of outward K currents and a marked slowing of the activation of K channels at all voltages. Fluoride ions exert a differential effect upon K channel gating kinetics whereby activation of I(K) during depolarizing steps is slowed dramatically, but the rate of closing after the step is not much altered. These effects develop with a slow time course (30-60 min) and are specific for K channels over Na channels. Both the amplitude and activation rate of I(K) were restored within seconds upon return to internal glutamate solutions. The fluoride effect is independent of the external K+ concentration and test membrane potential, and does not recover with repetitive application of depolarizing voltage steps. Of 11 different anions tested, all inorganic species induced similar decreases and slowing of I(K), while K currents were maintained during extended perfusion with several organic anions. Anions do not alter the reversal potential or shape of the instantaneous current-voltage relation of open K channels. The effect of prolonged exposure to internal fluoride could be partially reversed by the addition of cationic K channel blocking agents such as TEA+, 4-AP+, and Cs+. The competitive antagonism between inorganic anions and internal cationic K channel blockers suggests that they may interact at a related site(s). These results indicate that inorganic anions modify part of the K channel gating mechanism (activation) at a locus near the inner channel surface.

Original languageEnglish (US)
Pages (from-to)429-448
Number of pages20
JournalJournal of General Physiology
Volume82
Issue number4
StatePublished - 1983
Externally publishedYes

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Decapodiformes
Potassium Channels
Anions
Axons
Fluorides
Glutamic Acid
Delayed Rectifier Potassium Channels
Membrane Potentials
Potassium
Perfusion
Salts
Ions

ASJC Scopus subject areas

  • Physiology

Cite this

Interaction of internal anions with potassium channels of the squid giant axon. / Adams, D. J.; Oxford, G. S.

In: Journal of General Physiology, Vol. 82, No. 4, 1983, p. 429-448.

Research output: Contribution to journalArticle

Adams, D. J. ; Oxford, G. S. / Interaction of internal anions with potassium channels of the squid giant axon. In: Journal of General Physiology. 1983 ; Vol. 82, No. 4. pp. 429-448.
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