Abstract
The effects of gallamine on ionic currents in single intact Ranvier nodes of the toad Xenopus were investigated. The following fully reversible effects were observed: 1. With a test concentration of 1 mmol/1 the current-voltage relation of steady-state potassium currents, IKss exhibited a complete block of IKss up to about V = 110 mV; with stronger depolarisations the block was incomplete. The peak sodium currents, in contrast, were not affected. 2. At the same test concentration the potassium permeability constant P̄K was reduced by 92 % from its normal value, while the sodium permeability constant P̄Na decreased by only 8%. 3. Concentration-response relations of the block of P̄K yielded an apparent dissociation constant of 30 μmol/1 and a steepness parameter of unity. Patch-clamp experiments on cloned Kv1.1, Kv1.2, Kv1.3 and Kv3.1 channels yielded apparent dissociation constants of 86, 19, ≫100 and 121 μmol/1, respectively. Our findings show that gallamine is particularly well suited for separating potassium and sodium currents in axonal current ensembles. They also strongly suggest that potassium currents in Ranvier nodes of Xenopus are mainly carried by an ensemble of Kv1.1 and 1.2 channels.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 83-95 |
| Number of pages | 13 |
| Journal | General Physiology and Biophysics |
| Volume | 20 |
| Issue number | 1 |
| State | Published - Mar 2001 |
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Keywords
- Gallamine triethiodide
- Kv-channel blocker
- Node of Ranvier
ASJC Scopus subject areas
- Physiology
- Biophysics
Cite this
Gallamine triethiodide selectively blocks voltage-gated potassium channels in Ranvier nodes. / Hinck, D.; Wulff, Heike; Koppenhöfer, Eilhard.
In: General Physiology and Biophysics, Vol. 20, No. 1, 03.2001, p. 83-95.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Gallamine triethiodide selectively blocks voltage-gated potassium channels in Ranvier nodes
AU - Hinck, D.
AU - Wulff, Heike
AU - Koppenhöfer, Eilhard
PY - 2001/3
Y1 - 2001/3
N2 - The effects of gallamine on ionic currents in single intact Ranvier nodes of the toad Xenopus were investigated. The following fully reversible effects were observed: 1. With a test concentration of 1 mmol/1 the current-voltage relation of steady-state potassium currents, IKss exhibited a complete block of IKss up to about V = 110 mV; with stronger depolarisations the block was incomplete. The peak sodium currents, in contrast, were not affected. 2. At the same test concentration the potassium permeability constant P̄K was reduced by 92 % from its normal value, while the sodium permeability constant P̄Na decreased by only 8%. 3. Concentration-response relations of the block of P̄K yielded an apparent dissociation constant of 30 μmol/1 and a steepness parameter of unity. Patch-clamp experiments on cloned Kv1.1, Kv1.2, Kv1.3 and Kv3.1 channels yielded apparent dissociation constants of 86, 19, ≫100 and 121 μmol/1, respectively. Our findings show that gallamine is particularly well suited for separating potassium and sodium currents in axonal current ensembles. They also strongly suggest that potassium currents in Ranvier nodes of Xenopus are mainly carried by an ensemble of Kv1.1 and 1.2 channels.
AB - The effects of gallamine on ionic currents in single intact Ranvier nodes of the toad Xenopus were investigated. The following fully reversible effects were observed: 1. With a test concentration of 1 mmol/1 the current-voltage relation of steady-state potassium currents, IKss exhibited a complete block of IKss up to about V = 110 mV; with stronger depolarisations the block was incomplete. The peak sodium currents, in contrast, were not affected. 2. At the same test concentration the potassium permeability constant P̄K was reduced by 92 % from its normal value, while the sodium permeability constant P̄Na decreased by only 8%. 3. Concentration-response relations of the block of P̄K yielded an apparent dissociation constant of 30 μmol/1 and a steepness parameter of unity. Patch-clamp experiments on cloned Kv1.1, Kv1.2, Kv1.3 and Kv3.1 channels yielded apparent dissociation constants of 86, 19, ≫100 and 121 μmol/1, respectively. Our findings show that gallamine is particularly well suited for separating potassium and sodium currents in axonal current ensembles. They also strongly suggest that potassium currents in Ranvier nodes of Xenopus are mainly carried by an ensemble of Kv1.1 and 1.2 channels.
KW - Gallamine triethiodide
KW - Kv-channel blocker
KW - Node of Ranvier
UR - http://www.scopus.com/inward/record.url?scp=0034962134&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034962134&partnerID=8YFLogxK
M3 - Article
C2 - 11508824
AN - SCOPUS:0034962134
VL - 20
SP - 83
EP - 95
JO - General Physiology and Biophysics
JF - General Physiology and Biophysics
SN - 0231-5882
IS - 1
ER -