Blocking kinetics of the anomalous potassium rectifier of tunicate egg studied by single channel recording
1. The kinetics of the anomalous K current produced by blocking cations Na, Cs and Sr were analysed by single channel recording in the tunicate egg cell. 2. The openâclose kinetics in a single channel with the presence of blocking cation were consistent with the blocking kinetics of the total anom...
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Published in | The Journal of physiology Vol. 331; no. 1; pp. 311 - 331 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
England
The Physiological Society
01.10.1982
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Subjects | |
Online Access | Get full text |
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Summary: | 1. The kinetics of the anomalous K current produced by blocking cations Na, Cs and Sr were analysed by single channel recording
in the tunicate egg cell.
2. The openâclose kinetics in a single channel with the presence of blocking cation were consistent with the blocking kinetics
of the total anomalous K current. The openâclose kinetics in a single anomalous K rectifier channel could be regarded as the
first order transition between the open and closed states.
3. The closing rate constants of the single channel for the first order transition increased almost linearly on a semilogarithmic
scale as the membrane potential became more negative, while the opening rate constants decreased and then increased, showing
the minimum at a certain potential level. The latter indicated that the channel was released from the blocking by excessive
hyperpolarization.
4. The opening rate constant increased in spite of the fixed concentration of the blocking cation (10 μM-Cs), when the external
K concentration was raised from 200 mM to 400 mM. This result suggested that there are interactions within the channel between
the blocking cation and the K ion.
5. When there were two kinds of blocking cations such as Na and Cs, the kinetic properties in a single channel indicated that
the two kinds of blocking cations blocked the single channel independently.
6. The single channel conductance of the anomalous K rectifier in 200 mM-Na-containing 200 mM-K solutions was about 1·5 times
larger than that in Na-free 200 mM-K solutions.
7. The single channel conductances in 100, 200 and 400 mM-K solution with 10 μM-Cs were 5·0, 7·1 and 12·3 pS respectively,
being roughly proportional to the square root of the K concentration.
8. The density of the anomalous K rectifier channel in the tunicate egg cell was 0·039/μm 2 .
9. The amplitude of the single channel current increased with the rise of temperature, the Q 10 being 1·5. |
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Bibliography: | Present address: Jerry Lewis Neuromuscular Research Center, School of Medicine, University of California, Los Angeles, CA 90024, U.S.A. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.1982.sp014374 |