Temperature dependence of human muscle ClC-1 chloride channel
In the present work we investigated the dependence on temperature of the ionic conductance and gating of human muscle ClC-1 chloride channels, transiently expressed in human embryonic kidney (HEK 293) cells. At normal pH, ClC-1 currents deactivated at negative potentials with a double-exponential ti...
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Published in | The Journal of physiology Vol. 535; no. 1; pp. 83 - 93 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
15.08.2001
Blackwell Science Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | In the present work we investigated the dependence on temperature of the ionic conductance and gating of human muscle ClC-1
chloride channels, transiently expressed in human embryonic kidney (HEK 293) cells.
At normal pH, ClC-1 currents deactivated at negative potentials with a double-exponential time course. The time constants
of the exponential components, corresponding to the relaxations of the fast and slow gates, were temperature dependent with
Q 10 values of â3 and â4, respectively. Current amplitude increased with increasing temperature with a Q 10 of â1.6.
The voltage dependence of the two gating processes was shifted towards more positive potentials with increasing temperature.
The half-saturation voltage ( V 1/2 ) of the steady-state open probability ( P o ) was shifted by â23 and â34 mV per 10 °C increase in temperature, for the fast and slow gate, respectively.
At low pH, the voltage dependence of ClC-1 was reversed and currents were activated by hyperpolarisation with a single-exponential
time course. This type of gating in ClC-1 resembled the slow gating of the Torpedo ClC-0 homologue, but differed with respect to its kinetics and temperature dependence, with a Q 10 of gating relaxations at negative potentials of â5. The Arrhenius plot of ClC-1 conductance at low pH had a clear break point
at â25 °C, with higher Q 10 values at lower temperatures.
The temperature sensitivity of relaxation and open probability of the slow gate, which in both ClC-0 and ClC-1 controls two
pores simultaneously, implies that the slow gating of ClC-1 is mechanistically different from that of ClC-0. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1111/j.1469-7793.2001.t01-1-00083.x |