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Mechanosensitivity of Na v 1.5, a voltage‐sensitive sodium channel
Author(s) -
Beyder Arthur,
Rae James L.,
Bernard Cheryl,
Strege Peter R.,
Sachs Frederick,
Farrugia Gianrico
Publication year - 2010
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2010.199034
Subject(s) - mechanosensitive channels , sodium channel , biophysics , conductance , chemistry , electrophysiology , voltage , sodium , ion channel , physics , biochemistry , biology , neuroscience , condensed matter physics , receptor , organic chemistry , quantum mechanics
The voltage‐sensitive sodium channel Na v 1.5 (encoded by SCN5A ) is expressed in electromechanical organs and is mechanosensitive. This study aimed to determine the mechanosensitive transitions of Na v 1.5 at the molecular level. Na v 1.5 was expressed in HEK 293 cells and mechanosensitivity was studied in cell‐attached patches. Patch pressure up to −50 mmHg produced increases in current and large hyperpolarizing shifts of voltage dependence with graded shifts of half‐activation and half‐inactivation voltages (Δ V 1/2 ) by ∼0.7 mV mmHg −1 . Voltage dependence shifts affected channel kinetics by a single constant. This suggested that stretch accelerated only one of the activation transitions. Stretch accelerated voltage sensor movement, but not rate constants for gate opening and fast inactivation. Stretch also appeared to stabilize the inactivated states, since recovery from inactivation was slowed with stretch. Unitary conductance and maximum open probability were unaffected by stretch, but peak current was increased due to an increased number of active channels. Stretch effects were partially reversible, but recovery following a single stretch cycle required minutes. These data suggest that mechanical activation of Na v 1.5 results in dose‐dependent voltage dependence shifts of activation and inactivation due to mechanical modulation of the voltage sensors.