Mechanosensitivity of Nav1.5, a voltage-sensitive sodium channel

J Physiol. 2010 Dec 15;588(Pt 24):4969-85. doi: 10.1113/jphysiol.2010.199034. Epub 2010 Nov 1.

Abstract

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 (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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Electric Conductivity*
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Ion Channel Gating
  • Mechanotransduction, Cellular / physiology*
  • NAV1.5 Voltage-Gated Sodium Channel
  • Patch-Clamp Techniques
  • Sodium Channels / metabolism*

Substances

  • NAV1.5 Voltage-Gated Sodium Channel
  • SCN5A protein, human
  • Sodium Channels