Mechanosensitivity of N-type calcium channel currents

Biophys J. 2002 Nov;83(5):2560-74. doi: 10.1016/S0006-3495(02)75267-3.

Abstract

Mechanosensitivity in voltage-gated calcium channels could be an asset to calcium signaling in healthy cells or a liability during trauma. Recombinant N-type channels expressed in HEK cells revealed a spectrum of mechano-responses. When hydrostatic pressure inflated cells under whole-cell clamp, capacitance was unchanged, but peak current reversibly increased ~1.5-fold, correlating with inflation, not applied pressure. Additionally, stretch transiently increased the open-state inactivation rate, irreversibly increased the closed-state inactivation rate, and left-shifted inactivation without affecting the activation curve or rate. Irreversible mechano-responses proved to be mechanically accelerated components of run-down; they were not evident in cell-attached recordings where, however, reversible stretch-induced increases in peak current persisted. T-type channels (alpha(1I) subunit only) were mechano-insensitive when expressed alone or when coexpressed with N-type channels (alpha(1B) and two auxiliary subunits) and costimulated with stretch that augmented N-type current. Along with the cell-attached results, this differential effect indicates that N-type mechanosensitivity did not depend on the recording situation. The insensitivity of T-type currents to stretch suggested that N-type mechano-responses might arise from primary/auxiliary subunit interactions. However, in single-channel recordings, N-type currents exhibited reversible stretch-induced increases in NP(o) whether the alpha(1B) subunit was expressed alone or with auxiliary subunits. These findings set the stage for the molecular dissection of calcium current mechanosensitivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Barium / chemistry
  • Brain / metabolism
  • Calcium Channels, N-Type / chemistry*
  • Calcium Channels, N-Type / metabolism
  • Cell Line
  • Cell Membrane / metabolism
  • DNA, Complementary / metabolism
  • Electrophysiology
  • Humans
  • Kinetics
  • Microscopy, Video
  • Neurons / metabolism
  • Normal Distribution
  • Patch-Clamp Techniques
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Time Factors

Substances

  • Calcium Channels, N-Type
  • DNA, Complementary
  • Recombinant Proteins
  • Barium