Osmotic swelling activates a novel anionic current with VRAC-like properties in a cytoplasmic droplet membrane from Phycomyces blakesleeanus sporangiophores

Res Microbiol. 2015 Apr;166(3):162-73. doi: 10.1016/j.resmic.2015.02.004. Epub 2015 Feb 18.

Abstract

We describe here whole-cell currents of droplets prepared from the apical region of growing Phycomyces blakesleeanus sporangiophores. Whole-cell current recordings revealed the osmotically activated, outwardly rectifying, fast inactivating instantaneous current (ORIC) with biophysical properties closely resembling volume-regulated anionic current (VRAC). ORIC is activated under conditions of osmotically induced swelling and shows strong selectivity for anions over cations. In addition, ORIC shows voltage and time-dependent inactivation at positive potentials and recovery from inactivation at negative potentials. ORIC is blocked by anthracene-9-carboxylic acid, an anion channel blocker, in a voltage-dependent manner. This is the first report of the presence of VRAC-like current in an organism outside the chordate lineage.

Keywords: A-9-C; Filamentous fungi; Outward rectifier; Voltage-dependent inactivation; Whole-cell patch-clamp.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracenes / pharmacology
  • Cell Membrane / physiology*
  • Ion Channel Gating
  • Ion Channels / physiology*
  • Membrane Potentials*
  • Osmotic Pressure*
  • Patch-Clamp Techniques
  • Phycomyces / physiology*

Substances

  • Anthracenes
  • Ion Channels
  • 9-anthroic acid