Dependence of the acid-sensitive ion channel, ASIC1a, on extracellular Ca(2+) ions

Brain Res. 2001 May 11;900(2):277-81. doi: 10.1016/s0006-8993(01)02345-9.


The early H(+)-induced current in the embryonic spinal cord neurone depends on extracellular Ca(2+) for its function. We have studied the Ca(2+)-dependence of homo- and heteromultimeric acid-sensing ion channels (ASICs) expressed in Cos cells. It was found that single-channel conductance of both the ASIC2a and the ASIC1a channel is reduced at membrane potentials more negative than -40 mV by elevated extracellular Ca(2+). Due to this effect on unitary currents, the macroscopic ASIC2a peak current at -60 mV decreases gradually with rising extracellular Ca(2+) concentration. In addition, the macroscopic ASIC1a current is very small at low extracellular Ca(2+) and increases with rising Ca(2+) up to 5 mM before decreasing again at still higher concentrations of extracellular Ca(2+).

MeSH terms

  • Acid Sensing Ion Channels
  • Amiloride / pharmacology
  • Animals
  • COS Cells
  • Calcium / metabolism*
  • Dose-Response Relationship, Drug
  • Electric Conductivity
  • Extracellular Space / metabolism*
  • Hydrogen-Ion Concentration
  • Ions
  • Membrane Potentials / physiology
  • Membrane Proteins*
  • Nerve Tissue Proteins*
  • Osmolar Concentration
  • Protein Isoforms / metabolism
  • Protein Isoforms / physiology
  • Sodium Channel Blockers
  • Sodium Channels / drug effects
  • Sodium Channels / metabolism*
  • Sodium Channels / physiology


  • ASIC1 protein, human
  • ASIC3 protein, human
  • Acid Sensing Ion Channels
  • Ions
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Protein Isoforms
  • Sodium Channel Blockers
  • Sodium Channels
  • Amiloride
  • Calcium