Two types of acid-sensing ion channel currents in rat hippocampal neurons.
Two types of acid-sensing ion channel (ASIC)-like currents in cultured rat hippocampal neurons were recorded and their characteristics were studied by using a whole-cell recording technique. The results revealed that the ASIC-like currents, induced by a quick drop of the extracellular pH, decayed with different time constants (tau) of 229 +/- 16 (Type I) and 1209 +/- 56 ms (Type II). The ASIC-like currents displayed different sensitivities to extracellular proton (pH0.5 was 6.17 +/- 0.04 for Type I and 5.70 +/- 0.07 for Type II) and amiloride, a specific ASIC channel blocker (IC50 was 1.19 +/- 0.37 microM for Type I and 0.14 +/- 0.02 microM for Type II). Among all the 360 recorded neurons, ASIC-like currents were induced in 314 neurons (87.2%). In the neurons expressing ASICs, Type I currents were evoked from 269 neurons (85.7%) and Type II currents were induced only from 45 neurons (14.3%). As these ASIC-like currents presented various electrophysiological and pharmacological properties, further experiments should be conducted to decipher the complex subunit composition of ASICs in the hippocampus.
Weng
Xie-Chuan
XC
Beijing Institute of Pharmacology & Toxicology, Beijing 100850, China.
Zheng
Jian-Quan
JQ
Gai
Xiao-Dan
XD
Li
Jin
J
Xiao
Wen-Bin
WB
D062565:Acid Sensing Ion Channels; D000143:Acids / Q000378:metabolism; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000145:classification* / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000145:classification* / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000145:classification* / Q000187:drug effects / Q000502:physiology*
D062565:Acid Sensing Ion Channels; D000143:Acids; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011522:Protons; D015222:Sodium Channels; D000584:Amiloride