Existence and distinction of acid-evoked currents in rat astrocytes.
Astrocytes are vital structures that support and/or protect neighboring neurons from pathology. Although it is generally accepted that glutamate receptors mediate most astrocyte effects, acid-evoked currents have recently attracted attention for their role in this regard. Here, we identified the existence and characteristics of acid-sensing ion channels (ASICs) and the transient receptor potential vanilloid type 1 (TRPV1) in astrocytes. There were two types of currents recorded under the application of acidic solution (pH 6.0) in cultured rat astrocytes. Transient currents were exhibited by 10% of the astrocytes, and sustained currents were exhibited by the other 90%, consistent with the features of ASIC and TRPV1 currents, respectively. Western blotting and immunofluorescence confirmed the expression of ASIC1, ASIC2a, ASIC3, and TRPV1 in cultured and in situ astrocytes. Unlike the ASICs expressed in neurons, which were mainly distributed in the cell membrane/cytoplasm, most of the ASICs in astrocytes were expressed in the nucleus. TRPV1 was more permeable to Na(+) in cultured astrocytes, which differed from the typical neuronal TRPV1 that was mainly permeable to Ca(2+). This study demonstrates that there are two kinds of acid-evoked currents in rat astrocytes, which may provide a new understanding about the functions of ligand-gated ion channels in astrocytes.
Huang
Chao
C
Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Hu
Zhuang-Li
ZL
Wu
Wen-Ning
WN
Yu
Dan-Fang
DF
Xiong
Qiu-Ju
QJ
Song
Jian-Ren
JR
Shu
Qing
Q
Fu
Hui
H
Wang
Fang
F
Chen
Jian-Guo
JG
D062565:Acid Sensing Ion Channels; D000143:Acids / Q000494:pharmacology*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000145:classification / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000145:classification / Q000378:metabolism; D050916:TRPV Cation Channels / Q000378:metabolism
C568269:ASIC3 protein, rat; D062565:Acid Sensing Ion Channels; D000143:Acids; C568268:Asic1 protein, rat; D009419:Nerve Tissue Proteins; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D000584:Amiloride; C071423:capsazepine; D002211:Capsaicin; D002118:Calcium