Proton-gated channels in PC12 cells.
Acid-sensing ion channels (ASICs) are expressed in various sensory and central neurons. The functional role of these channels remains elusive. Complex subunit combinations and lack of specific blockers for native receptors are likely to contribute to the difficulty of resolving the function of ASICs. Finding a neuronal cell line, which expresses a single population of ASICs, should prove to be useful in delineating the function of individual ASICs. Using patch-clamp, Ca(2+)-imaging, and RT-PCR techniques, we have explored the existence of ASICs in PC12 cells, a clonal neuronal cell line. Fast drops of extracellular pH activated transient inward currents in PC12 cells with pH(0.5) at 6.0-6.2. The ASICs in PC12 cells were selective for Na(+) with significant Ca(2+) permeability. Currents in PC12 cells were blocked by the nonselective ASIC blocker amiloride. PcTX1, a specific homomeric ASIC1a blocker, also blocked the ASIC currents with an IC(50) of approximately 1.5 nM. RT-PCR demonstrated the existence of ASIC1a transcript in both undifferentiated and nerve growth factor-differentiated PC12 cells. Our data suggest that PC12 cells likely contain a single population of functional proton-gated channel-homomeric ASIC1a. It might be an ideal neuronal cell line for the study of physiological and potential pathological roles of this key subunit of ASICs.
Chu
Xiang-Ping
XP
Robert S. Dow Neurobiology Laboratories, Legacy Research, Portland, Oregon 97232, USA.
Miesch
Jennifer
J
Johnson
Martha
M
Root
Leslie
L
Zhu
Xiao-Man
XM
Chen
Dexi
D
Simon
Roger P
RP
Xiong
Zhi-Gang
ZG
D062565:Acid Sensing Ion Channels; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D004232:Diuretics / Q000494:pharmacology; D025802:Electric Capacitance; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D016716:PC12 Cells; D010455:Peptides; D011522:Protons; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D013111:Spider Venoms / Q000494:pharmacology; D015854:Up-Regulation / Q000502:physiology
C568266:ASIC1 protein, human; C112231:ASIC3 protein, human; D062565:Acid Sensing Ion Channels; D004232:Diuretics; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C413209:PcTX1 protein, Psalmopoeus cambridgei; D010455:Peptides; D011522:Protons; D012333:RNA, Messenger; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013111:Spider Venoms; D000584:Amiloride; D012964:Sodium; D002118:Calcium