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P2X receptors in cochlear Deiters' cells
Author(s) -
Chen Chu,
Bobbin Richard P
Publication year - 1998
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701848
Subject(s) - ibmx , purinergic receptor , adenosine , adenosine triphosphate , biophysics , forskolin , patch clamp , uridine triphosphate , reversal potential , ionotropic effect , chemistry , agonist , extracellular , biology , receptor , medicine , biochemistry , nucleotide , nmda receptor , gene
The ionotropic purinoceptors in isolated Deiters' cells of guinea‐pig cochlea were characterized by use of the whole‐cell variant of the patch‐clamp technique. Extracellular application of adenosine 5′‐triphosphate (ATP) induced a dose‐dependent inward current when the cells were voltage‐clamped at −80 mV. The ATP‐induced current showed desensitization and had a reversal potential around −4 mV. Increasing intracellular free Ca 2+ by decreasing the concentration of EGTA in the pipette solution reduced the amplitude of the ATP‐gated current. The order of agonist potency was: 2‐methylthioATP (2‐meSATP)>ATP>benzoylbenzoyl‐ATP (BzATP)>α,β‐methyleneATP (α,β,meATP>adenosine 5′‐diphosphate (ADP)>uridine 5′‐triphosphate (UTP)>adenosine 5′‐monophosphate (AMP)=adenosine (Ad). Pretreatment with forskolin (10 μ M ), 8‐bromoadenosine‐3′,5′‐cyclophosphate (8‐Br‐cyclic AMP, 1 m M ), 3‐isobutyl‐1‐methylxanthine (IBMX, 1 m M ) or phorbol‐12‐myristate‐13‐acetate (PMA, 1 μ M ) reversibly reduced the ATP‐induced peak current. The results are consistent with molecular biological data which indicate that P2X 2 purinoceptors are present in Deiters' cells. In addition, the reduction of the ATP‐gated current by activators of protein kinase A and protein kinase C indicates that these P2X 2 purinoceptors can be functionally modulated by receptor phosphorylation.