Abstract
1. 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. 2. 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. 3. Increasing intracellular free Ca2+ by decreasing the concentration of EGTA in the pipette solution reduced the amplitude of the ATP-gated current. 4. 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). 5. Pretreatment with forskolin (10 μM), 8-bromoadenosine-3',5'-cyclophosphate (8-Br-cyclic AMP, 1 mM), 3-isobutyl-1-methylxanthine (IBMX, 1 mM) or phorbol-12-myristate-13-acetate (PMA, 1 μM) reversibly reduced the ATP-induced peak current. 6. The results are consistent with molecular biological data which indicate that P2X2 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 P2X2 purinoceptors can be functionally modulated by receptor phosphorylation.
Original language | English (US) |
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Pages (from-to) | 337-344 |
Number of pages | 8 |
Journal | British Journal of Pharmacology |
Volume | 124 |
Issue number | 2 |
DOIs | |
State | Published - 1998 |
Externally published | Yes |
Keywords
- ATP
- Cochlea
- Deiters' cells
- Phosphorylation
- Protein kinase A (PKA)
- Protein kinase C (PKC)
- Purinoceptor
- Voltage-clamp
ASJC Scopus subject areas
- Pharmacology