Activation of chloride current and decrease of cell volume by ATP in nasopharyngeal carcinoma cells.
Whole-cell patch clamp and cell volume measurement techniques were used to investigate the ATP-activated chloride current and the ATP effect on cell volume in nasopharyngeal carcinoma cells. Extracellular application of ATP in micromolar concentrations activated a current with the properties of modest outward rectification and negligible time-dependent inactivation in a dose-dependent manner. The current reversed at a potential [(-0.05+/-0.03) mV] close to the Cl- equilibrium potential (-0.9 mV). Substitution of Cl- with gluconate in the extracellular solution decreased the ATP-activated current and shifted the reversal potential positively. NPPB, one of the chloride channel blockers, inhibited the current by (81.03+/-9.36)%. The current was also depressed by the P2Y purinoceptor antagonist, reactive blue 2, by (67.39+/-5.06)%. ATP (50 micromol/L) decreased the cell volume under the isotonic condition. Depletion of extracellular and intracellular Cl- abolished the ATP effect on cell volume. The results suggest that extracellular ATP of micromolar scales can induce a chloride current associated with cell volume regulation by activation of chloride channel through binding to purinoceptor P2Y.
He
Qing-Feng
QF
Laboratory of Cell Biology, Guangdong Medical College, Zhanjiang 524023, China.
Wang
Li-Wei
LW
Mao
Jian-Wen
JW
Sun
Xue-Rong
XR
Li
Pan
P
Zhong
Ping
P
Nie
Si-Huai
SH
Jacob
Tim
T
Chen
Li-Xin
LX
D000255:Adenosine Triphosphate / Q000502:physiology*; D048429:Cell Size / Q000187:drug effects*; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000378:metabolism / Q000473:pathology*; D009579:Nitrobenzoates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D014407:Tumor Cells, Cultured
D018118:Chloride Channels; D009579:Nitrobenzoates; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D000255:Adenosine Triphosphate