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Activation of chloride current and decrease of cell volume by ATP in nasopharyngeal carcinoma cells

He Qingfeng, Chen Lixin, Mao Jianwen, Sun Xuerong, Li Pan, Zhong Ping, Nie Sihuai, Jacob T, Wang Liwei

Laboratory of Cell Biology,Guangdong Medical College.Zhanjiang 524023,Guangdong；China；School of Biosciences,Cardiff University,Cardiff CF10 3US

Abstract

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 (-0.9mv). 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 purinergic receptor antagonist reaction blue 2 by (67.39±5.06)%. ATP (50#mu#mol/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 purinergic receptor P2Y.

Key words: chloride channels;adenosine triphosphate;receptors,purinergic;patch clamp technique;cell size

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Citing This Article：

He Qingfeng, Chen Lixin, Mao Jianwen, Sun Xuerong, Li Pan, Zhong Ping, Nie Sihuai, Jacob T, Wang Liwei. Activation of chloride current and decrease of cell volume by ATP in nasopharyngeal carcinoma cells. Acta Physiol Sin 2004; 56 (6): (in Chinese with English abstract).