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[Ursolic acid activates chloride channels and decreases cell volume in poorly differentiated nasopharyngeal carcinoma cells.] [Article in Chinese]

LI Bing-Xue, TENG Shuang-Feng, LIU Zhen-Feng, LIU Mei, Ye Dong, MA Lian-Shun, ZHU Lin-Yan, WANG Li-Wei, CHEN Li-Xin

Department of Pharmacology； Department of Physiology, Medical College, Jinan University, Guangzhou 510632, China

Abstract

The present study aimed to investigate the effects of ursolic acid on the chloride channels and cell volume in nasopharyngeal carcinoma cells (CNE-2Z). The whole-cell patch clamp technique was used to detect the current, and cell imaging technique was applied to measure cell volume. The properties of the currents induced by ursolic acid were investigated by changing the extracellular osmotic pressure, replacing the extracellular anions and applying chloride channel blockers. The results showed that, under isotonic conditions, the background current was weak and stable. When perfusing the cells with ursolic acid (100 nmol/L), a large current (-59.86 pA/pF ± 4.86 pA/pF at -80 mV, 78.92 pA/pF ± 6.39 pA/pF at +80 mV) was induced. The chloride current showed outward rectification and negligible time- and voltage-dependent inactivation. The reversal potential (-4.83 mV ± 0.30 mV) of the current was close to the calculated equilibrium potential for Cl(-) (-0.9 mV). The permeabilities of the channel to different anions were ranked in order as follows: Cl(-) = I(-) > Br(-) > gluconate. Hypertonic solutions inhibited the current induced by ursolic acid. The chloride channel blockers, tamoxifen (20 μmol/L) and 5-nitro-2-(3-phenylpro-pylamino) benzoic acid (NPPB, 100 μmol/L), suppressed the current. Furthermore, ursolic acid decreased the cell volume by (11.78 ± 1.20)% in 1 h, and the effect was inhibited by NPPB. These results suggest that ursolic acid can activate chloride channels, resulting in outflow of Cl(-) and decrease of cell volume in nasopharyngeal carcinoma cells.

Key words: Ursolic acid; nasopharyngeal carcinoma cells; chloride channels; patch-clamp techniques; cell volume;

Received: 2012-04-13　　Accepted: 2012-08-27

Corresponding author: 王立伟,陈丽新　　E-mail: chenlixinw@sohu.com,wangliweic@sohu.com

Citing This Article：

LI Bing-Xue, TENG Shuang-Feng, LIU Zhen-Feng, LIU Mei, Ye Dong, MA Lian-Shun, ZHU Lin-Yan, WANG Li-Wei, CHEN Li-Xin. [Ursolic acid activates chloride channels and decreases cell volume in poorly differentiated nasopharyngeal carcinoma cells.] [Article in Chinese]. Acta Physiol Sin 2012; 64 (6): 673-680 (in Chinese with English abstract).