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, Medical College, Jinan University, Guangzhou 510632, China.
Sheng Li Xue Bao. 2012 Dec 25;64(6):673-80.
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.
本研究旨在探讨熊果酸对鼻咽癌细胞（CNE-2Z）氯离子通道及细胞体积的影响。采用全细胞膜片钳技术检测电流，应用细胞成像技术测量细胞体积。通过改变细胞外渗透压、替换细胞外阴离子以及应用氯离子通道阻滞剂，研究熊果酸诱导电流的特性。结果表明，在等渗条件下，背景电流微弱且稳定。用熊果酸（100 nmol/L）灌注细胞时，可诱导出大电流（在-80 mV时为-59.86 pA/pF±4.86 pA/pF，在+80 mV时为78.92 pA/pF±6.39 pA/pF）。氯离子电流呈外向整流，且时间和电压依赖性失活可忽略不计。电流的反转电位（-4.83 mV±0.30 mV）接近计算得出的Cl⁻平衡电位（-0.9 mV）。该通道对不同阴离子的通透性排序如下：Cl⁻ = I⁻ > Br⁻ > 葡萄糖酸盐。高渗溶液抑制熊果酸诱导的电流。氯离子通道阻滞剂他莫昔芬（20 μmol/L）和5-硝基-2-（3-苯丙基氨基）苯甲酸（NPPB，100 μmol/L）可抑制该电流。此外，熊果酸在1小时内可使细胞体积减少（11.78±1.20）%，且该效应被NPPB抑制。这些结果表明，熊果酸可激活氯离子通道，导致鼻咽癌细胞中Cl⁻外流及细胞体积减小。
