ABSTRACT
Aim To investigate the effect of gelsemium alkaloids on chloride channels and cell volume in he-patic carcinoma cells. Methods The time-lapse live cell imaging and whole-cell patch clamp techniques were used respectively to detect the volume changes and currents induced by gelsemium alkaloids in HepG2 cells. Results It was found that the cell volume was decreased by (12. 48 ± 2. 2) % (P<0. 01) when ex-posed to gelsemium alkaloids for 50 min and this phe-nomenon could be inhibited by the chloride channel blocker tamoxifen. It was shown by whole-cell patch clamping that a chloride current could be evoked by extracellular application of gelsemium alkaloids ( 2μmol·L-1 ) . The current was outward-rectified with-out obvious voltage- and time-dependent inactivation. The reversal potential of the current was ( -3. 21 ± 0. 67) mV ,which was close to the equilibrium poten-tial of chloride. The extracellular application of the chloride blockers, tamoxifen and 5-notro-2-(3-phenyl-propylamino)benzoic acid (NPPB), and 47% hyper-tonic solution inhibited the current significantly ( P <0. 01 ) . Conclusion Gelsemium alkaloids could acti-vate chloride channels and induce a volume decrease ( named apoptotic volume decrease, AVD) , and these effect could be inhibited by chloride channel blockers. The results suggest that the chloride channel can be one of the targets of gelsemium alkaloids in their anti-cancer action.
ABSTRACT
Aim To clarify the effect of Borneol on the chloride channels and cell volume in poorly differentia-ted nasopharyngeal carcinoma CNE-2Z cells.Methods The technique of whole-cell patch clamp was used to detect the chloride currents and analyze the character-istics of the currents in CNE-2Z cells.The volume changes caused by Borneol were measured by the meth-od of time-lapse live cell imaging.Results The chlo-ride currents were induced by extracellular application of Borneol (20 μmol·L -1 )isotonic condition.The currents showed a characteristic of outward rectification and did not show voltage-dependent or time-dependent inactivation.The reversal potential of the currents was close to the CI-equilibrium potential. The currents were inhibited by the chloride channel blocker tamox-ifen.The currents were also inhibited by 47% hyper-tonic solution.Borneol decreased the cell volume by 9.4% in 30 min.Tamoxifen completely inhibited the Borneol-induced cell volume decrease.Conclusion Borneol can activate volume-sensitive chloride channels and induce volume decrease in CNE-2Z cells.Chloride channels play a pivotal role in the process of volume decrease caused by Borneol.
ABSTRACT
AIM:To study the effects and mechanisms of ethanol on chloride channels in poorly differentiated nasopharyngeal carcinoma CNE-2Z cells.METHODS:The effect of ethanol on the cell growth was analyzed by MTT as-say.The technique of whole-cell patch-clamp was used to detect the chloride current .The characteristics of the chloride current were analyzed by using the chloride channel blockers .The siRNA technique was used to analyze the molecular basis of the ethanol-sensitive chloride channels .RESULTS: Under isotonic conditions , the background current was weak and stable.Ethanol at concentrations of 0.17~170 mmol/L activated a chloride current in a concentration-dependent manner (an inverted U-shape), with a maximum effect at the concentration of 17 mmol/L.The currents showed obviously outward rectification and were susceptible to extracellular hypertonicity and the chloride channel blocker , 5-nitro-2-(3-phenylpropyl-amino) benzoic acid ( NPPB) .ClC-3 siRNA obviously decreased the currents activated by ethanol .CONCLUSION:Ex-tracellular ethanol induces chloride currents through activating the ClC-3 chloride channels .
ABSTRACT
AIM:To investigate the type of chloride channel activated by cisplatin in poorly differentiated na -sopharyngeal carcinoma cells (CNE-2Z cells).METHODS:The technique of whole-cell patch-clamp was used to investi-gate the role of Ca 2+in the activation of cisplatin-activated chloride currents and to analyze the effect of hypertonic stress on these currents in CNE-2Z cells.RESULTS:Chloride currents were induced when the cells were exposed to the calcium -free cisplatin solution , showing the similar density to the currents induced by cisplatin with the presence of extracellular cal -cium.However , the latency and the peak time of cisplatin-activated currents in the absence of extracellular calcium were prolonged.The activation of cisplatin-activated chloride currents was insensitive to the depletion of intra-and extracellular calcium.Calcium channel antagonist nifedipine had no effect on the cisplatin -activated chloride currents , while hypertonic solution completely inhibited those currents .CONCLUSION:The cisplatin-activated chloride currents are independent on intra/extracellular calcium .The chloride channels activated by cisplatin are not calcium-activated chloride channels , but are probably volume-sensitive chloride channels .