Roles Of K~+ Channels In Volume Regulatory And Apoptosis In Nasopharyngeal Carcinoma Cells

Objective:1) To investigate the roles of potassium channel in volume regulatory of nasopharyngeal carcinoma (CNE-2Z) cells; 2) To analyse the effect of 23-Hydroxybetulinic acid on apoptosis and proliferation of CNE-2Z cells; 3) To explore the roles of 23-Hydroxybetulinic acid in the activation of potassium channel.Methods:1) The whole-cell patch clamp technique was used to record currents; 2) The Q500MC image processor and analysis softwares were used to detect the diameter and volume; 3) Cell proliferation was tested by the MTT assay; 4) The apoptosis was analysed by the flow cytometry.Results:47% hypotonic challenges induced RVD and actived a volume-activated potassium current. The potassium current and RVD were inhibited by the calcium-dependent potassium channel blocker, clotrimazole, almost entirely. Depletion of extracellluar calcium, hypotonic challenges could not active a potassium current, and RVD significantly reduced. The voltage-gated potassium channel blocker,4-AP, partially inhibited the potassium current.23-Hydroxybetulinic acid (100μmol/L) activated a potassium current. The current could be inhibited by clotrimazole (100μmol/L) and 4-AP (5 mmol/L).23-Hydroxybetulinic acid induced apoptosis of CNE-2Z cells, and blocked the cell cycle in S phase. Cell proliferation were also inhibited by 23-Hydroxybetulinic acid.Conclusion:1) CNE-2Z cells have the capability of RVD. The volume-activated potassium was very important to RVD. Ca2+ -dependent potassium channel was the main component of volume-activated potassium channels and played an important role in volume regulation of CNE-2Z cell. The voltage-gated potassium channels may also contribute in part to it.3) 23-Hydroxybetulinic acid which could active potassium channels of CNE-2Z cells induced apoptosis and blocked cell cycle in S phase and inhibited the proliferation. The potassium channel actived by 23-Hydroxybetulinic acid may play an important role in the apoptosis induced by 23-Hydroxybetulinic acid.