Chloride currents activated by cisplatin in poorly differentiated naso-pharyngeal carcinoma cells are not Ca2+-activated chloride currents

AIM：To investigate the type of chloride channel activated by cisplatin in poorly differentiated nasopharyngeal carcinoma cells (CNE-2Z cells). METHODS：The technique of whole-cell patch-clamp was used to investigate the role of Ca2+ 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 calcium. 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.