gluconate in both G1 phase and S phase cells.The permeability of G1 phase cells to I-was higher than that in S phase cells,but to gluconate was lower than that in S phase cells.CONCLUSIONS: The density of the volume-activated Cl-current,the anion permeability of the channel and the sensitivity of the current to tamoxifen were different between the CNE-2Z cells in G1 phase and those in S phase.The results suggest that the expression of tamoxifen-sensitive,volume-activated chloride channels is differentiated at different stages of the cell cycle.

AIM: The roles of Cl-channels in regulatory volume decrease (RVD), cell proliferation and cell cycle progression in nasopharyngeal carcinoma cells (CNE-2Z) were investigated. METHODS: Image analysis of living cells was used to detect the volume changes following exposure to hypotonic solutions. Cell viability was determined by the trypan blue assay. MTT method was applied to detected cell proliferation. The effect of the blocker on the cell cycle distribution was monitored by the flow cytometry. RESULTS: 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) inhibited RVD and cell proliferation in a dose-dependent manner. NPPB at the concentration of 100 ?mol/L arrested cells in G 1 phase (G 1 population increased from 54% to 71% at 48 h after treatments), but did not significantly alter cell viability. CONCLUSION: Block of chloride channels suppressed cell proliferation by arresting cells in G 1 phase. The results suggest that activation of Cl-channels and RVD is necessary for facilitating cells to proceed to the S phase from G 1 phase and maintaining cell proliferation.

S. The migration of CNE-2Z cells was inhibited by chloride channel blockers (ATP, NPPB and tamoxifen), but the inhibitory effect of the blockers varied with cells at different stages. CONCLUSIONS: The migratory ability is associated with the cell cycle in CNE-2Z cells. Chloride channels play an important role in cell migration of CNE-2Z cells.

AIM: To clarify the role of Cl - in regulatory volume decrease (RVD) of nasopharyngeal carcinoma cells (CNE-2Z).METHODS: Analysis of living cell images was used to detect the volume changes following exposure to hypotonic solution. Iron replacement and block of iron channels were also applied in the present study. RESULTS: Extracelluar hypotonic treatment made the cells swell and induced RVD. The RVD was correlated positively to the swelling in the range of 160-230 mOsmol/L. Substitution of gluconate for Cl - in perfusing solutions markedly increased RVD. Depletion of cellular Cl - abolished, and chloride channel blockers inhibited RVD. CONCLUSION: Cl - is the key iron to establish the RVD in CNE-2Z cells. Activation of Cl - channels and Cl - efflux are the major mechanisms of RVD.