Abstract: AimTo investigate the effects of K⁺ channel blockers on arsenic trioxide-induced HeLa cell death. MethodsViability of HeLa cells was assessed by mitochondrial dehydrogenase activity using colorimetric MTT assay and the voltage-dependent K⁺ currents were recorded by using patch-clamp technique. ResultsExposure of As₂O₃ (5 μmol·L^-1) for 24 h caused marked HeLa cell death. The rest living cells after As₂O₃ 24 h-incubation showed significant increase of K⁺ currents densities. At +80 mV, the densities of K⁺ currents (61±18) pA/10 pF (n=8) in As₂O₃ 24 h-incubation group were significantly more than that in the control group (38±10) pA/10 pF (n=8, P<005). The HeLa cells were prevented partially from As₂O₃-induced cell death by co-application for 24 h with typical voltage-dependent K⁺ channel blockers, 4-aminopyridine (3 mmol·L^-1) or tetraethylammonium (5 mmol·L^-1). 4-Aminopyridine (3 mmol·L^-1) or tetraethylammonium (5 mmol·L^-1) did not show any toxic effects on HeLa cells. ConclusionChronic treatment with As₂O₃ increased voltage-dependent K⁺ currents in HeLa cells and the cell death induced by As₂O₃ was reduced partially by voltage-dependent K⁺ channel blockers, 4-aminopyridine or tetraethylammonium.