Abstract: 【Objective】 This study investigated the effect of Baicalein on cisplatin cytotoxicity and the relationship between this effect and the modulation of gap junction (GJ) function in Cx32 transfected HeLa cell line. 【Methods】 SRB assay was used to examine the effect of baicalein on cell viability. Parachute assay was used to investigate the effect of baicalein on GJ function. The effect of baicalein on cisplatin cytotoxicity and the relationship of this effect and GJ function were assayed by standard colony-forming assay. The expression of Cx32 was monitored by Western blotting. 【Results】 Baicalein 24 h had no effect on cell viability below 100 μmol/L. Baicalein 0.0125 ~ 0.1 μmol/L 4 h dose dependently increased dye spread through gap junction. Baicalein 0.1 ?滋M increased GJ function mostly at 4 h. Baicalein decreased clonogenic survival fraction at high cell density (GJ formed) induced by cisplatin. Baicalein had no effect on cisplatin cytotoxicity at low-density cell cultures (no GJ formed) or using GJ inhibitor oleamide. Doxycycline could induct connexin expression and GJ formation. At high cell density

non-Cx32 expression (no GJ formed) could reduce the enhancement of cisplatin cytotoxicity induced by baicalein compared with Cx32 expression cells (GJ formed). In contrast

at low cell density (no GJ formed no matter Cx expression or not)

Cx expression change did not have this effect. Western blotting results showed different concentration (0.0125-0.1) ?滋mol/L of baicalein 4 h had no effect on Cx32 expression. Cx32 expression did not change when treated with baicalein 0.1 ?滋mol/L from 4 h to 24 h. 【Conclusion】 Baicalein improved cisplatin cytotoxicity in HeLa32 cells by improving GJ function in HeLa32 cells. The improvement of GJ function in HeLa32 cells by baicalein did not accompany Cx32 expression change.