Objective:To investigate the effects of oxymartine on cell growth and the changes of P-glycoprotein in HNE-1 cell line after exposed to fractionated X-irradiation.Methods:By MTT

the cell proliferation was observed both before X-irradiation and after X-irradiation conditions with the extent of vincristine

oxymartine and verapamil respectively.P-glycoprotein expression was tested by immunohistochemistory method SP.Results:(1)Vincristine

oxymartine and verapamil were capable of inhibiting cell growth on HNE-1 cell line and fractionated X-irradiated HNE-1(200)cell subline;(2)Vincristine was less inhibitory on cell growth in HNE-1(200)cell subline than HNE-1 cell line

and the difference had statistic significance;(3)P-glycoprotein expression in HNE-1 cell line was negative while HNE-1(200)cell subline positive;oxymartine with low inhibitory concentration could increase the expression of P-glycoprotein in HNE-1(200) cell subline

which is similar to that of verapamil.Conclusion:(1)Oxymartine is capable of inhibiting cell growth on HNE-1 cell line and fractionated X-irradiated HNE-1(200)cell subline;(2)HNE-I(200)cell subline is resistant to vincristine;(3)Oxymartine with low inhibitory concentration could increase the expression of P-glycoprotein in HNE-1(200)cell subline.which is similar to that of verapamil.