Objective     To investigate the reversal of apoptosis resistance of adriamycin-resistant human bladder carcinoma cell line BIU-87/ADM by tetrandrine and its possible mechanism.     Methods      Adriamycin-resistant and adriamycin-susceptible human bladder carcinoma cell lines were each divided into a control group

a tetrandrine group

an adriamycin group

and an adriamycin and tetrandrine combination group. The action concentrations

of adriamycin and tetrandrine were 1.5 μg/ml and 1 μg/ml

respectively. Cell apoptosis was detected by AO/EB staining combined with fluorescence microscopy. The changes of cell mitochondrial membrane potential were measured by JC-1. The expression levels of Bcl-2 and Bax genes were determined by immunocytochemistry as well as RT-PCR.     Results      After 24 h action

the apoptosis rates of adriamycin group and adriamycin and tetrandrine combination group of adriamycin-resistant cell line were 15.33±2.58% and 43.17±3.49%

respectively. Clearly the latter had a significantly higher apoptosis rate than the former (

P

<

0.01). Those of adriamycin-susceptible cell line

however

were 57.83±5.64% and 59.17±5.38%

respectively. There was no remarkable difference between the two groups (

P

>0.05). Moreover

the expression level of Bcl-2 gene decreased

while that of Bax gene increased in the adriamycin and tetrandrine combination group of adriamycin-resistant cell line (

P

<

0.05). The cell mitochondrial membrane potential decreased significantly in the adriamycin and tetrandrine combination group of adriamycin-resistant cell line.      Conclusion    Tetrandrine can effectively reverse the apoptosis resistance of adriamycin-resistant human bladder carcinoma cell line BIU-87/ADM by down-regulating Bcl-2 gene expression

up-regulating Bax gene expression

as well as decreasing cell mitochondrial membrane potential.