Abstract: Objective To research protective effects of trisodium phosphate on Vero cells exposed to NaAsO₂.Methods After treatment of NaAsO₂,the Vero cells were cultured in nutrient fluid with different dosages of trisodium phosphate.The activity of Na⁺,K⁺ ATP ase in Vero cell membrane were measured with spectrophotometric.The contents of membrane phospholipids in Vero cells were detected with high-performance liquid chroma to graphy (HPLC).Results NaAsO₂ (2.20 mg/L) inhibited the activity of Na⁺,K⁺ ATPase in Vero cell membrane.Trisodium phosphate at high dosag e (69.00 mg/L) increased the activity of Na⁺,K⁺ ATPase (0.761±0.067 μU prot/h) compared with that of the control group(0.544±0.037 μU prot/h,P < 0.05).Meanwhile,The contents of four main components of membrane phospholipids in Vero cells were decreased with NaAsO₂ (2.20 mg/L) exposure.Trisod iumphosphate (69 00 mg/L) increased the contents of membrane phospholipids.Phosphatidy lcholine,phosphatidy lethano-lamine,phosphatidy lserin,and sphingm yelin in Vero cells were 0.506±0.073,0.101±0.237,0.083±0.005,and 0.066±0.003,respectively,and significantly higher than those of the control group (P < 0.05 for all).Conclusion Trisodium phosphate intervention at a certain dose could protect cells exposed to NaAsO₂ from changes of Na⁺,K⁺ ATPase activity and phospholipds content of the membrane.