RESUMO
Objective To observe the distribution and metabolism of arsenic speciation in urine of rats exposed to different concentrations of dimethylaraenic acid (DMA) through drinking water.Methods Thrity six weaning Wistar rats were randomly divided into normal control,low-dose group and high-dose group,12 rats in each group(6 female and 6 male); average body weight of female rats was (60 ± 5)g,and male rats was (50 ± 5)g.All rats of the 3 groups were given DMA at concentrations of 0,100,200 mg/L,respectively,corresponding to their specific groups through drinking water for 10 weeks.Inorganic arsenic(iAs),monomethylarsenic acid(MMA),DMA and trimethylarsenic compound (TMA) in urine were measured by hydride generation trapping and ultrahypothermia coupled with atomic absorption spectrometry.Results After feeding for 10 weeks,the differences of rat urinary concentrations of iAs,MMA,DMA and TMA between normal control,low-dose group and high-dose group were statistically significant(x2 =25.441,25.942,25.751,17.767,all P＜ 0.01).Urinary concentrations of iAs,MMA and DMA(2.541,4.383,24.447 mg/L) of low-dose group were significant higher than those of normal control (0.784,0.000,0.743 mg/L,all P ＜ 0.05) ; iAs,MMA,DMA and TMA(3.978,7.186,35.112,4.518 mg/L) of high-dose group were significantly higher than those of normal control(0.784,0.000,0.743,0.000 mg/L,all P ＜ 0.05).The concentrations increased along with increasing doses of DMA concentrations in drinking water(all P ＜ 0.05).Conclusions After rats are exposed to DMA,most of the DMA are excreted in unchanged form in urine and a small portion of DMA is metabolized into TMA.