| Polybrominated diphenyl ethers(PBDEs) are a class of typical persistent organic pollutants(POPs). Because of their high lipophilicity, they are persistent with potential for bioaccumulation in organisms and biomagnification through food chains. As a result, they can cause adverse effects on the ecosystem and human body. Up to now, PBDEs have been detected in adipose tissue and human tissue.Oral ingestion is the main pathway of PBDE exposure to human. The uptake of PBDEs primarily occurs in the small intestine which is also the main barrier of xenobiotics. The aim of this study was to investigate the transport and mechanism of PBDEs using a Caco-2 cell monolayer model. Within the range of exposure time(4-24 h), a linerar relationship was observed between the transport of PBDEs from BL to AP and the expourse time at the concentration of 10 ng/mL. The transport and intracellular accumulation ratios of the PBDE congeners varied. The transport ratios had a negative linear correlation to the logKOW values. Meanwhile, with the increasing of logKOW, the intracellular ratios increased and then decreased. There was a parabolic relationship between the intracellular ratios and the logKOW values. The results showed that the transport ratios for both directions significantly decreased at low temperature, indicating that the energy-dependent transport mechanism was involed the transport processes. Verapamil, MK571, and Ko143 were choosed as the inhibitors of P-gp, MRP, and BCRP, respectively, to investigate whether the efflux transporter involved in the transport. The results indicated that the efflux transporters might participate the transport. In addition, an influx transporter(Organic Cation Transporters, OCTs) was also investigated using an inhibitor of cimetidine. The result showed that cimetidine could decrase the transport of PBDEs in AP-BL direction, which indicated that OCTs might be involved in the transport of PBDEs also. |
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