Yang Ching-Hui, Glover Kyle P, Han Xing
DuPont Haskell Global Centers for Health & Environmental Sciences, Newark, DE 19714, USA.
Toxicol Lett. 2009 Oct 28;190(2):163-71. doi: 10.1016/j.toxlet.2009.07.011. Epub 2009 Jul 16.
Organic anion transporting polypeptide (Oatp) 1a1 has been hypothesized to play a key role in rat renal reabsorption of perfluorooctanoate (PFO). We have investigated PFO uptake kinetics in Chinese Hamster Ovary (CHO) cells that have been stably transfected with the cDNA encoding Oatp1a1. The Oatp1a1-expressing CHO cells have been validated by their Oatp1a1 gene expression, estrone-3-sulfate (E3S) uptake kinetics, and the correlation between Oatp1a1 gene expression and E3S uptake activity that were both induced by the treatment of sodium butyrate. Oatp1a1-mediated PFO uptake underwent a saturable process with a K(m) value of 162.2+/-20.2microM, which was effectively inhibited by known Oatp1a1 substrates sulfobromophthalein and taurocholate, and a major flavonoid in grapefruit juice, naringin. The inhibition of Oatp1a1-mediated E3S uptake has been compared for linear perfluorocarboxylates with carbon chain lengths ranged from 4 to 12. There was no apparent inhibition by perfluorobutanoate and perfluoropentanoate at 1mM. Inhibition was observed for perfluorohexanoate at 1mM and the level of inhibition increased as the increase of the chain length up to perfluorodecanoate. The values of apparent inhibition constant (K(i,app)) were determined for perfluorocarboxylates with chain lengths between 6 and 10. The log values of K(i,app) exhibited a negative linear relationship to the chain lengths and a positive linear relationship to the log values of the total clearance of perfluorocarboxylates in male rats. This in vitro-to-in vivo correlation strongly supports a tubular reabsorptive role of Oatp1a1 in rat renal elimination of perfluorocarboxylates. Due to the sex-dependent expression of Oatp1a1 in rat kidney, Oatp1a1-mediated tubular reabsorption is suggested to be the mechanism for the sex-dependent renal elimination of PFO in rats.
有机阴离子转运多肽（Oatp）1a1被认为在大鼠肾脏对全氟辛酸（PFO）的重吸收中起关键作用。我们研究了稳定转染了编码Oatp1a1的cDNA的中国仓鼠卵巢（CHO）细胞对PFO的摄取动力学。通过Oatp1a1基因表达、硫酸雌酮（E3S）摄取动力学以及丁酸钠处理诱导的Oatp1a1基因表达与E3S摄取活性之间的相关性，对表达Oatp1a1的CHO细胞进行了验证。Oatp1a1介导的PFO摄取经历了一个可饱和过程，K（m）值为162.2±20.2μM，已知的Oatp1a1底物磺溴酞钠和牛磺胆酸盐以及葡萄柚汁中的一种主要类黄酮柚皮苷可有效抑制该过程。比较了碳链长度为4至12的直链全氟羧酸盐对Oatp1a1介导的E3S摄取的抑制作用。1 mM的全氟丁酸盐和全氟戊酸盐没有明显抑制作用。在1 mM时观察到全氟己酸盐有抑制作用，并且随着链长增加至全氟癸酸盐，抑制水平升高。测定了链长在6至10之间的全氟羧酸盐的表观抑制常数（K（i,app））值。K（i,app）的对数值与链长呈负线性关系，与雄性大鼠中全氟羧酸盐的总清除率对数值呈正线性关系。这种体外与体内的相关性有力地支持了Oatp1a1在大鼠肾脏消除全氟羧酸盐中的肾小管重吸收作用。由于Oatp1a1在大鼠肾脏中的表达存在性别依赖性，因此Oatp1a1介导的肾小管重吸收被认为是大鼠中PFO性别依赖性肾脏消除的机制。
