Zonation of hepatic bile salt transporters.

Pericentral and periportal hepatocytes differ in their capacity to eliminate and velocity of eliminating bile acids and other organic anions. We wonder whether differences in the distribution of anion transporters (ntcp [M77479], besp [NM_031760], mrp2 [NM_012833], oatp1 [NM_017111], oatp2 [NM_131906]) cause the differences in bile acid excretion. Therefore, we analyzed the distribution of these anion transporters in periportal and pericentral cells by immunohistology, their mRNA by quantitative PCR, and regulating nuclear factors (NF-kappaB, HNF1, HNF3, HNF4, FXR, PXR) by gel shift assay. We did not find any differences in nuclear factors or regarding the proteins that could explain the zonal differences in anion transport.