Heterogeneity of ICG uptake and bile acid excretion within the hepatic lobule

Abstract

The contribution of periportal and pericentral hepatocytes to ICG uptake and bile acid excretion was studied in male Wistar rats using hemoglobin-free non-recirculating liver perfusion.
ICG (0.6mg/100g·BW) infused via portal vein was taken up by hepatocytes creating a decreasing concentration gradient from periportal to pericentral zone. While, retrograde (hepatic to portal) infusion of ICG created a "reverse" pericentral to periportal gradient. These findings suggest that the celular concentration gradients created by ICG are the consequence of the sequential extraction of ICG by zonal hepatocytes rather than that of different functions of zonal ones.
Taurocholate (0.8μmol/min/100g·BW) infused via portal vein enhanced the biliary excretion of ICG taken up by both periportal and pericentral hepatocytes. With the lower concentration of taurocholate (0.1μmol/min/100g·BW), the excretion of ICG taken up by periportal hepatocytes was stimulated, while ICG in pericentral zone was not affected. These results suggest that the heterogeneity of bile acid uptake and excretion exists and that under the physiological conditions, periportal hepatocytes are the most active in extracting and excreting bile acid than the remaining cells within the lobule.