Liver slice uptake of intravenous and oral biliary contrast media

Using the liver slice technique, the uptake of five intravenous (including iodipamide, ioglycamide, iotroxamide, and iodoxamide) and one oral (iopodate) biliary contrast media into the rat liver was investigated. For all six compounds a saturable high-affinity and a nonsaturable low-affinity uptake system could be identified. There is no great difference of the liver uptake of the five intravenous compounds, but the oral compound iopodate is taken up by the rat liver to a much higher extent than the intravenous compounds. Since the liver slice uptake of the biliary contrast media was not clearly depending on metabolic energy, the presented results favor intracellular binding more than an active carrier as uptake mechanism. Human serum albumin strongly reduces hepatic uptake of all six compounds. The inhibition of the uptake was directly depending on the degree of serum albumin binding. No evidence for a carrier role of serum albumin within the uptake process could be found. The uptake mechanism of the liver for the biliary contrast media failed to be very specific, since liver slice uptake could be inhibited by iopanoate, bromosulfthalein, ouabain, and taurocholate and by each of the contrast media itself.