VENA-CAVA PERFUSION IN-SITU - A TOOL FOR UPTAKE STUDIES

While studying the uptake of trypsin and thrombin by the perfused rat liver, we verified that these proteins are internalized neither by hep atocytes nor Kupffer cells. These results raised the possibility that the enzymes might be binding to endothelial cells, either hepatic or v ascular. In order to find out if the binding of enzymes to endothelial surface is a liver cell-specific phenomenon, we devised a system to p erfuse the rat inferior cava vein in situ. After exsanguination, the v ein was perfused with the recirculation of 30 mL of Krebs/BSA solution propellered by a pulsatile flow pump (10 mL/min). The liver was not e xsanguinated, but to assure that the organ was indeed excluded from th e circuit during the experiment at the end of the perfusion time we ad ded China ink in the perfusion fluid. We verified that trypsin is extr acted from the perfusion fluid by the vena cava as efficiently as by t he liver, suggesting that the most of the infused trypsin is removed m ainly by vascular endothelial cells when the liver perfusion model is used. On the other hand, thrombin is removed mainly by the liver cells since the uptake by the vena cava was insignificant. (C) 1997 Elsevie r Science Inc.