Kinetics of lipopolysaccharide clearance by Kupffer and parenchyma cells in perfused rat liver

We studied the kinetics of [³H]lipopolysaccharide ([³H]LPS) (endotoxin) binding to Kupffer cells and hepatocytes at the level of the microtubular system after treatment with gadolinium chloride (GdCl₃) and colchicine. Liver perfusion in Sprague-Dawley rats involves both portal vein and thoracic inferior vena cava cannulations as inlet and outlet, respectively. The subhepatic inferior vena cava is ligated to prevent perfusate leakage. Buffer containing 2% serum and [³H]LPS is administered at 1 ml/min and collected for 50 min. Rate constants for hepatocellular clearance of [³H]LPS in controls, colchicine-treated rats, GdCl₃-treated rats, and colchicine plus GdCl₃-treated rats are assessed using a simplified mathematical model. Forward-binding, reversal-binding, residency time, and influx rate constants are estimated. Results show that in GdCl₃-treated rats, the hepatocytes effectively clear endotoxin from the circulation, and its ultimate binding affinity at the hepatocyte site is somewhat reduced compared to the Kupffer cells. In colchicine-treated rats, the disruption of the microtubule network altered [³H]LPS binding with Kupffer cells, suggesting that the microfilament-microtubular network also affects Kupffer cell function. Simultaneous treatments with colchicine and GdCl₃ increased the influx rate constant, suggesting that the compiled morphological alterations up-regulated endotoxin clearance by the liver, as indicated by a drastic increase in cellular vacuolation. In conclusion, the kinetics of the trafficking process of [³H]LPS clearance are regulated by apical-sinusoidal endocytotic and canalicular routes.