Evaluation of changes in hepatic disposition of phenolsulfonphthalein, indocyanine green and fluorescein isothiocyanate-dextran at low temperatures using a rat liver perfusion system

Objectives The aim of this study was to determine the factor changing the hepatic disposition of a drug during hypothermia using a rat liver perfusion system. Methods The livers of male Wistar rats were perfused at 37, 32 or 28°C in the single‐pass mode. Venous outflow dilution patterns and biliary excretion rate patterns of phenolsulfonphthalein (PSP), indocyanine green (ICG) and fluorescein isothiocyanate (FITC)‐dextran (FD‐4, MW 4400) after the injection of a bolus into the perfused rat liver were analysed based on statistical moment theory. Key findings The first‐pass extraction ratio (E_h) of PSP was significantly decreased at 32 and 28°C compared with 37°C. The biliary recovery of PSP and its conjugate was decreased and the biliary excretion was kept at a high concentration and was prolonged by low perfusion temperatures. ICG was almost extracted by a single‐pass through the liver even at 32 and 28°C. The biliary recovery of ICG was significantly decreased at low temperature. Although the distribution volume of FD‐4 as a vascular reference was not changed by perfusion temperature, the E_h of FD‐4 was decreased at 28°C although not markedly. Conclusion The change in hepatic disposition of a drug at low perfusion temperatures differed according to disposition processes under hypothermia.