Application of the hepatocytes bioreactor to xenobiotic biotransformation.
This study deals with the application of the previously developed immobilized and perfused isolated hepatocytes as a cellular system for the study of representative phase I and phase II of biotransformation reactions. To illustrate phase I reactions, aminopyrine (0.17-4.25 mmol/l) and hexobarbital (0.2 mmol/l) were selected. For phase II reactions, glutathione transferase activity was evaluated by using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate (0.125-2.0 mmol/l). Formaldehyde, that was formed from aminopyrine, increased steadily in the perfusion medium with time. The perfused hepatocytes eliminated hexobarbital at a much higher rate than the hepatocytes in suspension. At several time points the amount of CDNB-glutathione conjugate formed per one million hepatocytes in the bioreactor was almost twice the amount formed by the hepatocytes in suspension. The present data illustrate the successful application of the hepatocyte bioreactor in phase I and phase II of xenobiotic metabolism and indicate that the cells were metabolically more active than the cells in suspension.