N-DEMETHYLATION OF AMINOPYRINE INVIVO AND IN THE ISOLATED HEPATOCYTE OF THE RAT

The N-demethylation of [dimethylamine-14C]aminopyrine was monitored in vivo and in isolated hepatocytes of the rat by collection of 14CO2, The isolated hepatocyte is capable of aminopyrine N-demethylation rates similar to those occurring in vivo. The kinetics of N-demethylation in the isolated cells indicate the presence of two separate reactions with Km values of 32 and 710 μM. The kinetics of N-demethylationin vivo, however, indicates the presence of one reaction with an intermediate Km value of 260 μM. It is thought that the two reactions observed in the hepatocytes also occur in vivo but that it is not possible to differentiate between them. © 1979.