The stimulation of murine hepatic aryl hydrocarbon hydroxylase activity in vitro by caffeine

The activity of aryl hydrocarbon hydroxylase (AHH) of murine liver is increased by caffeine. However, other analogs of caffeine, such as theophylline, theobromine xanthine, hypoxanthine and uric acid, do not significantly alter AHH activity. The maximal stimulation is observed at a caffeine concentration of approx. 3 mM. The Km of AHH for benzo[a]pyrene is decreased in the presence of caffeine. Thus, the inhibition by caffeine of the binding of polycyclic aromatic hydrocarbons (PAH) to DNA may be related to its effect on AHH.