The effects of ethanol on the kinetics of toluene in the perfused rat liver.

In the isolated perfused rat liver as a metabolizing system, ethanol (17.1 mM) added directly to the perfusion medium decreased the extraction ratio of toluene (concentration range 0.2-16.4 microM) by 17-33%. The Michaelis-Menten constant, Km, was calculated to 3.9 microM and the maximum elimination rate, Vmax, to 10.8 and 11.4 nmol/min/g in the absence and presence of ethanol, respectively. The results indicate that the inhibitory effect of ethanol on the elimination of toluene is competitive. In a physiologically operating system, it must be taken into account that the elimination of toluene, apart from being influenced by the hepatic blood flow, may also be affected by lowered enzyme capacity for the metabolism of toluene.