Open AccessOptimization and Application of the Head Space Liver S9 Equilibration Technique for Metabolic Studies of Organic Solvents
Author(s) -
Mortensen Bjarte,
Nilsen Odd G.
Publication year - 1998
Publication title -
pharmacology & toxicology
Language(s) - English
Resource type - Journals
eISSN - 1600-0773
pISSN - 0901-9928
DOI - 10.1111/j.1600-0773.1998.tb01414.x
Subject(s) - acetone , styrene , chemistry , toluene , metabolism , mandelic acid , toxicokinetics , chromatography , styrene oxide , cyp1a2 , drug metabolism , benzene , cytochrome p450 , organic chemistry , biochemistry , copolymer , polymer
A head space liver S9 vial equilibration technique for qualitative and quantitative metabolism of volatile organic solvents in vitro is described and investigated for optimal experimental conditions with toluene and n ‐hexane as model substrates. The method was also used for studying the metabolic interaction between acetone and styrene. NADP + was a critical cofaclor in the system as concentrations above 2.5 mM resulted in inhibition of metabolism. Induction of cytochrome P450 by phenobarbital did not alter the observed cofactor dependency, and addition of vehicles such as rat blood did not enhance metabolism. Acetone‐induced liver S9 increased the primary oxidation of styrene and also the formation of styrene oxide, but not significantly that of mandelic acid. Acetone as such had no effect on the metabolic elimination of styrene, indicating that the interaction is mainly on the level of enzyme induction occurring after long‐term exposure to acetone. As earlier reports on styrene metabolism in vivo has not been able to detect styrene oxide in toxicokinetic studies with a sufficient degree of accuracy, the head space liver S9 vial equilibration technique may offer a fast and sensitive tool for screening of metabolic interactions between organic solvents when optimized for metabolic activity.