Covalent interaction of reactive metabolites with cytosolic coenzyme A as mechanism of haloethylene-induced acetonemia.

Previous experiments have shown that a number of xenobiotics such as halogenated ethylenes cause an experimental acetonemia. In addition, under exposure of rats to vinylidene fluoride (one of the agents producing this effect), the urinary excretion rates of acetoacetate and 3-hydroxybutyrate are enhanced. The enhanced formation of ketone bodies is theoretically explained by a covalent interaction of reactive metabolites of the applied xenobiotic with hepatic cytosolic coenzyme A. This theory is further corroborated by the following experiments: Microsomal incubations of [14C]vinyl chloride and [3H]coenzyme A lead to one metabolite containing 2 moles vinyl chloride/mole coenzyme A and two other with equimolar ratios of both components. Exposure of rats to vinyl chloride leads to a progressive depletion of hepatic cytosolic CoASH, but not of CoASH in mitochondria. In the cytosol acetyl-CoA is also diminished after vinyl chloride exposure. These changes may cause secondary effects in lipid metabolism which are regarded as responsible for the enhancement of ketone bodies.