Covalent binding of ¹⁴c-1,1,2-trichloroethane to hepatic proteins following acetone pretreatment

We have recently reported that pretreatment of rats with acetone potentiates both the hepatic glutathione (GSH) depletion and subsequent hepatotoxicity caused by 1,1,2-trichloroethane (TCEA). To determine if acetone treatment enhances the bioactivation of TCEA, the covalent binding of ¹⁴C-TCEA to tissue proteins was assessed both in vivo and in vitro. Male, Sprague-Dawley rats were treated with acetone (0.5 ml/kg; po), fasted 16 hr prior to dosing with ¹⁴C-TCEA (1.2 mmole/kg; ip), and killed 4 hr later. Overnight fasting, alone resulted in a six fold increase in covalent binding of ¹⁴C-TCEA to hepatic proteins compared to non-fasted rats. Acetone pretreatment, however, did not cause an increase in binding of ¹⁴C-TCEA 4 hr after dosing compared to fasted controls, although it did produce a 30% further decrease in hepatic GSH. When microsomes from acetone treated rats were incubated with ¹⁴C-TCEA, covalent binding to protein was significantly increased (35% over using, microsomes from fasted control rats. The covalent binding of ¹⁴C-TCEA to microsomal protein was inhibited 80% by the addition of GSH (1 mM). The data suggest that potentiation of TCEA hepatotoxicity by acetone may result in part, from alterations of TCEA bioactivation and hepatic GSH concentrations.