OPPT_Perchloroethylene (Perc)_F. Human Health

Project ID

2571

Category

OPPT REs

Added on

March 8, 2017, 8:29 a.m.

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Journal Article

Abstract  Experimental data obtained in vivo with the closed-chamber gas uptake technique have been reported for a series of volatile chemicals. Pharmacokinetic analyses of these data have been performed either by using a two-compartment model or physiological models. In the former the transfer rate of chemical from ambient air to body is defined by the clearance of uptake. In the latter models the transfer rate depends on alveolar ventilation, cardiac output, and blood: air partition coefficient. In this communication we describe the quantitative relationship between clearance of uptake and alveolar ventilation, cardiac output, and blood: air partition coefficient. Theoretical values of clearance of uptake were calculated for a variety of volatile chemicals using literature data on alveolar ventilation, cardiac output, and blood: air partition coefficient. For most chemicals the experimentally determined values in rats and mice were about 60% of the theoretical values. This suggests that the inhalatory uptake rate of chemical may be overestimated if literature values of alveolar ventilation are used in physiological pharmacokinetic models for rodents.

Journal Article

Abstract  Trichloroethylene (TCE) and tetrachloroethylene (PCE) are structurally similar olefins that can cause liver and kidney toxicity. Adverse effects of these chemicals are associated with metabolism to oxidative and glutathione conjugation moieties. It is thought that CYP2E1 is crucial to the oxidative metabolism of TCE and PCE, and may also play a role in formation of nephrotoxic metabolites; however, inter-species and inter-individual differences in contribution of CYP2E1 to metabolism and toxicity are not well understood. Therefore, the role of CYP2E1 in metabolism and toxic effects of TCE and PCE was investigated using male and female wild-type [129S1/SvlmJ], Cyp2e1(-/-), and humanized Cyp2e1 [hCYP2E1] mice. To fill in existing gaps in our knowledge, we conducted a toxicokinetic study of TCE (600 mg/kg, single dose, i.g.) and a sub-acute study of PCE (500 mg/kg/d, 5 days, i.g.) in three strains. Liver and kidney tissues were subject to profiling of oxidative and glutathione conjugation metabolites of TCE and PCE, as well as toxicity endpoints. The amounts of TCA formed in the liver was hCYP2E1≈ 129S1/SvlmJ>Cyp2e1(-/-) for both TCE and PCE; levels in males were about 2-fold higher than in females. Interestingly, 2-3-fold higher levels of conjugation metabolites were observed in TCE-treated Cyp2e1(-/-) mice. PCE induced lipid accumulation only in liver of 129S1/SvlmJ mice. In the kidney, PCE exposure resulted in acute proximal tubule injury in both sexes in all strains (hCYP2E1≈129S1/SvlmJ>Cyp2e1(-/-)). In conclusion, our results demonstrate that CYP2E1 is an important, but not exclusive actor in the oxidative metabolism and toxicity of TCE and PCE.

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