Pretreatment with drinking water solutions containing trichloroethylene or chloroform enhances the hepatotoxicity of carbon tetrachloride in Fischer 344 rats.
Previous studies have demonstrated that various compounds, including the common groundwater contaminants trichloroethylene (TCE) and chloroform (CHCl3), can produce a synergistic toxic response when coadministered with the model hepatotoxicant carbon tetrachloride (CCl4). This phenomenon has not, however, been demonstrated following administration of these compounds in drinking water. Initial experiments indicated that Fischer 344 (F-344) rats were significantly more sensitive to these effects than the more commonly utilized Sprague-Dawley strain. To establish the suitability of this strain as a model, a variety of indicators of hepatotoxicity was evaluated and compared to histological evidence of injury 24 hr after dosing with CCl4 or a combination of CCl4 + TCE. Plasma alanine aminotransferase (ALT) activity was the most reliable indicator of hepatic injury and was well-correlated with the histologic data. Dose-response studies utilizing simultaneous ip dosing confirm the sensitivity of the F-344 rat, demonstrating synergistic toxicity at doses as low as 0.165 mmol/kg of CCl4 and 0.6 mmol/kg of TCE. Synergism was also detected following simultaneous ip administration of 1 mmol/kg CCl4 and 0.5 mmol/kg of CHCl3. To evaluate the effects of drinking water exposure, rats were pretreated for 3 days with solutions containing TCE (0-40 mM) or CHCl3 (0-8 mM) stabilized with 1% Emulphor (EL-620P) as their only source of fluids. A single, ip dose of CCl4 (1 mmol/kg) was then administered and 24 hr later animals were killed for examination of liver histology and determination of ALT activity. Although none of the pretreatments were detectably hepatoxic, rats which drank 15 and 40 mM TCE or 8 mM CHCl3 exhibited an enhanced response to CCl4.
Steup
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Department of Pharmacology and Toxicology, University of Arizona College of Pharmacy, Tucson 85721.
Wiersma
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McMillan
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Sipes
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D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D002252:Carbon Tetrachloride Poisoning / Q000097:blood / Q000503:physiopathology*; D056486:Chemical and Drug Induced Liver Injury / Q000097:blood / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011919:Rats, Inbred Strains; D013045:Species Specificity; D014241:Trichloroethylene / Q000008:administration & dosage / Q000633:toxicity*; D014881:Water Supply
D014241:Trichloroethylene; D000410:Alanine Transaminase