title: Effects of oxygen deficiency and calcium omission on carbon tetrachloride hepatotoxicity in isolated perfused livers from phenobarbital-pretreated rats.
abstract: The effect of oxygen concentration and Ca2+ omission on CCl4-induced hepatotoxicity was studied in a non-recirculating and hemoglobin-free liver perfusion system using phenobarbital-pretreated rats. With 95% O2-saturated perfusate, infusion of 0.5 mM CCl4 caused an instantaneous increase of thiobarbituric acid reactive substances (TBA-RS) in the effluent perfusate, accompanied by only a slight leakage of K+ and lactate dehydrogenase (LDH). CBrCl3 produced a far greater increase in the TBA-RS level, but again with slight K+ and LDH leakage. With 20% O2-saturated perfusate, CCl4 caused a marked LDH leakage, which was preceded by an early and considerable increase in K+ leakage coupled with Na+ uptake, Ca2+ uptake was initially slight, being enhanced concurrently with the LDH leakage. The TBA-RS level changed biphasically with an initial moderate and a succeeding greater increase coupled with LDH leakage. N,N"-Diphenyl-p-phenylenediamine and promethazine suppressed the TBA-RS production, but improved neither K+ nor LDH leakage. Omission of the Ca2+ from the perfusate reduced the initial K+ leakage as well as the later TBA-RS release, and markedly delayed the LDH leakage. In retrograde perfusion under low oxygen supply with Ca2+, CCl4 produced essentially the same toxic manifestations as those observed in the anterograde perfusion. Hepatocytes of the periportal and pericentral areas were not stained with trypan blue in the antero- and retrograde perfusion systems respectively. Thus, oxygen deficiency, rather than lipid peroxidation by itself, and the essential role of extracellular Ca2+ may be important for CCl4-induced hepatic cell necrosis, in which plasma membrane permeability change may be an early and critical event.
authors.affiliation: Division of Toxicology, Niigata College of Pharmacy, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Masuda
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002251:Carbon Tetrachloride / Q000378:metabolism / Q000633:toxicity*; D002252:Carbon Tetrachloride Poisoning / Q000378:metabolism*; D056486:Chemical and Drug Induced Liver Injury; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008107:Liver Diseases / Q000378:metabolism / Q000473:pathology; D008297:Male; D010100:Oxygen / Q000008:administration & dosage / Q000378:metabolism*; D010477:Perfusion / Q000379:methods; D010634:Phenobarbital / Q000494:pharmacology*; D010655:Phenylenediamines / Q000494:pharmacology; D011398:Promethazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D010655:Phenylenediamines; D002251:Carbon Tetrachloride; C004845:N,N'-diphenyl-4-phenylenediamine; D011398:Promethazine; D010100:Oxygen; D002118:Calcium; D010634:Phenobarbital