Biological Reactive Intermediates IV pp 763-766 | Cite as
Covalent Binding of Oxidative Biotransformation Reactive Intermediates to Protein Influences Halothane-Associated Hepatotoxicity in Guinea Pigs
Abstract
Halothane (CF3CBrClH; H) biotransformation by cyt P-450 produces reactive intermediates along both oxidative (acyl chloride) and reductive (free radical) pathways that ultimately generate the metabolites trifluoroacetic acid and F−, respectively. Inhibiting oxidative metabolism with deuterated halothane (d-H) reduces resultant injury in our guinea pig model of acute H hepatotoxicity. To elucidate whether covalent binding of rective intermediates to proteins (oxidative pathway) or lipids (reductive pathway) is a mechanism of necrosis, male outbred Hartley guinea pigs (600–725 g), N=8, were exposed to either 1% (v/v) H or d-H at either 40% or 10% O2 for 4 hr. One-half of the animals were killed immediately after exposure for binding studies; the remainder at 96 hr post for evaluation of hepatotoxicity. Covalent binding of halothane intermediates to liver protein or lipid was determined by measuring the fluoride content of the bound moieties. The use of d-H and/or 10% O2 during exposure led to 63–88% reductions (p < 0.01) in plasma trifluoroacetic acid concentrations (H-40% O2 = 546; 73 mM, N=8) which were accompanied by 33–60% decreases (p <0.01) in binding to liver proteins (H-40% O2 = 1.36; 0.26 nmoles bound F−/mg protein, N=4), 78–84% decreases (p < 0.05) in 48 hr plasma ALT levels (H-40% O2 = 308; 219, control = 23 + 3, N=4) and a total amelioration of centilobular necrosis. Deuteration of H did not alter plasma F−concentrations or binding to lipid (H-40% O2 = 6.7; 1.9 M F−, N=8 and 5.6;1.8 nmoles bound F−/mg lipid phosphate, N=4). Exposure to H or d-H under 10% O2 increased (p < 0.05) plasma F− by almost 2 × and covalent binding to lipid by 5–6 × (p < 0.01) but ameliorated the centrilobular lesion. Covalent binding of oxidative pathway generated H reactive intermediates to protein is thus indicated as the mechanism of H-necrosis in guinea pigs.
Keywords
Covalent Binding Liver Protein Reductive Pathway Lipid Phosphate Centrilobular NecrosisPreview
Unable to display preview. Download preview PDF.
References
- DeGroot, H.E. and Noll, T. (1983). Halothane hepatotoxicity: Relation between metabolic activation, hypoxia, covalent binding, lipid peroxidation and liver cell damage. Hepatology 3, 601–606.Google Scholar
- Gandolfi, A.J., Sipes, I.G. and Brown, B.R. (1981). Detection of covalently bound halothane metabolites in the hypoxic rat model for halothane hepatotoxicity. Fund. App1. Toxicol. 1, 255–259.CrossRefGoogle Scholar
- Kenna, J.G., Satoh, H., Christ, D.D. and Pohl, L.R. (1987). Metabolic basis for a drug hypersensitivity: Antibodies in sera from patients with halothane hepatitis recognize liver neoantigens that contain the trifluoroacetyl group derived from halothane. J. Pharmacol. Exp. Therap. 245, 1103–1109.Google Scholar
- Lind, R.C., Gandolfi, A.J. and Hall, P de la M. (1987). Halothane hepatotoxicity in guinea pigs. Anesth. Analg. 66, 222–228.CrossRefPubMedGoogle Scholar
- Lind, R.C., Gandolfi, A.J. and Hall, P de la M. (1989). The role of oxidative biotransformation of halothane in the guinea pig model of halothane-associated hepatotoxicity. Anesthesiology 70, 649–653.CrossRefPubMedGoogle Scholar
- Maiorino, R.M., Gandolfi, A.J. and Sipes, I.G. (1980). Gas chromatographic method for the halothane metabolites, trifluoroacetic acid and bromide in biological fluids. J. Anal. Toxicol. 4, 250–254.PubMedGoogle Scholar
- Satoh, H., Gillette, J.R., Takemura, T., Ferrans, V.J., Jelenich, S.E., Kenna, J.G., Neuberger, J. and Pohl, L.R. Investigation of the immunological basis of halothane-induced hepatotoxicity. In, Biological Reactive Intermediates III (Eds. Kocis, J.J., Jollow, D.J., Witmer, C.M., Nelson, J.O. and Snyder, R., pp. 657–673, Plenum Publishing Corp., New York, 1986.CrossRefGoogle Scholar