The formation and biotransformation of cysteine conjugates of halogenated ethylenes by rabbit renal tubules |
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Authors: | C.D. Hassall A.J. Gandolfi R.C. Duhamel K. Brendel |
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Affiliation: | 1. Department of Pharmacology Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85724 U.S.A.;2. Department of Anesthesiology Arizona Health Sciences Center, University of Arizona, Tucson, AZ 85724 U.S.A. |
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Abstract: | The nephrotoxicity of chlorotrifluoroethylene (CTFE) was examined using isolated rabbit renal tubules suspensions. Exposure of the tubules to CTFE resulted in consumption of CTFE, formation of a glutathione conjugate and inhibition of active organic acid transport. Synthetic cysteine, N-acetylcysteine or glutathione conjugates of CTFE inhibited transport indicating S-conjugation as a possible toxic pathway. 1,2-dichlorovinyl glutathione (DCVG), a model synthetic glutathione conjugate, was used to examine the degradation and toxicity of these conjugates. DCVG inhibited rabbit renal tubule transport in vivo and in vitro. The DCVG was found to be degraded with the evolution of glutamine and glycine to produce the ultimate nephrotoxicant, dichlorovinyl cysteine. Dichlorovinyl cysteine is then bioactivated with the release of ammonia. This sequential degradation explains the latency of DCVG-induced renal transport inhibition relative to dichlorovinyl cysteine. It is now evident that certain halogenated ethylenes are capable of being biotransformed to glutathione conjugates in the kidney with their subsequent hydrolysis to nephrotoxic cysteine conjugates. |
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Keywords: | Nephrotoxins Dichlorovinyl cysteine Chlorotrifluoroethylene Renal tubule suspensions Active organic acid base transport CTFC CTFE chlorotrifluoroethylene CTFG CTF-NAC DCVC DCVG DCV-NAC NP-SA non-protein sulfhydryl PAH paraamino hippuric acid TAM trifluoroacetylated-methyl ester derivatives TEA tetraethylammonium bromide |
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