A model for the multi-organ metabolism and nephrotoxicity of chlorotrifluoroethylene

Persistent Link:
http://hdl.handle.net/10150/288818
Title:
A model for the multi-organ metabolism and nephrotoxicity of chlorotrifluoroethylene
Author:
Hasal, Steven John, 1965-
Issue Date:
1998
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
During the past decade precision-cut tissue slices have begun to be utilized for toxicity and metabolism studies. These studies have primarily involved a single organ type. In this study, a new preparation of rat renal cortical slices was validated and used to investigate the toxicity of chlorotrifluoroethylene and its cysteine and glutathione conjugates. An additional level of complexity was added by utilizing a sequential incubation system in which rat renal cortical slices were directly incubated in the medium from liver slice incubations. Once the new renal slice preparation and sequential incubation system had been validated, these new methods were used to study the mechanism of toxicity of chlorotrifluoroethylene and it metabolites. The hypothesis being tested in these studies is that sequential biotransformation in the liver and the kidney is required for CTFE nephrotoxicity. In these studies I developed a sequential incubation system with precision-cut rat liver slices as the drug activating system and renal cortical slices as the target tissue for toxicity. Utilizing the sequential incubation system, I found that first incubating liver slices with CTFE and then transferring kidney slices to this liver slice incubation medium causes toxicity in the kidney slices. I also found that this toxicity correlates well with the toxicity observed with kidney slice incubations with the cysteine and glutathione conjugates of CTFE. By incubating slices with inhibitors of the various enzymes in the proposed metabolic pathway of CTFE, it was determined that glutathione conjugation in the liver and subsequent degradation by gamma-glutamyltranspeptidase are important steps in toxicity of CTFE. Although previous research with inhibitors of β-lyase have indicated that β-lyase is an essential enzyme in the bioactivation of CTFE, inhibition of the pyridoxal phosphate cofactor of this enzyme in renal slices did not reduce the toxicity of conjugates of CTFE. There was no reduction in toxicity when dipeptidases were inhibited when transport via the organic anion transporter or neutral amino acid transporter were inhibited. These data indicate that the glutathione conjugate of CTFE is formed in the liver and that the subsequent metabolism of this glutathione conjugate in the kidney is required for nephrotoxicity.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Health Sciences, Toxicology.; Health Sciences, Pharmacology.; Biology, Animal Physiology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Pharmacology and Toxicology
Degree Grantor:
University of Arizona
Advisor:
Brendel, Klaus

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleA model for the multi-organ metabolism and nephrotoxicity of chlorotrifluoroethyleneen_US
dc.creatorHasal, Steven John, 1965-en_US
dc.contributor.authorHasal, Steven John, 1965-en_US
dc.date.issued1998en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractDuring the past decade precision-cut tissue slices have begun to be utilized for toxicity and metabolism studies. These studies have primarily involved a single organ type. In this study, a new preparation of rat renal cortical slices was validated and used to investigate the toxicity of chlorotrifluoroethylene and its cysteine and glutathione conjugates. An additional level of complexity was added by utilizing a sequential incubation system in which rat renal cortical slices were directly incubated in the medium from liver slice incubations. Once the new renal slice preparation and sequential incubation system had been validated, these new methods were used to study the mechanism of toxicity of chlorotrifluoroethylene and it metabolites. The hypothesis being tested in these studies is that sequential biotransformation in the liver and the kidney is required for CTFE nephrotoxicity. In these studies I developed a sequential incubation system with precision-cut rat liver slices as the drug activating system and renal cortical slices as the target tissue for toxicity. Utilizing the sequential incubation system, I found that first incubating liver slices with CTFE and then transferring kidney slices to this liver slice incubation medium causes toxicity in the kidney slices. I also found that this toxicity correlates well with the toxicity observed with kidney slice incubations with the cysteine and glutathione conjugates of CTFE. By incubating slices with inhibitors of the various enzymes in the proposed metabolic pathway of CTFE, it was determined that glutathione conjugation in the liver and subsequent degradation by gamma-glutamyltranspeptidase are important steps in toxicity of CTFE. Although previous research with inhibitors of β-lyase have indicated that β-lyase is an essential enzyme in the bioactivation of CTFE, inhibition of the pyridoxal phosphate cofactor of this enzyme in renal slices did not reduce the toxicity of conjugates of CTFE. There was no reduction in toxicity when dipeptidases were inhibited when transport via the organic anion transporter or neutral amino acid transporter were inhibited. These data indicate that the glutathione conjugate of CTFE is formed in the liver and that the subsequent metabolism of this glutathione conjugate in the kidney is required for nephrotoxicity.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectHealth Sciences, Toxicology.en_US
dc.subjectHealth Sciences, Pharmacology.en_US
dc.subjectBiology, Animal Physiology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePharmacology and Toxicologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBrendel, Klausen_US
dc.identifier.proquest9829397en_US
dc.identifier.bibrecord.b38563459en_US
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