East Tennessee State University Digital Commons @ East Tennessee State University Electronic Theses and Dissertations Student Works May 1987 Lung Paraquat Content and Effects on the Lung Glutathione Antioxidant System, Nadph, and Polyamines Resulting From Intravenous Coinfusion of Paraquat and Putrescine to Rats Jacob R. Dunbar East Tennessee State University Follow this and additional works at: https://dc.etsu.edu/etd Part of the Pharmacology Commons Recommended Citation Dunbar, Jacob R., "Lung Paraquat Content and Effects on the Lung Glutathione Antioxidant System, Nadph, and Polyamines Resulting From Intravenous Coinfusion of Paraquat and Putrescine to Rats" (1987). Electronic Theses and Dissertations. Paper 2669. https://dc.etsu.edu/etd/2669 This Dissertation - Open Access is brought to you for free and open access by the Student Works at Digital Commons @ East Tennessee State University. 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Other__________________________________________________________________________ University Microfilms International LUNG PARAQUAT CONTENT AND EFFECTS ON THE LUNG GLUTATHIONE ANTIOXIDANT SYSTEM, NADPH, AND POLYAMINES RESULTING FROM INTRAVENOUS COINFUSION OF PARAQUAT AND PUTRESCINE TO RATS A Dissertation Presented to the Faculty of the Department of Pharmacology Quillen-Dishner College of Medicine East Tennessee State University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy by Jacob R. Dunbar III May, 1987 APPROVAL This is to certify that the Graduate Committee of JACOB R. DUNBAR III met on the day of w £ z . The committee read and examined hia dissertation, supervised his defense of it in an oral examination, and decided to recommend that his study be submitted to the Graduate Council and the Associate Vice-President for Research and Graduate Studies in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomedical Science. Chat Committee Signed on behalf of . C * 4 p > the Graduate Council Associate Vice-President for Tteseesearch and Dean of the Graduate School ii ABSTRACT LUNG PARAQUAT CONTENT AND EFFECTS ON THE LUNG GLUTATHIONE ANTIOXIDANT SYSTEM, NADPH, AND FOLYAMINES RESULTING FROM INTRAVENOUS COINFUSION OF PARAQUAT AND PUTRESCINE TO RATS by Jacob R. Dunbar III Paraquat was administered to male, Sprague-Dawley rats via continoua infusion, at dosage rates of 250 (LoPQ) or 500 (HiPQ) nmoles/hr for seven days. The purpose was to characterise the effects of prolonged, low blood levels of the herbicide on selected lung biochemical parameters. The efficacy of putrescine as an inhibitor of pulmonary paraquat accumulation, in vivo, was assessed in these animals by I.V. coinfusion of 2500 or 5000 nmoles putrescine/hr. Dose-dependent levels of both paraquat and putrescine were achieved by 18 hours and were maintained throughout the exposure period. Terminal lung paraquat content was also dose-dependent and up to 18-fold greater than corresponding blood levels, indicative of pulmonary accumulation of the herbicide. Despite relatively high putrescine dosage rates, resulting blood levels of this diamine were low and did not significantly alter terminal lung paraquat content. No evidence of paraquat toxicity was seen in LoPQ animals while frank toxicity was observed in the HiPQ animals beginning between the fourth and fifth day. Qualitative histopathological examination of the lungs revealed changes typical of paraquat toxicity (e.g., interstitial edema, increase in type II cells) resulting from HiPQ. Significant increases were found in levels of lung glutathione and activities of the GSH peroxidase system enzymes, glucose-6-phosphate dehydrogenase and GSSG reductase. These changes were probably the result of paraquat-induced oxidant stress and increased NADPH requirements. Elevations in lung putrescine, spermidine, and ornithine decarboxylase activity were detected in HiPQ animals only, and reflected the observed lung damage and/or resulting "proliferative" state of the tissue rather than a direct response to paraquat. As in the case of pulmonary oxygen toxicity, the increased levels of lung polyamines may serve to mediate a reparative response to paraquat-induced lung damage. The results demonstrate only a narrow difference between a paraquat dose which produces no apparent lung damage but stimulates components of the GSH peroxidase antioxidant system and one which causes characteristic, paraquat-induced lung damage. The experimental model employed here represents a useful means to study subtle, paraquat-induced biochemical and morphological alterations in lung by avoiding paraquat doses which rapidly produce lung damage or are directly toxic to extrapulmonary tissues. iii DEDICATION This work is dedicated to Deborah, Rebecca, and Sara. Their understanding, tolerance, patience, and sacrifice are what made it possible. Iv ACKNOWLEDGEMENTS I wish to express my appreciation to the members of my graduate committee: Dr. Kenneth E. Ferelew, Dr. Ernest A. Daigneault, Dr. Richard M. Kostrzewa, Dr. Michael D. Miyamoto, Dr. Anthony J. DeLucia, and Dr. Robert V. Acuff for their invaluable professional guidance, criticisms, and encouragement contributing to the successful conception, design, and completion of this project. I am especially grateful to them for the patience and understanding afforded me during my completion of the degree requirements while necessarily maintaining fulltime outside employment. 1 would also like to acknowledge Dr. Lester R. Bryant, past Chairman and Dr. Paul E. Stanton, current Chairman of the Department of Surgery for their enthusiastic support and encouragement of me in the pursuit of this endevour. A special note of thanks is extended to Ms. Martha "Julie" Read, Department of Surgery, for her expert assistance in preparation of lung sections for histological evaluation and to Dr. Edward R. Freidlander, Department of Pathology, for his professional assessment of pulmonary histopathology. v CONTENTS Page APPROVAL............................................................. ii ABSTRACT............................................................. iii DEDICATION........................................................... iv ACKNOWLEDGEMENTS..................................................... v LIST OF FIGURES...................................................... viii Chapter 1. INTRODUCTION................................................. I Literature Review................................... 1 Summary of Biochemical Mechanisms of Paraquat Toxicity. 1 Proposed Mechanism of Paraquat Uptake In Lung......... ■ 4 Importance of Putrescine and Other Polyamines in Paraquat Toxicity................................. 8 Effects of Paraquat in the Isolated, Perfused Rabbit Lung............................................