Document Detail

The role of free radicals in paraquat-induced corneal lesions.
MedLine Citation:
PMID:  7647920     Owner:  NLM     Status:  MEDLINE    
Paraquat is a synthetic bipyridylium salt widely used as herbicide and defoliant. Enzyme-catalyzed redoxcycling of paraquat generates oxygen radicals. The toxic, even lethal, effects of paraquat are due to free radical-mediated tissue injury. Ocular lesions, sometimes quite severe, have been observed following accidental splashing of paraquat solutions onto the eyes. These studies were designed to document the generation of paraquat free radicals in corneal tissue, and to describe the histological nature of the corneal injuries in experimental animals (rabbits and monkeys). The EPR spectrum of rabbit corneas, 30 min. after intrastromal injection of paraquat, showed the signal of the free radical of paraquat. Ultrastructural studies of corneas 8 days after intrastromal injections (100 microliters) of paraquat solutions showed that the initial lesions occur at the epithelium/basement membrane interface. In rabbit cornea, dose dependent lesions were observed, i.e. whereas 50 mM paraquat caused only minimal damage to the epithelial basement membrane, 75 mM caused complete dissolution to the basement membrane with some damage to stromal collagen, and loss of epithelium with stromal ulceration and severe inflammatory response were observed with 150 mM paraquat. Monkey corneas were less susceptible than those of rabbits to the effects of paraquat. No lesions were observed following intrastromal injections of 50 mM or 75 mM paraquat. With higher concentrations of paraquat (100 mM and 150 mM) the primary injuries were to the proximal and lateral plasma membranes of basal epithelial cells; basement membrane alterations were detected only adjacent to areas of significant plasma membrane damage. The underlying Bowman's membrane and stroma were not affected. Anatomical differences between the corneas of rabbit and monkeys as well as possible biochemical differences may account for the species differences observed.
R E Nordquist; H Nguyen; J L Poyer; R Carubelli
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Free radical research     Volume:  23     ISSN:  1071-5762     ISO Abbreviation:  Free Radic. Res.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1995-09-26     Completed Date:  1995-09-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9423872     Medline TA:  Free Radic Res     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  61-71     Citation Subset:  IM    
Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA.
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MeSH Terms
Aotus trivirgatus
Corneal Diseases / chemically induced*,  pathology
Free Radicals*
Paraquat / toxicity*
Grant Support
Reg. No./Substance:
0/Free Radicals; 4685-14-7/Paraquat
Erratum In:
Free Radic Res 1995 Nov;23(5):513

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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