Document Detail

Real-time direct measurement of nitric oxide in bovine perfused eye trabecular meshwork using a clark-type electrode.
MedLine Citation:
PMID:  12964955     Owner:  NLM     Status:  MEDLINE    
NO was detected in bovine trabecular meshwork (TM). Bovine eyes were perfused (posterior ciliary artery). In some eyes (operated eyes) a NO electrode was inserted adjacent to the TM (scleral flap). Vascular perfusion/intraocular pressures (VPP/IOP) were recorded. In operated eyes, epinephrine (1 nM-100 microM) increased NO (maximally 979.9 +/- 117.6 nM, mean +/- SDM). Timolol (1 mM) shifted the epinephrine-NO concentration-response curve rightward (2.94 log units) without significantly changing the maximal response (903.0 +/- 67.7 nM, mean +/- SDM). The non-selective NO synthase (NOS) inhibitor L-NMMA (100 microM) virtually abolished the NO response to epinephrine. L-NMMA alone (1 microM-100 microM) significantly reduced tonic NO generation (maximally 109.5 +/- 24.9 nM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. In unoperated eyes, epinephrine (1 nM-100 microM) reduced IOP (maximally 2.56 +/- 0.64 mmHg, mean +/- SDM). Epinephrine (100 microM) mildly increased VPP (4.6 +/- 1.3 mmHg, mean +/- SDM). Baseline aqueous humor formation rate (11.5 +/- 3.2 microl/min, mean +/- SDM) was unaffected. Effluent perfusate (effusate) total NO(2)(-) was determined by enzymatically reducing all NO(3)(-) to NO(2)(-), then assessing resultant NO(2)(-) (Griess assay). Epinephrine (1 nM-1 microM) increased effusate NO(2)(-) (maximally 15.8 +/- 4.9 microM, mean +/- SDM). Timolol (1 mM) reduced, and L-NMMA (100 microM) virtually abolished effusate NO(2)(-) response to epinephrine. L-NMMA alone (1 microM-100 microM) reduced tonic effusate NO(2)(-) (maximally from 5.8 +/- 1.6 microM to 1.1 +/- 0.9 microM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. NO is generated tonically in bovine TM and increases in response to epinephrine.
J C Millar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics     Volume:  19     ISSN:  1080-7683     ISO Abbreviation:  J Ocul Pharmacol Ther     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-09-10     Completed Date:  2004-01-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9511091     Medline TA:  J Ocul Pharmacol Ther     Country:  United States    
Other Details:
Languages:  eng     Pagination:  299-313     Citation Subset:  IM    
Department of Biology & Health Science, Faculty of Science, Technology & Design, University of Luton, Park Square Campus, Luton, England.
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MeSH Terms
Aqueous Humor / drug effects,  metabolism
Dose-Response Relationship, Drug
Epinephrine / pharmacokinetics
Intraocular Pressure / drug effects
Nitric Oxide / analysis*,  biosynthesis,  metabolism
Nitric Oxide Synthase / pharmacokinetics
Nitrites / chemistry,  metabolism
Timolol / pharmacokinetics
Trabecular Meshwork / chemistry*,  drug effects*,  metabolism
omega-N-Methylarginine / pharmacokinetics
Reg. No./Substance:
0/Nitrites; 10102-43-9/Nitric Oxide; 17035-90-4/omega-N-Methylarginine; 26839-75-8/Timolol; 51-43-4/Epinephrine; EC Oxide Synthase

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