Document Detail

Effect of nos inhibition on retinal arterial and capillary circulation in early arterial hypertension.
MedLine Citation:
PMID:  16603964     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Arterial hypertension is involved in the pathogenesis of end organ damage by influencing the ability of the vascular endothelium to produce nitric oxide (NO). This study analyzes changes of retinal and systemic NO-dependent circulation parameters by inhibiting nitric oxide synthase (NOS) in both hypertensive and normotensive individuals.
METHODS: In a double-blind crossover trial, 19 hypertensive patients (H, age 28.2 +/- 0.9 years) and 19 normotensive controls (N, age 26.9 +/- 0.9 years) were randomized treated either with candesartan or placebo. Both retinal capillary flow (RCF) and mean blood flow velocity of the central retinal artery (VCRA) were registered before and after NOS inhibition with N-monomethyl-L-arginine (L-NMMA, 3 mg/kg). In a subpopulation mean arterial pressure (MAP), cardiac output (CO), and the total peripheral resistance (TPR) were determined simultaneously.
RESULTS: Changes from baseline: In normotensive and hypertensive subjects infusion of L-NMMA led to an increase of MAP (N, +13.3 +/- 1.8%, P < 0.01; H, +14.3 +/- 2.4%, P < 0.01) and TPR (N, +36.9 +/- 3.8%, P < 0.01; H, +45.0 +/- 4.5%, P < 0.01), and to a decrease of CO (N, -21.1 +/- 1.5%, P < 0.01; H, -24.6 +/- 2.3%, P < 0.01). The L-NMMA effect on VCRA and RCF differed between controls and hypertensives. VCRA changed by + 17.3 +/- 6.2% (P < 0.05) and RCF by -7.3 +/- 3.0% (P < 0.05) in controls. In hypertensive subjects corresponding results were + 9.5 +/- 5.2% (P = NS) and + 2.7 +/- 3.8% (P = NS), respectively. The decrease of RCF due to L-NMMA was reduced in hypertension as compared to controls (P < 0.05). The calculated cross-sectional area of CRA was reduced by -58.7% in controls and increased by + 31.1% in hypertensive subjects. There was no significant correlation between the flow in the systemic and retinal circulation.
CONCLUSION: Only normotensives L-NMMA induces an acceleration of VCRA due to a probable vasoconstriction of the central retinal artery and despite of a reduced RCF. Already in early hypertension the NOS-dependent vascular tone in retinal arteries and capillaries is impaired. The regulation of the retinal capillary flow appeared to be independent from systemic circulation.
Georg Michelson; Simone Wärntges; Joana Harazny; Sebastian Oehmer; Christian Delles; Roland E Schmieder
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Retina (Philadelphia, Pa.)     Volume:  26     ISSN:  0275-004X     ISO Abbreviation:  Retina (Philadelphia, Pa.)     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-04-10     Completed Date:  2006-06-19     Revised Date:  2013-05-28    
Medline Journal Info:
Nlm Unique ID:  8309919     Medline TA:  Retina     Country:  United States    
Other Details:
Languages:  eng     Pagination:  437-44     Citation Subset:  IM    
Augenklinik mit Poliklinik, Universität Erlangen-Nürnberg, Schwabachanlage 6, D-91053 Erlangen, Germany.
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MeSH Terms
Angiotensin II Type 1 Receptor Blockers / therapeutic use
Angiotensin Receptor Antagonists
Benzimidazoles / therapeutic use
Biphenyl Compounds / therapeutic use
Blood Circulation
Blood Flow Velocity / physiology
Blood Pressure
Capillaries / physiology
Cardiac Output
Cross-Over Studies
Double-Blind Method
Enzyme Inhibitors / administration & dosage
Hypertension / drug therapy,  physiopathology*
Infusions, Intravenous
Nitric Oxide Synthase / antagonists & inhibitors*
Retinal Artery / physiology*
Tetrazoles / therapeutic use
omega-N-Methylarginine / administration & dosage
Reg. No./Substance:
0/Angiotensin II Type 1 Receptor Blockers; 0/Angiotensin Receptor Antagonists; 0/Benzimidazoles; 0/Biphenyl Compounds; 0/Enzyme Inhibitors; 0/Tetrazoles; 17035-90-4/omega-N-Methylarginine; EC Oxide Synthase; R85M2X0D68/candesartan cilexetil

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

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