Does eNOS Gene Polymorphism Play a Role in the Maintenance of Basal Vascular Tone in the Choroid or Optic Nerve Head?

Study Overview
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Brief Summary
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Nitric oxide (NO) is a potent endothelium-derived vasodilatator that plays a major role in the control of ocular blood flow. Endothelial NO synthase (eNOS) is one of three isoforms of NOS producing NO through hydroxylation of L-arginine. The eNOS gene is located on the long arm of chromosome 7, and different polymorphic variations have been identified. These single nucleotide polymorphisms (sNP´s) have the ability to change transcription activity and therefore enzyme levels. Recent data indicate that the T -786C polymorphism (especially the homozygous variant) is associated with reduced eNOS activity and consequently impaired NO production. In the present study the investigators want to investigate if the T -786C eNOS gene polymorphism determines choroidal and optic nerve head blood flow.

Official Title
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Does eNOS Gene Polymorphism Play a Role in the Maintenance of Basal Vascular Tone in the Choroid or Optic Nerve Head?

Conditions
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Ocular Physiology, Regional Blood Flow

Intervention / Treatment
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* Drug: NG-monomethyl-L-arginine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men aged between 19 and 35 years, nonsmokers Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant Homozygous variants of the T -786C genotyping (CC or TT) Normal ophthalmic findings, ametropia less than 3 diopters Exclusion Criteria: Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study Treatment in the previous 3 weeks with any drug Symptoms of a clinically relevant illness in the 3 weeks before the first study day History of hypersensitivity to the trial drug or to drugs with a similar chemical structure History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs Blood donation during the previous 3 weeks

Ages Eligible for Study
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Minimum Age: 19 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: 1<br>homozygous mutant: CC allele of the eNOS T-786C gene | Drug: NG-monomethyl-L-arginine<br>* intravenous administration, bolus over 5 minutes, dosage 6mg/kg<br>* Other names: L-NMMA;|
| Other: 2<br>homozygous mutant: TT allele of the eNOS T-786C gene | Drug: NG-monomethyl-L-arginine<br>* intravenous administration, bolus over 5 minutes, dosage 6mg/kg<br>* Other names: L-NMMA;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Genotyping |  | performed during the first year before measurements | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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eNOS Gene Polymorphism, ocular blood flow