Healthy
Conditions
Keywords
BQ-123, Optic Nerve Head Blood Flow, Intraocular Pressure, Regional Blood Flow, Ocular Physiology, Optic Disk
Brief summary
Autoregulation is defined as the ability of a vascular bed to adapt its vascular resistance to changes in perfusion pressure. In the eye, several studies have reported that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. The investigators could recently show that Endothelin-1 is a key metabolite in the regulation of vascular tone in the eye and plays an important role in the blood flow autoregulation of the choroidal circulation. However, no data is yet available for the optic nerve head. Thus, the present study is designed to test the hypothesis that Endothelin-1 plays also a role in optic nerve head blood flow autoregulation. Therefore, subjects will perform squatting to increase systemic perfusion pressure during administration of either an endothelin A-receptor blocker (BQ-123) or placebo. Optic nerve head blood flow will be continuously measured during the procedure to investigate optic nerve head autoregulation.
Interventions
DRUGBQ-123
60 mcg/min, infusion period: 60 min
infusion period 60 minutes
DEVICELaser Doppler Flowmetry
blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flow
intraocular pressure measurements
OTHERsquatting
subjects will perform squatting for 6 minutes while blood flow measurements
Sponsors
Medical University of Vienna
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Men and women aged between 18 and 35 years, nonsmokers * Men and women will be included in equal parts * Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant * Normal findings in the laboratory testings unless the investigator considers an abnormality to be clinically irrelevant * 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 (except intake of oral contraceptives) * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * 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 * Pregnancy
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Optic nerve head pressure-flow relationship | 1 year |
Countries
Austria
Outcome results
None listed