Role of Nitric Oxide in Optic Nerve Head Blood Flow Regulation During Isometric Exercise in Healthy Humans
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 18
- 试验地点
- 1
- 主要终点
- Optic nerve head pressure-flow relationship
研究概览
简要总结
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 recently showed that nitric oxide (NO) 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 NO 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 a nitric oxide synthase inhibitor (L-NMMA), an α-receptor agonist (phenylephrine) or placebo. Optic nerve head blood flow will be continuously measured during the procedure to investigate optic nerve head autoregulation.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Triple (Participant, Investigator, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 35 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •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
排除标准
- •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
研究组 & 干预措施
1
NG-monomethyl-L-arginine (L-NMMA)
干预措施: NG-monomethyl-L-arginine (L-NMMA) (Drug)
1
NG-monomethyl-L-arginine (L-NMMA)
干预措施: Laser Doppler Flowmetry (Device)
1
NG-monomethyl-L-arginine (L-NMMA)
干预措施: Goldmann applanation tonometer (Device)
1
NG-monomethyl-L-arginine (L-NMMA)
干预措施: squatting (Other)
2
Phenylephrine
干预措施: Phenylephrine (Drug)
2
Phenylephrine
干预措施: Laser Doppler Flowmetry (Device)
2
Phenylephrine
干预措施: Goldmann applanation tonometer (Device)
2
Phenylephrine
干预措施: squatting (Other)
3
Physiological saline solution
干预措施: Physiological saline solution (as placebo) (Drug)
3
Physiological saline solution
干预措施: Laser Doppler Flowmetry (Device)
3
Physiological saline solution
干预措施: Goldmann applanation tonometer (Device)
3
Physiological saline solution
干预措施: squatting (Other)
结局指标
主要结局
Optic nerve head pressure-flow relationship
时间窗: in total 6x on 3 study days
次要结局
未报告次要终点
研究者
Gerhard Garhofer
Assoc. Prof. PD Dr.
Medical University of Vienna