Working… Menu

Does Ultraviolet Irradiation Reduce Platelet Reactivity and Improve Coronary Microvascular Function in Man?

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01785511
Recruitment Status : Completed
First Posted : February 7, 2013
Last Update Posted : February 20, 2013
Information provided by (Responsible Party):
University of Edinburgh

Brief Summary:

Endothelium derived nitric oxide (NO) regulates vascular tone and blood pressure in man. NO also inhibits platelet aggregation and mediates a variety of beneficial anti-inflammatory and repair mechanisms. NO may also be a mediator in the release of the endogenous fibrinolytic factor, tissue-plasminogen activating factor (t-PA) from the endothelium.1 Via these actions it plays a very important role in protection of the vasculature from atherothrombosis and clinical sequelae such as myocardial infarction and stroke.

Visible and ultraviolet (UV) light relax vascular smooth muscles by producing NO in a phenomenon known as photorelaxation.2 The investigators have demonstrated significant stores of pre-formed, bound NO and other nitrosospecies in human skin, which are rapidly released upon exposure to UVA.3 The investigators have demonstrated recently that serum nitrite and nitroso-species are increased after standing in a UVA phototherapy cabinet and that local UVA exposure is associated with increased forearm arterial blood flow that is independent of skin temperature. The investigators have also demonstrated a fall in mean arterial blood pressure in subjects exposed UVA.

Cardiovascular morbidity and the prevalence of hypertension vary with latitude. The investigators hypothesise that some of this geographical variation may be explained by a diminished sunlight/UVA exposure with attendant negative effects upon NO bio-availability.4 To further examine the potential beneficial effects of UVA exposure we will examine the effects of whole-body UVA upon platelet activation and upon myocardial/coronary arterial flow reserve. The investigators will correlate these measures with systemic nitrate, nitrite and nitroso-species content in healthy volunteers.


  1. UVA irradiation enhances coronary flow reserve in healthy volunteers.
  2. UVA irradiation suppresses platelet activation in healthy volunteers.
  3. UVA irradiation enhances the release of endogenous fibrinolytic factors in healthy volunteers.

Condition or disease Intervention/treatment Phase
Hypertension Radiation: UVA Radiation Not Applicable

Layout table for study information
Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 12 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Does Ultraviolet Irradiation Reduce Platelet Reactivity and Improve Coronary Microvascular Function in Man?
Study Start Date : March 2012
Actual Primary Completion Date : August 2012
Actual Study Completion Date : August 2012

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Sham Comparator: Sham UVA
sham exposure will be provided by covering the UVA lamps with space blanket.
Radiation: UVA Radiation
UVA radiation exposure for 20 minutes

Experimental: UVA Radiation
Patients will be exposed to UVA radiation for 20 minutes
Radiation: UVA Radiation
UVA radiation exposure for 20 minutes

Primary Outcome Measures :
  1. Coronary Flow Reserve [ Time Frame: 0, 20, 40 and 60 mins ]
    Change in coronary flow assessed pre and post UVA radiation versus control

Secondary Outcome Measures :
  1. Platelet Activation [ Time Frame: 0, 20, 40 and 60 mins ]
    Platelet activation assessed using platelet monocyte activity

  2. Endogenous Fibrinolysis [ Time Frame: 0, 20, 40 and 60 minutes ]
    Assessed using flow cytometry

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy male volunteers aged between 18-45 years (inclusive).

Exclusion Criteria:

  • Inability to provide informed consent
  • Co-existent systemic disease (including any history of asthma, reactive airways disease or hypertension)
  • Contraindication to UVA treatment
  • Any history of cardiac conduction abnormality (including bundle branch block or atrial fibrillation)
  • Smoker
  • Current intake of aspirin, other non-steroid anti-inflammatory medications or any regular medication.
  • Recent infective/inflammatory condition
  • Echocardiographic evidence of left ventricular hypertrophy (left ventricular septal diameter >1.2 cm in diastole), systolic dysfunction or significant valvular stenosis or regurgitation.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01785511

Layout table for location information
United Kingdom
University of Edinburgh
Edinburgh, Lothian, United Kingdom, Eh16 4SA
Sponsors and Collaborators
University of Edinburgh
Layout table for investigator information
Principal Investigator: Ninian Lang, MbChB University of Edinburgh

Layout table for additonal information
Responsible Party: University of Edinburgh Identifier: NCT01785511     History of Changes
Other Study ID Numbers: UVA Study
First Posted: February 7, 2013    Key Record Dates
Last Update Posted: February 20, 2013
Last Verified: February 2013
Keywords provided by University of Edinburgh:
UV radiation
coronary flow reserve
nitric oxide
Additional relevant MeSH terms:
Layout table for MeSH terms
Vascular Diseases
Cardiovascular Diseases