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

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
University of Edinburgh
ClinicalTrials.gov Identifier:
NCT01785511
First received: June 20, 2012
Last updated: February 19, 2013
Last verified: February 2013

June 20, 2012
February 19, 2013
March 2012
August 2012   (final data collection date for primary outcome measure)
Coronary Flow Reserve [ Time Frame: 0, 20, 40 and 60 mins ] [ Designated as safety issue: No ]
Change in coronary flow assessed pre and post UVA radiation versus control
Coronary Flow Reserve [ Time Frame: 0, 20, 40 and 60 mins ] [ Designated as safety issue: No ]
Coronary flow assessed pre and post UVA radiation versus control
Complete list of historical versions of study NCT01785511 on ClinicalTrials.gov Archive Site
  • Platelet Activation [ Time Frame: 0, 20, 40 and 60 mins ] [ Designated as safety issue: No ]
    Platelet activation assessed using platelet monocyte activity
  • Endogenous Fibrinolysis [ Time Frame: 0, 20, 40 and 60 minutes ] [ Designated as safety issue: No ]
    Assessed using flow cytometry
Same as current
Not Provided
Not Provided
 
Does Ultraviolet Irradiation Reduce Platelet Reactivity and Improve Coronary Microvascular Function in Man?
Does Ultraviolet Irradiation Reduce Platelet Reactivity and Improve Coronary Microvascular Function in Man?

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.

HYPOTHESES

  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.
Not Provided
Interventional
Not Provided
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Open Label
Primary Purpose: Basic Science
Hypertension
Radiation: UVA Radiation
UVA radiation exposure for 20 minutes
  • Sham Comparator: Sham UVA
    sham exposure will be provided by covering the UVA lamps with space blanket.
    Intervention: Radiation: UVA Radiation
  • Experimental: UVA Radiation
    Patients will be exposed to UVA radiation for 20 minutes
    Intervention: Radiation: UVA Radiation
Not Provided

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
12
August 2012
August 2012   (final data collection date for primary outcome measure)

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.
Male
18 Years to 45 Years
Yes
Contact information is only displayed when the study is recruiting subjects
United Kingdom
 
NCT01785511
UVA Study
Yes
University of Edinburgh
University of Edinburgh
Not Provided
Principal Investigator: Ninian Lang, MbChB University of Edinburgh
University of Edinburgh
February 2013

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP