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

NCT01785511 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 12

Last updated 2013-02-20

No results posted yet for this study

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.

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.

Conditions

Interventions

RADIATION

UVA Radiation

UVA radiation exposure for 20 minutes

Sponsors & Collaborators

  • University of Edinburgh

    lead OTHER

Principal Investigators

  • Ninian Lang, MbChB · University of Edinburgh

Study Design

Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Max Age
45 Years
Sex
MALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2012-03-31
Primary Completion
2012-08-31
Completion
2012-08-31

Countries

  • United Kingdom

Study Locations

More Related Trials

Entities

Diseases

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT01785511 on ClinicalTrials.gov