The Effect of Antioxidants on Skin Blood Flow-BH4

Status Completed

Clinical Trial Summary

The goal of this study is to examine possible mechanisms of heightened vasoconstriction in Black/African American men and women as possible links to the elevated prevalence of cardiovascular dysfunction and disease. The main targets in this study are sources of oxidative stress

Clinical Trial Description

African Americans (AA) not only have a higher prevalence of hypertension but the severity of the cardiovascular complications related to this condition are greater in this population relative to other populations. While the underlying causes of this elevated risk are multifactorial, vascular dysfunction (i.e. impaired vasodilation and/or augmented vasoconstriction) is believed to be a key contributing factor. The investigators have recently observed (UTA IRB 2016-0268) that the small blood vessels in the skin (the cutaneous microvasculature) in AA, but otherwise healthy individuals, have an impaired blood flow response in the cutaneous circulation to local heating when compared to age, body mass index (BMI), and gender, matched Caucasians (CA). This blunted response is abolished in AA when the sites are pre-treated with either Allopurinol or Apocynin which block the production of xanthine oxidase and NADPH oxidase, respectively. In addition, Tetrahydrobiopterin (BH4) is critically involved in vascular function. BH4 is a cofactor involved in the conversion of L-Arginine into the potent vasodilator nitric oxide (NO) by the enzyme endothelial nitric oxide synthase (eNOS). Reduced bioavailable BH4 leads to elevated oxidative stress and thus impaired vascular function.

In addition to local heating another commonly utilized research approach to assess microcirculatory vascular function is via local infusion of the potent vasodilator methacholine (Mch). Mch is an acetylcholine analog that causes endothelial dependent vasodilation primarily through stimulation of NO production. Much like the local heating data mentioned above, our laboratory (data collected while at UT Austin) has demonstrated a blunted response to Mch in AA relative to CA. However, the role of xanthine oxidase, NADPH oxidase, and BH4 in this blunted response remains unknown. ;

Study Design

Related Conditions & MeSH terms

Clinical Trial Details

NCT number	NCT03680573
Study type	Interventional
Source	The University of Texas at Arlington
Contact
Status	Completed
Phase	Phase 1
Start date	January 8, 2018
Completion date	May 5, 2018

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Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.

Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.