ORCID Identifier(s)

0000-0002-1463-1335

Graduation Semester and Year

2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Kinesiology

Department

Kinesiology

First Advisor

Matthew R. Brothers

Abstract

Hypertension disproportionately affects the black population, contributing to a greater impact of cardiovascular disease in these individuals. While multiple factors underlie the development of hypertension in this population, impaired vascular function is routinely observed in this population beginning at a young age and is a likely an early contributor to the development of high blood pressure. However, the origins of this impairment have not been elucidated. Therefore, the current set of studies aimed to determine the extent to which oxidative stress plays a role in blunted vascular function in the black population. Studies 1 and 2 (Chapters 2 and 3) utilized intradermal microdialysis to mechanistically investigate the causes of blunted cutaneous microvascular function in this population. In Study 1, the enzymes NADPH oxidase and xanthine oxidase were identified as potential contributors to superoxide-mediated reductions in otherwise healthy, young black men, whereas they did not appear to play a significant role in the blunted local heating response observed in young black women. Study 2 aimed to test whether NADPH oxidase inhibition, xanthine oxidase inhibition, or tetrahydrobiopterin supplementation could augment blunted muscarinic-mediated cutaneous dilation in black men. While the findings of that study were somewhat inconclusive, our observation of potential phenotypic differences provides important rationale for future research. Lastly, Study 3 (Chapter 4) aimed to determine the acute peripheral vascular effects of an oral antioxidant cocktail on vascular function in young black men. Utilizing a randomized, double blinded design, reactive hyperemia and brachial artery flow mediated dilation (FMD) were assessed pre- and 120 min post- antioxidant and placebo treatments. Unexpectedly, vascular function was blunted at the post timepoint across both conditions, likely due to the sedentary nature of the protocol. FMD was paradoxically reduced to a greater extent in the antioxidant condition. The work described herein is an important initial step in determining the role of oxidative stress on vascular dysfunction in black individuals. Future research building upon these findings may ultimately result in therapies to lessen the disparate burden of hypertension on the black population.

Keywords

Vascular function, Oxidative stress, Xanthine oxidase, NADPH oxidase, Microvascular

Disciplines

Kinesiology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

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