Alexis McMillen

Document Type

Honors Thesis


African-Americans have known impairments in vascular function as compared to their Caucasian counterparts. Dysfunction within the microvascular circulation, more specifically the cutaneous circulation, mirrors the systemic circulation and is indicative of risk for future cardiovascular disease. We aimed to test the hypothesis that acute pharmacological inhibition of superoxide can restore cutaneous microvascular responses to local heating. Healthy, college-aged males (African-Americans n=4, 23±2 years old; Caucasians n=4, 24±3 years old) were recruited from The University of Texas at Arlington. Prior to the infusion of drugs, each subject had baseline blood pressure and brachial artery flow mediated dilation (FMD) measurements. African-Americans had significantly higher baseline mean arterial pressure (P=0.038), but no significant difference in FMD (P=0.952). Each subject was equipped with four microdialysis fibers with each site containing either Tempol (superoxide scavenger), Apocynin (blunts oxidative stress from NADPH oxidase), Allopurinol (blunts oxidative stress from xanthine oxidase), or lactated Ringer solution (control). Each site was also equipped with local heating elements and laser Doppler probes to measure red blood cell flux, expressed as percent cutaneous vascular conductance (CVC) max. A two-way ANOVA (SigmaStat 3.11, Chicago, IL) with α=0.05 revealed significance in both CVC and nitric oxide contribution between the groups (P=0.008, P=<0.001 respectively). There was a significant difference between African-Americans and Caucasians at the site perfusing Ringers (P=0.002), but sites containing Tempol, Allopurinol, and Apocynin showed no significant difference. This suggests that reducing the circulating superoxide and superoxide production restores vascular responses in African-Americans, and supports the hypothesis that oxidative stress contributes to microvascular dysfunction seen in African-Americans.

Publication Date






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