Tempol augments the blunted cutaneous microvascular thermal reactivity in healthy young African Americans

• Published in: Experimental physiology 2018-03, Vol.103 (3), p.343-349
• Main Authors: Hurr, Chansol, Patik, Jordan C., Kim, KiYoung, Christmas, Kevin M., Brothers, R. Matthew
• Format: Article
• Language: English
• Subjects: Adult; African American; African Americans; Antioxidants; Ascorbic acid; Blood Flow Velocity - drug effects; Blood pressure; cardiovascular disease; Cardiovascular diseases; Conductance; Cyclic N-Oxides - pharmacology; Enzyme Inhibitors - pharmacology; Erythrocytes; Female; Humans; hypertension; Male; microcirculation; Microdialysis; Microvasculature; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitric Oxide Donors - therapeutic use; Nitric Oxide Synthase - antagonists & inhibitors; Nitroprusside - pharmacology; Oxidation; Oxidative stress; Oxidative Stress - drug effects; Regional Blood Flow - drug effects; Skin - blood supply; Sodium; Sodium nitroprusside; Spin Labels; Superoxide dismutase; Tempol; Vasodilation; Vasodilation - drug effects; Young Adult
• ISSN: 0958-0670; 1469-445X
• DOI: 10.1113/EP086776

New Findings What is the central question of this study? The purpose was to determine whether there is a difference between African Americans and Caucasians in cutaneous microvascular function and whether this difference is attributable to elevated oxidative stress. What is the main finding and its importance? The main finding is that African Americans have an attenuated cutaneous vasodilatation during local heating relative to Caucasians that is restored with local infusion of the superoxide dismutase mimetic, tempol. This suggests that superoxide mediates microvascular dysfunction and might contribute to the greater prevalence of cardiovascular disease in this population. African Americans (AA) have elevated risk for cardiovascular disease relative to other populations. We hypothesized that the cutaneous hyperaemic response to local heating is reduced in young AA relative to Caucasian Americans (CA) and that this is attributable to elevated oxidative stress. As such, ascorbic acid (a global antioxidant) and tempol (a superoxide dismutase mimetic) would improve this response in AA. Microdialysis fibres received lactated Ringer solution (control), 10 mm ascorbic acid or 10 μm 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (tempol) at a rate of 2.0 μl min−1. Cutaneous vascular conductance (CVC) was calculated as the red blood cell flux divided by mean arterial pressure. Data were presented as a percentage of maximal CVC (%CVCmax) induced by 44°C heating plus sodium nitroprusside. Twenty‐four (12 AA, 12 CA) young (23 ± 4 years old) subjects participated. During 39°C heating, the %CVCmax was lower in AA at the control (CA, 65 ± 20% versus AA, 47 ± 15%; P