Nitric oxide and cutaneous active vasodilation during heat stress in humans

• Published in: Journal of applied physiology (1985) 1998-09, Vol.85 (3), p.824-829
• Main Authors: Kellogg, D. L., Jr, Crandall, C. G, Liu, Y, Charkoudian, N, Johnson, J. M
• Format: Article
• Language: English
• Subjects: Adult; Anatomy & physiology; Biological and medical sciences; Body Temperature Regulation - physiology; Circulatory system; Cold Temperature; Enzyme Inhibitors - pharmacology; Female; Fundamental and applied biological sciences. Psychology; Gases; Hemodynamics - drug effects; Hemodynamics - physiology; Hot Temperature - adverse effects; Humans; Laser-Doppler Flowmetry; Male; Microdialysis; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - physiology; Nitric Oxide Synthase - antagonists & inhibitors; Nitroprusside - pharmacology; Regional Blood Flow - drug effects; Skin - blood supply; Space life sciences; Temperature; Vasodilation - physiology; Vertebrates: skin, associated glands, phaneres, light organs, various exocrine glands (salt gland, uropygial gland...), adipose tissue, connective tissue
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.85.3.824

1  Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio 78284; Departments of 2  Physiology, 3  Medicine, and 4  Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, 78284; 5  Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, 75231; and 6  University of Texas Southwestern Medical Center, Dallas, Texas 75235 Whether nitric oxide (NO) is involved in cutaneous active vasodilation during hyperthermia in humans is unclear. We tested for a role of NO in this process during heat stress (water-perfused suits) in seven healthy subjects. Two forearm sites were instrumented with intradermal microdialysis probes. One site was perfused with the NO synthase inhibitor N G -nitro- L -arginine methyl ester ( L -NAME) dissolved in Ringer solution to abolish NO production. The other site was perfused with Ringer solution only. At those sites, skin blood flow (laser-Doppler flowmetry) and sweat rate were simultaneously and continuously monitored. Cutaneous vascular conductance, calculated from laser-Doppler flowmetry and mean arterial pressure, was normalized to maximal levels as achieved by perfusion with the NO donor nitroprusside through the microdialysis probes. Under normothermic conditions, L -NAME did not significantly reduce cutaneous vascular conductance. During hyperthermia, with skin temperature held at 38-38.5°C, internal temperature rose from 36.66 ± 0.10 to 37.34 ± 0.06°C ( P