title: Nitric oxide concentration increases in the cutaneous interstitial space during heat stress in humans.
abstract: To examine the role of nitric oxide (NO) in cutaneous active vasodilation, we measured the NO concentration from skin before and during whole body heat stress in nine healthy subjects. A forearm site was instrumented with a NO-selective, amperometric electrode and an adjacent intradermal microdialysis probe. Skin blood flow (SkBF) was monitored by laser-Doppler flowmetry (LDF). NO concentrations and LDF were measured in normothermia and heat stress. After heat stress, a solution of ACh was perfused through the microdialysis probe to pharmacologically generate NO and verify the electrode's function. During whole body warming, both SkBF and NO concentrations began to increase at the same internal temperature. Both SkBF and NO concentrations increased during heat stress (402 +/- 76% change from LDF baseline, P < 0.05; 22 +/- 5% change from NO baseline, P < 0.05). During a second baseline condition after heat stress, ACh perfusion led to increases in both SkBF and NO concentrations (496 +/- 119% change from LDF baseline, P < 0.05; 16 +/- 10% change from NO baseline, P < 0.05). We conclude that NO does increase in skin during heat stress in humans, attendant to active vasodilation. This result suggests that NO has a role beyond that of a permissive factor in the process; rather, NO may well be an effector of cutaneous vasodilation during heat stress.
authors.affiliation: Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, San Antonio, Texas 78229, USA. kelloggd@uthscsa.edu
authors.forename: D L
authors.initials: DL
authors.lastname: Kellogg
authors.forename: J L
authors.initials: JL
authors.lastname: Zhao
authors.forename: C
authors.initials: C
authors.lastname: Friel
authors.forename: L J
authors.initials: LJ
authors.lastname: Roman
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology; D004566:Electrodes; D005260:Female; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D017551:Microdialysis; D009569:Nitric Oxide / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply / Q000378:metabolism* / Q000503:physiopathology*; D014664:Vasodilation / Q000502:physiology
chemical_list: D009569:Nitric Oxide