title: Sex- and limb-specific differences in the nitric oxide-dependent cutaneous vasodilation in response to local heating.
abstract: Local heating of the skin is commonly used to assess cutaneous microvasculature function. Controversy exists as to whether there are limb or sex differences in the nitric oxide (NO)-dependent contribution to this vasodilation, as well as the NO synthase (NOS) isoform mediating the responses. We tested the hypotheses that 1) NO-dependent vasodilation would be greater in the calf compared with the forearm; 2) total NO-dependent dilation would not be different between sexes within limb; and 3) women would exhibit greater neuronal NOS (nNOS)-dependent vasodilation in the calf. Two microdialysis fibers were placed in the skin of the ventral forearm and the calf of 19 (10 male and 9 female) young (23 ± 1 yr) adults for the local delivery of Ringer solution (control) or 5 mM N(ω)-propyl-l-arginine (NPLA; nNOS inhibition). Vasodilation was induced by local heating (42°C) at each site, after which 20 mM N(G)-nitro-l-arginine methyl ester (l-NAME) was perfused for within-site assessment of NO-dependent vasodilation. Cutaneous vascular conductance (CVC) was calculated as laser-Doppler flux/mean arterial pressure and normalized to maximum (28 mM sodium nitroprusside, 43°C). Total NO-dependent vasodilation in the calf was lower compared with the forearm in both sexes (Ringer: 42 ± 5 vs. 62 ± 4%; P < 0.05; NPLA: 37 ± 3 vs. 59 ± 5%; P < 0.05) and total NO-dependent vasodilation was lower in the forearm for women (Ringer: 52 ± 6 vs. 71 ± 4%; P < 0.05; NPLA: 47 ± 6 vs. 68 ± 5%; P < 0.05). NPLA did not affect total or NO-dependent vasodilation across limbs in either sex (P > 0.05). These data suggest that the NO-dependent component of local heating-induced cutaneous vasodilation is lower in the calf compared with the forearm. Contrary to our original hypothesis, there was no contribution of nNOS to NO-dependent vasodilation in either limb during local heating.
authors.affiliation: Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Stanhewicz
authors.affiliation: Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Jody L
authors.initials: JL
authors.lastname: Greaney
authors.affiliation: Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: W Larry
authors.initials: WL
authors.lastname: Kenney
authors.affiliation: Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania lma191@psu.edu.
authors.forename: Lacy M
authors.initials: LM
authors.lastname: Alexander
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D005260:Female; D005542:Forearm / Q000098:blood supply; D006361:Heating / Q000009:adverse effects*; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D012039:Regional Blood Flow / Q000187:drug effects*; D012727:Sex Characteristics; D012867:Skin / Q000098:blood supply; D012879:Skin Physiological Phenomena / Q000187:drug effects; D014664:Vasodilation / Q000502:physiology*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology; D055815:Young Adult
chemical_list: D014665:Vasodilator Agents; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase
keywords: microdialysis; nitric oxide synthase; skin blood flow
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