title: Preserved reflex cutaneous vasodilation in cystic fibrosis does not include an enhanced nitric oxide-dependent mechanism.
abstract: In humans, vasoactive intestinal peptide (VIP) may play a role in reflex cutaneous vasodilation during body heating. We tested the hypothesis that the nitric oxide (NO)-dependent contribution to active vasodilation is enhanced in the skin of subjects with cystic fibrosis (CF), compensating for sparse levels of VIP. In 2 parallel protocols, microdialysis fibers were placed in the skin of 11 subjects with CF and 12 controls. Lactated Ringer was perfused at one microdialysis site and NG-nitro-L-arginine methyl ester (2.7 mg/ml) was perfused at a second microdialysis site. Skin blood flow was monitored over each site with laser-Doppler flowmetry. In protocol 1, local skin temperature was increased 0.5 degrees C every 5 s to 42 degrees C, and then it maintained at 42 degrees C for approximately 45 min. In protocol 2, subjects wore a tube-lined suit perfused with water at 50 degrees C, sufficient to increase oral temperature (Tor) 0.8 degrees C. Cutaneous vascular conductance (CVC) was calculated (flux/mean arterial pressure) and scaled as percent maximal CVC (sodium nitroprusside; 8.3 mg/ml). Vasodilation to local heating was similar between groups. The change (Delta%CVCmax) in CVC with NO synthase inhibition on the peak (9+/-3 vs. 12+/-5%CVCmax; P=0.6) and the plateau (45+/-3 vs. 35+/-5%CVCmax; P=0.1) phase of the skin blood flow response to local heating was similar in CF subjects and controls, respectively. Reflex cutaneous vasodilation increased CVC in CF subjects (58+/-4%CVCmax) and controls (53+/-4%CVCmax; P=0.37) and NO synthase inhibition attenuated CVC in subjects with CF (37+/-6%CVCmax) and controls (35+/-5%CVCmax; P=0.8) to a similar degree. Thus the preservation of cutaneous active vasodilation in subjects with CF is not associated with an enhanced NO-dependent vasodilation.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, 200 First St. SW., Rochester, MN 55905, USA. wilkins.brad@mayo.edu
authors.forename: Brad W
authors.initials: BW
authors.lastname: Wilkins
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Martin
authors.forename: Shelly K
authors.initials: SK
authors.lastname: Roberts
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001833:Body Temperature Regulation; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D012018:Reflex; D012867:Skin / Q000098:blood supply* / Q000294:innervation / Q000503:physiopathology*; D014664:Vasodilation
chemical_list: D009569:Nitric Oxide