title: Investigating the roles of core and local temperature on forearm skin blood flow.
abstract: We sought to isolate the contributions of core and local temperature on forearm skin blood flow (SkBF), and to examine the interaction between local- and reflexive-mechanisms of SkBF control. Forearm SkBF was assessed using laser-Doppler flowmetry in eight males and eight females during normothermia and hyperthermia (+1.2°C rectal temperature). Mean experimental forearm temperature was manipulated in four, 5min blocks between neutral (A: 33.0°C) and warm (B: 38.5°C) in an A-B-A-B fashion during normothermia, and B-A-B-A during hyperthermia. Mean control forearm skin temperature was maintained at ~33°C. Finally, local heating to 44°C was performed on both forearms to elicit maximal SkBF. Data are presented as a percentage of maximal cutaneous vascular conductance (CVC), calculated as laser-Doppler flux divided by mean arterial pressure. No sex differences were observed in any CVC measures (P>0.05). During normothermia, increasing experimental forearm temperature to 38.5°C elevated CVC by 42±8%max (d=3.1, P<0.001). Subsequently decreasing experimental forearm temperature back down to 33.0°C reduced CVC by 36±7%max (d=2.5, P<0.001). Finally, the second increase in experimental forearm temperature to 38.5°C increased CVC by 25±6%max (d=1.9, P<0.0001). During hyperthermia, decreasing experimental forearm temperature to 33.0°C reduced CVC by 6±1%max (d=0.5, P<0.001). Increasing experimental forearm temperature to 38.5°C increased CVC by 4±2%max (d=0.4, P<0.001). Finally, decreasing experimental forearm temperature to 33.0°C reduced CVC by 8±2%max (d=0.7, P<0.001). Compared to normothermia, CVC responses to local temperature changes during hyperthermia were almost abolished (normothermia: d=1.9-3.1; hyperthermia: d=0.4-0.7). These data indicate that local temperature drives SkBF during normothermia, while reflexive mechanisms regulate SkBF during hyperthermia.
authors.affiliation: Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Mallette
authors.affiliation: Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Hodges
authors.affiliation: Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: McGarr
authors.affiliation: Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Gabriel
authors.affiliation: Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada. Electronic address: scheung@brocku.ca.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Cheung
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001833:Body Temperature Regulation; D005260:Female; D005334:Fever / Q000503:physiopathology*; D005542:Forearm; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D012018:Reflex; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D013997:Time Factors; D014664:Vasodilation; D014666:Vasomotor System / Q000503:physiopathology*; D055815:Young Adult
keywords: Cutaneous circulation; Local control; Reflexive vasodilatation; Thermal balance; Thermoregulation