title: The effect of ethnicity on the vascular responses to cold exposure of the extremities.
abstract: OBJECTIVE
  Cold injuries are more prevalent in individuals of African descent (AFD). Therefore, we investigated the effect of extremity cooling on skin blood flow (SkBF) and temperature (T sk) between ethnic groups.
  
  
  METHODS
  Thirty males [10 Caucasian (CAU), 10 Asian (ASN), 10 AFD] undertook three tests in 30 °C air whilst digit T sk and SkBF were measured: (i) vasomotor threshold (VT) test--arm immersed in 35 °C water progressively cooled to 10 °C and rewarmed to 35 °C to identify vasoconstriction and vasodilatation; (ii) cold-induced vasodilatation (CIVD) test--hand immersed in 8 °C water for 30 min followed by spontaneous warming; (iii) cold sensitivity (CS) test--foot immersed in 15 °C water for 2 min followed by spontaneous warming. Cold sensory thresholds of the forearm and finger were also assessed.
  
  
  RESULTS
  In the VT test, vasoconstriction and vasodilatation occurred at a warmer finger T sk in AFD during cooling [21.2 (4.4) vs. 17.0 (3.1) °C, P = 0.034] and warming [22.0 (7.9) vs. 12.1 (4.1) °C, P = 0.002] compared with CAU. In the CIVD test, average SkBF during immersion was greater in CAU [42 (24) %] than ASN [25 (8) %, P = 0.036] and AFD [24 (13) %, P = 0.023]. Following immersion, SkBF was higher and rewarming faster in CAU [3.2 (0.4) °C min(-1)] compared with AFD [2.5 (0.7) °C min(-1), P = 0.037], but neither group differed from ASN [3.0 (0.6) °C min(-1)]. Responses to the CS test and cold sensory thresholds were similar between groups.
  
  
  CONCLUSIONS
  AFD experienced a more intense protracted finger vasoconstriction than CAU during hand immersion, whilst ASN experienced an intermediate response. This greater sensitivity to cold may explain why AFD are more susceptible to cold injuries.
authors: Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK, matthew.maley@port.ac.uk.
authors: Matthew J
authors: MJ
authors: Maley
authors: Clare M
authors: CM
authors: Eglin
authors: James R
authors: JR
authors: House
authors: Michael J
authors: MJ
authors: Tipton
mesh_terms: D044466:Asian People; D044383:Black People; D003080:Cold Temperature / Q000009:adverse effects*; D005385:Fingers / Q000098:blood supply / Q000294:innervation / Q000502:physiology*; D005627:Frostbite / Q000208:ethnology*; D006801:Humans; D007101:Immersion; D008297:Male; D012867:Skin / Q000098:blood supply / Q000294:innervation; D012881:Skin Temperature; D014661:Vasoconstriction; D014664:Vasodilation; D014666:Vasomotor System / Q000502:physiology; D014867:Water; D044465:White People; D055815:Young Adult
chemical_list: D014867:Water