Orthostatic challenge does not alter skin sympathetic nerve activity in heat-stressed humans

Jian Cui, Thad E. Wilson, Craig G. Crandall

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Perturbations that load or unload baroreceptors do not alter skin sympathetic nerve activity (SSNA) in normothermic individuals. However, in pronounced heat-stressed individuals, when a significant component of the SSNA signal is sudomotor and possibly vasodilator in origin, the effects of baroreceptor unloading via an orthostatic stress on SSNA remain unclear. The purpose of the present study was to test the hypothesis that low and moderate levels of orthostatic stress via lower body negative pressure (LBNP) alter SSNA in pronounced heat-stressed individuals. In both normothermic and heat-stressed conditions, progressive LBNP at -3, -6, -9, -12, -15, -18, -21 and -40 mm Hg were applied to 11 subjects for 2 min per stage. Whole-body heating increased sublingual temperature by 0.7±0.1°C, heart rate by 28±2.1 bpm, SSNA by 259±76 %, forearm skin blood flow by 631±142% and forearm sweat rate to 0.68±0.14 mg/cm 2/min (all p<0.005), but did not change mean arterial blood pressure (MAP) (p>0.05). LBNP did not change total SSNA in normothermic or heat-stressed conditions (both p>0.05), although skin blood flow and sweat rate decreased during moderate levels of LBNP while heat stressed. These data suggest that in pronounced heat-stressed individuals, when a significant component of the SSNA signal contains sudomotor and possibly cutaneous active vasodilator activities, low and moderate levels of baroreceptor unloading via LBNP do not alter total SSNA. This observation, coupled with reductions in skin blood flow and sweating during moderate levels of LBNP, suggests that integrated SSNA should not be used as an indicator of baroreflex modulation of the cutaneous vasculature or sweat rate in heat-stressed subjects.

Original languageEnglish (US)
Pages (from-to)54-61
Number of pages8
JournalAutonomic Neuroscience: Basic and Clinical
Volume116
Issue number1-2
DOIs
StatePublished - Nov 30 2004

Fingerprint

Hot Temperature
Skin
Lower Body Negative Pressure
Pressoreceptors
Sweat
Vasodilator Agents
Forearm
Sweating
Baroreflex
Heating
Heart Rate
Temperature

All Science Journal Classification (ASJC) codes

  • Endocrine and Autonomic Systems
  • Clinical Neurology
  • Cellular and Molecular Neuroscience

Cite this

@article{b6c994f0f87648889aca33a7ac31e94d,
title = "Orthostatic challenge does not alter skin sympathetic nerve activity in heat-stressed humans",
abstract = "Perturbations that load or unload baroreceptors do not alter skin sympathetic nerve activity (SSNA) in normothermic individuals. However, in pronounced heat-stressed individuals, when a significant component of the SSNA signal is sudomotor and possibly vasodilator in origin, the effects of baroreceptor unloading via an orthostatic stress on SSNA remain unclear. The purpose of the present study was to test the hypothesis that low and moderate levels of orthostatic stress via lower body negative pressure (LBNP) alter SSNA in pronounced heat-stressed individuals. In both normothermic and heat-stressed conditions, progressive LBNP at -3, -6, -9, -12, -15, -18, -21 and -40 mm Hg were applied to 11 subjects for 2 min per stage. Whole-body heating increased sublingual temperature by 0.7±0.1°C, heart rate by 28±2.1 bpm, SSNA by 259±76 {\%}, forearm skin blood flow by 631±142{\%} and forearm sweat rate to 0.68±0.14 mg/cm 2/min (all p<0.005), but did not change mean arterial blood pressure (MAP) (p>0.05). LBNP did not change total SSNA in normothermic or heat-stressed conditions (both p>0.05), although skin blood flow and sweat rate decreased during moderate levels of LBNP while heat stressed. These data suggest that in pronounced heat-stressed individuals, when a significant component of the SSNA signal contains sudomotor and possibly cutaneous active vasodilator activities, low and moderate levels of baroreceptor unloading via LBNP do not alter total SSNA. This observation, coupled with reductions in skin blood flow and sweating during moderate levels of LBNP, suggests that integrated SSNA should not be used as an indicator of baroreflex modulation of the cutaneous vasculature or sweat rate in heat-stressed subjects.",
author = "Jian Cui and Wilson, {Thad E.} and Crandall, {Craig G.}",
year = "2004",
month = "11",
day = "30",
doi = "10.1016/j.autneu.2004.08.009",
language = "English (US)",
volume = "116",
pages = "54--61",
journal = "Autonomic Neuroscience: Basic and Clinical",
issn = "1566-0702",
publisher = "Elsevier",
number = "1-2",

}

Orthostatic challenge does not alter skin sympathetic nerve activity in heat-stressed humans. / Cui, Jian; Wilson, Thad E.; Crandall, Craig G.

In: Autonomic Neuroscience: Basic and Clinical, Vol. 116, No. 1-2, 30.11.2004, p. 54-61.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Orthostatic challenge does not alter skin sympathetic nerve activity in heat-stressed humans

AU - Cui, Jian

AU - Wilson, Thad E.

AU - Crandall, Craig G.

PY - 2004/11/30

Y1 - 2004/11/30

N2 - Perturbations that load or unload baroreceptors do not alter skin sympathetic nerve activity (SSNA) in normothermic individuals. However, in pronounced heat-stressed individuals, when a significant component of the SSNA signal is sudomotor and possibly vasodilator in origin, the effects of baroreceptor unloading via an orthostatic stress on SSNA remain unclear. The purpose of the present study was to test the hypothesis that low and moderate levels of orthostatic stress via lower body negative pressure (LBNP) alter SSNA in pronounced heat-stressed individuals. In both normothermic and heat-stressed conditions, progressive LBNP at -3, -6, -9, -12, -15, -18, -21 and -40 mm Hg were applied to 11 subjects for 2 min per stage. Whole-body heating increased sublingual temperature by 0.7±0.1°C, heart rate by 28±2.1 bpm, SSNA by 259±76 %, forearm skin blood flow by 631±142% and forearm sweat rate to 0.68±0.14 mg/cm 2/min (all p<0.005), but did not change mean arterial blood pressure (MAP) (p>0.05). LBNP did not change total SSNA in normothermic or heat-stressed conditions (both p>0.05), although skin blood flow and sweat rate decreased during moderate levels of LBNP while heat stressed. These data suggest that in pronounced heat-stressed individuals, when a significant component of the SSNA signal contains sudomotor and possibly cutaneous active vasodilator activities, low and moderate levels of baroreceptor unloading via LBNP do not alter total SSNA. This observation, coupled with reductions in skin blood flow and sweating during moderate levels of LBNP, suggests that integrated SSNA should not be used as an indicator of baroreflex modulation of the cutaneous vasculature or sweat rate in heat-stressed subjects.

AB - Perturbations that load or unload baroreceptors do not alter skin sympathetic nerve activity (SSNA) in normothermic individuals. However, in pronounced heat-stressed individuals, when a significant component of the SSNA signal is sudomotor and possibly vasodilator in origin, the effects of baroreceptor unloading via an orthostatic stress on SSNA remain unclear. The purpose of the present study was to test the hypothesis that low and moderate levels of orthostatic stress via lower body negative pressure (LBNP) alter SSNA in pronounced heat-stressed individuals. In both normothermic and heat-stressed conditions, progressive LBNP at -3, -6, -9, -12, -15, -18, -21 and -40 mm Hg were applied to 11 subjects for 2 min per stage. Whole-body heating increased sublingual temperature by 0.7±0.1°C, heart rate by 28±2.1 bpm, SSNA by 259±76 %, forearm skin blood flow by 631±142% and forearm sweat rate to 0.68±0.14 mg/cm 2/min (all p<0.005), but did not change mean arterial blood pressure (MAP) (p>0.05). LBNP did not change total SSNA in normothermic or heat-stressed conditions (both p>0.05), although skin blood flow and sweat rate decreased during moderate levels of LBNP while heat stressed. These data suggest that in pronounced heat-stressed individuals, when a significant component of the SSNA signal contains sudomotor and possibly cutaneous active vasodilator activities, low and moderate levels of baroreceptor unloading via LBNP do not alter total SSNA. This observation, coupled with reductions in skin blood flow and sweating during moderate levels of LBNP, suggests that integrated SSNA should not be used as an indicator of baroreflex modulation of the cutaneous vasculature or sweat rate in heat-stressed subjects.

UR - http://www.scopus.com/inward/record.url?scp=8844269473&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=8844269473&partnerID=8YFLogxK

U2 - 10.1016/j.autneu.2004.08.009

DO - 10.1016/j.autneu.2004.08.009

M3 - Article

C2 - 15556838

AN - SCOPUS:8844269473

VL - 116

SP - 54

EP - 61

JO - Autonomic Neuroscience: Basic and Clinical

JF - Autonomic Neuroscience: Basic and Clinical

SN - 1566-0702

IS - 1-2

ER -