TY - JOUR
T1 - Impaired sweating responses to a passive whole body heat stress in individuals with multiple sclerosis
AU - Allen, Dustin R.
AU - Huang, Mu
AU - Parupia, Iqra M.
AU - Dubelko, Ariana R.
AU - Frohman, Elliot
AU - Davis, Scott L.
N1 - Funding Information:
The considerable time and effort of the participants are greatly appreciated. This study was supported by National Heart, Lung, and Blood Institute Grant R15-HL-117224 (to S. L. Davis) and National Multiple Sclerosis Society Grants RG4043A1/1 and RG4696A3/2 (to S. L. Davis).
Publisher Copyright:
© 2017 the American Physiological Society.
PY - 2017
Y1 - 2017
N2 - Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS), disrupting autonomic function. The aim of this study was to test the hypothesis that individuals with MS have blunted control of thermoregulatory reflex increases in sweat rate (SR) and cutaneous vasodilation compared with controls during a passive whole body heat stress (WBH). Eighteen individuals with relapsing-remitting MS and 18 healthy controls (Con) participated in the study. Core temperature (Tcore), skin temperature, heart rate, arterial blood pressure (10-min intervals), skin blood flow (laser-Doppler flux, LDF), and SR were continuously measured during normothermic baseline (34°C water perfusing a tube-lined suit) and WBH (increased Tcore 0.8°C via 48°C water perfusing the suit). Following WBH, local heaters were warmed to 42°C, inducing peak cutaneous vasodilation at the site of LDF collection. Cutaneous vascular conductance (CVC) was calculated as the ratio of LDF to mean arterial pressure and expressed as a percentage of peak achieved during local heating. Individuals with MS had attenuated SR responses to WBH (∆SR from baseline: Con, 0.65 ± 0.27; MS, 0.42 ± 0.17 mg·cm-2·min-1, P = 0.003), whereas ∆%CVC42C from baseline was similar between groups (Con, 42 ± 16%; MS, 38 ± 12%, P = 0.39). SR responses were blunted as a function of Tcore in MS (interaction: group × Tcore, P = 0.03), of which differences were evident at ∆Tcore 0.7°C and 0.8°C (P < 0.05). No interaction was observed in ∆%CVC42C. Taken together, the findings show MS blunts sweating responses, whereas control of the cutaneous vasculature is preserved, in response to WBH. NEW & NOTEWORTHY This study is the first to assess the reflex control of the thermoregulatory system in individuals living with multiple sclerosis (MS). The novel findings are twofold. First, attenuated increases in sweat rate in subjects with MS compared with healthy controls were observed in response to a moderate increase (0.8°C) in core temperature via passive whole body heat stress. Second, it appears the reflex control of the cutaneous vasculature is preserved in MS.
AB - Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS), disrupting autonomic function. The aim of this study was to test the hypothesis that individuals with MS have blunted control of thermoregulatory reflex increases in sweat rate (SR) and cutaneous vasodilation compared with controls during a passive whole body heat stress (WBH). Eighteen individuals with relapsing-remitting MS and 18 healthy controls (Con) participated in the study. Core temperature (Tcore), skin temperature, heart rate, arterial blood pressure (10-min intervals), skin blood flow (laser-Doppler flux, LDF), and SR were continuously measured during normothermic baseline (34°C water perfusing a tube-lined suit) and WBH (increased Tcore 0.8°C via 48°C water perfusing the suit). Following WBH, local heaters were warmed to 42°C, inducing peak cutaneous vasodilation at the site of LDF collection. Cutaneous vascular conductance (CVC) was calculated as the ratio of LDF to mean arterial pressure and expressed as a percentage of peak achieved during local heating. Individuals with MS had attenuated SR responses to WBH (∆SR from baseline: Con, 0.65 ± 0.27; MS, 0.42 ± 0.17 mg·cm-2·min-1, P = 0.003), whereas ∆%CVC42C from baseline was similar between groups (Con, 42 ± 16%; MS, 38 ± 12%, P = 0.39). SR responses were blunted as a function of Tcore in MS (interaction: group × Tcore, P = 0.03), of which differences were evident at ∆Tcore 0.7°C and 0.8°C (P < 0.05). No interaction was observed in ∆%CVC42C. Taken together, the findings show MS blunts sweating responses, whereas control of the cutaneous vasculature is preserved, in response to WBH. NEW & NOTEWORTHY This study is the first to assess the reflex control of the thermoregulatory system in individuals living with multiple sclerosis (MS). The novel findings are twofold. First, attenuated increases in sweat rate in subjects with MS compared with healthy controls were observed in response to a moderate increase (0.8°C) in core temperature via passive whole body heat stress. Second, it appears the reflex control of the cutaneous vasculature is preserved in MS.
KW - Autonomic dysfunction
KW - Cutaneous vascular conductance
KW - Skin blood flow
KW - Sweat rate
KW - Thermoregulation
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U2 - 10.1152/jn.00897.2016
DO - 10.1152/jn.00897.2016
M3 - Article
C2 - 28275061
AN - SCOPUS:85021695695
SN - 0022-3077
VL - 118
SP - 7
EP - 14
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 1
ER -