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Preserved Tolerance to Lower‐Body Negative Pressure during Heat Stress in Individuals with Multiple Sclerosis
Author(s) -
Huang Mu,
Allen Dustin R,
Keller David M,
Fadel Paul J,
Frohman Elliot M,
Davis Scott L
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1018.11
Subject(s) - presyncope , lower body , medicine , heat stress , multiple sclerosis , cardiology , endocrinology , blood pressure , heart rate , zoology , biology , psychiatry
Multiple sclerosis (MS), a progressive neurological disease, can result in impairments in both the autonomic control of cardiovascular and thermoregulatory function. We tested the following hypotheses: (i) patients with MS (n=10) would exhibit diminished tolerance to a simulated hemorrhagic challenge compared to age, height, body weight, and sex matched healthy controls (CON, n=10) in normothermic, baseline conditions (NT, perfusing 34 °C water via tube‐lined suit) and (ii) this diminished tolerance would be exaggerated during a passive whole‐body heat stress (WBH, increased core temperature by 0.8 °C perfusing 48 °C water). Hemorrhage was simulated via progressive lower‐body negative pressure (LBNP) to presyncope and tolerance was quantified via a cumulative stress index (CSI). During NT, no differences were observed between MS and CON in response to LBNP (MS: 534±303, CON: 622±209 CSI; p=0.46). However, attenuated CSI reductions (% decline from NT) were revealed during WBH in MS compared to CON (MS: 29.9±23.4, CON: 58.6±21.8 % decline; p=0.01) suggesting a reduced impact of heat stress on LBNP tolerance in MS patients. One possible explanation for these findings is preserved fluid volume, as whole body sweat loss was lower in MS compared to CON (MS: 0.9±0.4, CON: 1.5±0.6 % body mass deficit; p=0.05). Contrary to our original hypotheses, these preliminary findings suggest LBNP tolerance was not different between groups at NT baseline and that individuals with MS had less of a decline in LBNP tolerance during WBH. Support or Funding Information Supported by NIH (R15HL11722401) and NMSS (RG4696A3/2) grants.