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Richey RE, Ruiz YI, Cope HL, Moore AM, Walsh MA, Garfield TC, Olivencia-Yurvati AH, Romero SA. Cyclooxygenase inhibition does not blunt thermal hyperemia in skeletal muscle of humans. J Appl Physiol (1985) 2024; 136:151-157. [PMID: 38059292 PMCID: PMC11191756 DOI: 10.1152/japplphysiol.00657.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/08/2023] Open
Abstract
Acute heat exposure increases skeletal muscle blood flow in humans. However, the mechanisms mediating this hyperemic response remain unknown. The cyclooxygenase pathway is active in skeletal muscle, is heat sensitive, and contributes to cutaneous thermal hyperemia in young healthy humans. Therefore, the purpose of this study was to test the hypothesis that cyclooxygenase inhibition would attenuate blood flow in the vastus lateralis muscle during localized heating. Twelve participants (6 women) were studied on two separate occasions: 1) time control (i.e., no ibuprofen); and 2) ingestion of 800 mg ibuprofen, a nonselective cyclooxygenase inhibitor. Experiments were randomized, counter-balanced, and separated by at least 10 days. Pulsed short-wave diathermy was used to induce unilateral deep heating of the vastus lateralis for 90 min, whereas the contralateral leg served as a thermoneutral control. Microdialysis was utilized to bypass the cutaneous circulation and directly measure local blood flow in the vastus lateralis muscle of each leg via the ethanol washout technique. Heat exposure increased muscle temperature and local blood flow (both P < 0.01 vs. baseline). However, the thermal hyperemic response did not differ between control and ibuprofen conditions (P ≥ 0.2). Muscle temperature slightly decreased for the thermoneutral leg (P < 0.01 vs. baseline), yet local blood flow remained relatively unchanged across time for control and ibuprofen conditions (both P ≥ 0.7). Taken together, our data suggest that inhibition of cyclooxygenase-derived vasodilator prostanoids does not blunt thermal hyperemia in skeletal muscle of young healthy humans.NEW & NOTEWORTHY Acute heat exposure increases skeletal muscle blood flow in humans. However, the mechanisms mediating this hyperemic response remain unknown. Using a pharmacological approach combined with microdialysis, we found that thermal hyperemia in the vastus lateralis muscle was well maintained despite the successful inhibition of cyclooxygenase. Our results suggest that cyclooxygenase-derived vasodilator prostanoids do not contribute to thermal hyperemia in skeletal muscle of young healthy humans.
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Affiliation(s)
- Rauchelle E Richey
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ysabella I Ruiz
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Heidi L Cope
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Amy M Moore
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Mackenzie A Walsh
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Tyson C Garfield
- Department of Internal Medicine and Geriatrics, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Albert H Olivencia-Yurvati
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
- Department of Surgery, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Steven A Romero
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Wee J, Tan XR, Gunther SH, Ihsan M, Leow MKS, Tan DSY, Eriksson JG, Lee JKW. Effects of Medications on Heat Loss Capacity in Chronic Disease Patients: Health Implications Amidst Global Warming. Pharmacol Rev 2023; 75:1140-1166. [PMID: 37328294 DOI: 10.1124/pharmrev.122.000782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/20/2023] [Accepted: 05/31/2023] [Indexed: 06/18/2023] Open
Abstract
Pharmacological agents used to treat or manage diseases can modify the level of heat strain experienced by chronically ill and elderly patients via different mechanistic pathways. Human thermoregulation is a crucial homeostatic process that maintains body temperature within a narrow range during heat stress through dry (i.e., increasing skin blood flow) and evaporative (i.e., sweating) heat loss, as well as active inhibition of thermogenesis, which is crucial to avoid overheating. Medications can independently and synergistically interact with aging and chronic disease to alter homeostatic responses to rising body temperature during heat stress. This review focuses on the physiologic changes, with specific emphasis on thermolytic processes, associated with medication use during heat stress. The review begins by providing readers with a background of the global chronic disease burden. Human thermoregulation and aging effects are then summarized to give an understanding of the unique physiologic changes faced by older adults. The effects of common chronic diseases on temperature regulation are outlined in the main sections. Physiologic impacts of common medications used to treat these diseases are reviewed in detail, with emphasis on the mechanisms by which these medications alter thermolysis during heat stress. The review concludes by providing perspectives on the need to understand the effects of medication use in hot environments, as well as a summary table of all clinical considerations and research needs of the medications included in this review. SIGNIFICANCE STATEMENT: Long-term medications modulate thermoregulatory function, resulting in excess physiological strain and predisposing patients to adverse health outcomes during prolonged exposures to extreme heat during rest and physical work (e.g., exercise). Understanding the medication-specific mechanisms of altered thermoregulation has importance in both clinical and research settings, paving the way for work toward refining current medication prescription recommendations and formulating mitigation strategies for adverse drug effects in the heat in chronically ill patients.
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Affiliation(s)
- Jericho Wee
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Xiang Ren Tan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Samuel H Gunther
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Mohammed Ihsan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Melvin Khee Shing Leow
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Doreen Su-Yin Tan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Johan G Eriksson
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Jason Kai Wei Lee
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
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Belity T, Horowitz M, Hoffman JR, Epstein Y, Bruchim Y, Todder D, Cohen H. Heat-Stress Preconditioning Attenuates Behavioral Responses to Psychological Stress: The Role of HSP-70 in Modulating Stress Responses. Int J Mol Sci 2022; 23:ijms23084129. [PMID: 35456946 PMCID: PMC9031159 DOI: 10.3390/ijms23084129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/28/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022] Open
Abstract
Exposure to high ambient temperature is a stressor that influences both biological and behavioral functions and has been previously shown to have an extensive impact on brain structure and function. Physiological, cellular and behavioral responses to heat-stress (HS) (40-41 °C, 2 h) were evaluated in adult male Sprague-Dawley rats. The effect of HS exposure before predator-scent stress (PSS) exposure (i.e., HS preconditioning) was examined. Finally, a possible mechanism of HS-preconditioning to PSS was investigated. Immunohistochemical analyses of chosen cellular markers were performed in the hippocampus and in the hypothalamic paraventricular nucleus (PVN). Plasma corticosterone levels were evaluated, and the behavioral assessment included the elevated plus-maze (EPM) and the acoustic startle response (ASR) paradigms. Endogenous levels of heat shock protein (HSP)-70 were manipulated using an amino acid (L-glutamine) and a pharmacological agent (Doxazosin). A single exposure to an acute HS resulted in decreased body mass (BM), increased body temperature and increased corticosterone levels. Additionally, extensive cellular, but not behavioral changes were noted. HS-preconditioning provided behavioral resiliency to anxiety-like behavior associated with PSS, possibly through the induction of HSP-70. Targeting of HSP-70 is an attractive strategy for stress-related psychopathology treatment.
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Affiliation(s)
- Tal Belity
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel;
| | - Michal Horowitz
- Laboratory of Environmental Physiology, Faculty of Dental Medicine, The Hebrew University, Jerusalem 9112102, Israel; (M.H.); (Y.B.)
| | - Jay R. Hoffman
- Department of Physical Therapy, Ariel University, Ariel 40700, Israel;
| | - Yoram Epstein
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv and the Heller Institute of Medical Research, Sheba Medical Center, Ramat Gan 52621, Israel;
| | - Yaron Bruchim
- Laboratory of Environmental Physiology, Faculty of Dental Medicine, The Hebrew University, Jerusalem 9112102, Israel; (M.H.); (Y.B.)
- Intensive Care, Veterinary Emergency and Specialist Center, Youth Village Ben Shemen, Ben-Shemen 7311200, Israel
| | - Doron Todder
- Beer-Sheva Mental Health Center, Ministry of Health, Anxiety and Stress Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8461144, Israel;
| | - Hagit Cohen
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel;
- Beer-Sheva Mental Health Center, Ministry of Health, Anxiety and Stress Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8461144, Israel;
- Correspondence: ; Tel.: +972-8-6401743
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Emerson DM, Chen SCL, Kelly MR, Parnell B, Torres-McGehee TM. Non-steroidal anti-inflammatory drugs on core body temperature during exercise: A systematic review. J Exerc Sci Fit 2021; 19:127-133. [PMID: 33552178 PMCID: PMC7829260 DOI: 10.1016/j.jesf.2020.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Because of their anti-pyretic effects, some individuals prophylactically use non-steroidal anti-inflammatory drugs (NSAIDs) to blunt core temperature (Tc) increases during exercise, thus, potentially improving performance by preventing hyperthermia and/or exertional heat illness. However, NSAIDs induce gastrointestinal damage, alter renal function, and decrease cardiovascular function, which could compromise thermoregulation and increase Tc. The aim of this systematic review was to evaluate the effects of NSAIDs on Tc in exercising, adult humans. METHODS We conducted searches in MEDLINE, PubMed, Cochrane Reviews, and Google Scholar for literature published up to November 2020. We conducted a quality assessment review using the Physiotherapy Evidence Database scale. Nine articles achieved a score ≥ seven to be included in the review. RESULTS Seven studies found aspirin, ibuprofen, and naproxen had no effect (p > .05) on Tc during walking, running, or cycling for ≤ 90 min in moderate to hot environments. Two studies found significant Tc changes. In one investigation, 81 mg of aspirin for 7-10 days prior to exercise significantly increased Tc during cycling (p < .001); final Tc at the end of exercise = 38.3 ± 0.1 °C vs. control = 38.1 ± 0.1 °C. In contrast, participants administered 50 mg rofecoxib for 6 days experienced significantly lower Tc during 45 min of cycling compared to placebo (NSAID Tc range ≈ 36.7-37.2 °C vs control ≈ 37.3-37.8 °C, p < 0.05). CONCLUSIONS There are limited quality studies examining NSAID effects on Tc during exercise in humans. The majority suggest taking non-selective NSAIDs (e.g., aspirin) 1-14 days before exercise does not significantly affect Tc during exercise. However, it remains unclear whether Tc increases, decreases, or does not change during exercise with other NSAID drug types (e.g., naproxen), higher dosages, chronic use, greater exercise intensity, and/or greater environmental temperatures.
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Affiliation(s)
- Dawn M. Emerson
- Department of Health, Sport, and Exercise Sciences, University of Kansas, KS, 66045, USA
| | - Stephen CL. Chen
- Division of Exercise and Sport Science, Bob Jones University, SC, 29614, USA
| | - Melani R. Kelly
- Department of Health, Sport, and Exercise Sciences, University of Kansas, KS, 66045, USA
| | - Bryant Parnell
- Department of Exercise Science, University of South Carolina, SC, 29208, USA
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Muia CM, McGarr GW, Schmidt MD, Fujii N, Amano T, Kenny GP. Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black-African and Caucasian descent during exercise in the heat. Exp Physiol 2019; 104:1762-1768. [PMID: 31609035 DOI: 10.1113/ep088115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/11/2019] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Nitric oxide modulates cutaneous vasodilatation and sweating during exercise-induced heat stress in young men. However, it remains uncertain whether these effects are reduced in black-African descendants, who commonly demonstrate reduced nitric oxide bioavailability. Therefore, we assessed whether black-African descendants display reduced nitric oxide-dependent cutaneous vasodilatation and sweating compared with Caucasians in these conditions. What is the main finding and its importance? Nitric oxide-dependent cutaneous vasodilatation and sweating were similar between groups, indicating that reduced nitric oxide bioavailability in black-African descendants does not attenuate these heat-loss responses during an exercise-induced heat stress. ABSTRACT Men of black-African descent are at an increased risk of heat-related illness relative to their Caucasian counterparts. This might be attributable, in part, to reduced cutaneous nitric oxide (NO) bioavailability in this population, which might alter local cutaneous vasodilatation and sweating. To evaluate this, we compared these heat-loss responses in young men (18-30 years of age) of black-African (n = 10) and Caucasian (n = 10) descent during rest, exercise and recovery in the heat. Participants were matched for physical characteristics and fitness, and they were all born and raised in the same temperate environment (i.e. Canada; second generation and higher). Both groups rested for 10 min and then performed 50 min of moderate-intensity exercise at 200 W m-2 , followed by 30 min of recovery in hot, dry heat (35°C, 20% relative humidity). Local cutaneous vascular conductance (CVC%max ) and sweat rate (SR) were measured at two forearm skin sites treated with either lactated Ringer solution (control) or 10 mm NG -nitro-l-arginine methyl ester (l-NAME, a nitric oxide (NO) synthase inhibitor). l-NAME significantly reduced CVC%max throughout rest, exercise and recovery in both groups (both P < 0.001). However, there were no significant main effects for the contribution of NO to CVC%max between groups (all P > 0.500). l-NAME significantly reduced local SR in both groups (both P < 0.050). The contribution of NO to SR was similar between groups such that l-NAME reduced SR relative to control at 40 and 50 min into exercise (both P < 0.05). We demonstrate that ethnicity per se does not influence NO-dependent cutaneous vasodilatation and sweating in healthy young men of black-African and Caucasian descent during exercise in dry heat.
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Affiliation(s)
- Caroline M Muia
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Madison D Schmidt
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
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