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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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Nakata T, Shibasaki M, Nishimura Y, Kinoshita T, Hashizaki T, Kamijo YI, Kouda K, Umemoto Y, Tajima F. Quantification of catecholamine neurotransmitters released from cutaneous vasoconstrictor nerve endings in men with cervical spinal cord injury. Am J Physiol Regul Integr Comp Physiol 2023; 324:R345-R352. [PMID: 36693170 DOI: 10.1152/ajpregu.00063.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Control of cutaneous circulation is critically important to maintain thermoregulation, especially in individuals with cervical spinal cord injury (CSCI) who have no or less central thermoregulatory drive. However, the peripheral vasoconstrictor mechanism and capability have not been fully investigated after CSCI. Post- and presynaptic sensitivities of the cutaneous vasoconstrictor system were investigated in 8 CSCI and 7 sedentary able-bodied (AB) men using an intradermal microdialysis technique. Eight doses of norepinephrine (NE, 10-8 to 10-1 M) and five doses of tyramine (TY, 10-8, 10-5 to 10-2 M) were administered into the anterior right and left thigh, respectively. Endogenous catecholamines, noradrenaline, and dopamine, collected at the TY site, were determined by high-performance liquid chromatography with electrochemical detection. Regardless of vasoconstrictor agents, cutaneous vascular conductance decreased dose-dependently and responsiveness was similar between the groups (NE: Group P = 0.255, Dose P = 0.014; TY: Group P = 0.468, Dose P < 0.001), whereas the highest dose of each drug induced cutaneous vasodilation. Administration of TY promoted the release of noradrenaline and dopamine in both groups. Notably, the amount of noradrenaline released was similar between the groups (P = 0.819), although the concentration of dopamine was significantly greater in individuals with CSCI than in AB individuals (P = 0.004). These results suggest that both vasoconstrictor responsiveness and neural functions are maintained after CSCI, and dopamine in the skin is likely to induce cutaneous vasodilation.
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Affiliation(s)
- Tomonori Nakata
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | | | - Yukihide Nishimura
- Department of Rehabilitation Medicine, Iwate Medical University, Wakayama, Japan
| | - Tokio Kinoshita
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan.,Division of Rehabilitation, Wakayama Medical University Hospital, Wakayama, Japan
| | - Takamasa Hashizaki
- Division of Rehabilitation, Wakayama Medical University Hospital, Wakayama, Japan
| | - Yoshi-Ichiro Kamijo
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan.,Department of Rehabilitation Medicine, Dokkyo Medical University Saitama Medical Center, Saitama, Japan
| | - Ken Kouda
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | - Yasunori Umemoto
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | - Fumihiro Tajima
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
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3
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Limberg JK, Johansson RE, Carter KJ, Peltonen GL, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Walker BJ, Schrage WG. Preserved β-adrenergic-mediated vasodilation in skeletal muscle of young adults with obesity despite shifts in cyclooxygenase and nitric oxide synthase. Am J Physiol Heart Circ Physiol 2022; 322:H25-H35. [PMID: 34738833 PMCID: PMC8698505 DOI: 10.1152/ajpheart.00449.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight (n = 36) and adults with obesity (n = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [NG-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups (P = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight (P = 0.03) but not adults with obesity (P = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC (P < 0.01) and this response was lost with concurrent l-NMMA (P = 0.67). In contrast, neither ketorolac (P = 0.81) nor ketorolac + l-NMMA (P = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity.NEW & NOTEWORTHY We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.
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Affiliation(s)
- Jacqueline K. Limberg
- 1Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri,2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | | | - Katrina J. Carter
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | - Garrett L. Peltonen
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,3School of Nursing and Kinesiology, Western New Mexico University, Silver City, New Mexico
| | - John W. Harrell
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,4711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio
| | - J. Mikhail Kellawan
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,5Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Marlowe W. Eldridge
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,6Department of Pediatrics, University of Wisconsin, Madison, Wisconsin
| | - Joshua J. Sebranek
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
| | - Benjamin J. Walker
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
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Amano T, Fujii N, Kenny GP, Nishiyasu T, Inoue Y, Kondo N. The relative contribution of α- and β-adrenergic sweating during heat exposure and the influence of sex and training status. Exp Dermatol 2020; 29:1216-1224. [PMID: 33015872 DOI: 10.1111/exd.14208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/14/2020] [Accepted: 09/27/2020] [Indexed: 02/04/2023]
Abstract
While human eccrine sweat glands respond to adrenergic agonists, there remains a paucity of information on the factors modulating this response. Thus, we assessed the relative contribution of α- and β-adrenergic sweating during a heat exposure and as a function of individual factors of sex and training status. α- and β-adrenergic sweating was assessed in forty-eight healthy young men (n = 35) and women (n = 13) including endurance-trained (n = 12) and untrained men (n = 12) under non-heat exposure (temperate, 25°C; n = 17) and heat exposure (hot, 35°C; n = 48) conditions using transdermal iontophoresis of phenylephrine (α-adrenergic agonist) and salbutamol (β-adrenergic agonist) on the ventral forearm, respectively. Adrenergic sweating was also measured after iontophoretic administration of atropine (muscarinic receptor antagonist) or saline (control) to evaluate how changes in muscarinic receptor activity modulate the adrenergic response to a heat exposure (n = 12). α- and β-adrenergic sweating was augmented in hot compared with temperate conditions (both P ≤ .014), albeit the relative increase was greater in β (~5.4-fold)- as compared to α (~1.5-fold)-adrenergic-mediated sweating response. However, both α- and β-adrenergic sweating was abolished by atropinization (P = .001). Endurance-trained men showed an augmentation in α- (P = .043) but not β (P = .960)-adrenergic sweating as compared to untrained men. Finally, a greater α- and β-adrenergic sweating response (both P ≤ .001) was measured in habitually active men than in women. We show that heat exposure augments α-and β-adrenergic sweating differently via mechanisms associated with altered muscarinic receptor activity. Sex and training status modulate this response.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
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Arnold JT, Lloyd AB, Bailey SJ, Fujimoto T, Matsutake R, Takayanagi M, Nishiyasu T, Fujii N. The nitric oxide dependence of cutaneous microvascular function to independent and combined hypoxic cold exposure. J Appl Physiol (1985) 2020; 129:947-956. [DOI: 10.1152/japplphysiol.00487.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
When separated from local cooling, whole body cooling elicited cutaneous reflex vasoconstriction via mechanisms independent of nitric oxide removal. Hypoxia elicited cutaneous vasodilatation via mechanisms mediated primarily by nitric oxide synthase, rather than xanthine oxidase-mediated nitrite reduction. Cold-induced vasoconstriction was blunted by the opposing effect of hypoxic vasodilatation, whereas the underpinning mechanisms did not interrelate in the absence of local cooling. Full vasoconstriction was restored with nitric oxide synthase inhibition.
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Affiliation(s)
- Josh T. Arnold
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Alex B. Lloyd
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Stephen J. Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Tomomi Fujimoto
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan
- Institute for Human Movement and Medical Science, Niigata University of Health and Welfare, Niigata, Japan
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ryoko Matsutake
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | | | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
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Fujii N, McGarr GW, Amano T, Sigal RJ, Boulay P, Nishiyasu T, Kenny GP. Ageing augments β-adrenergic cutaneous vasodilatation differently in men and women, with no effect on β-adrenergic sweating. Exp Physiol 2020; 105:1720-1729. [PMID: 32818310 DOI: 10.1113/ep088583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 08/10/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? β-Adrenergic receptor activation modulates cutaneous vasodilatation and sweating in young adults. In this study, we assessed whether age-related differences in β-adrenergic regulation of these responses exist and whether they differ between men and women. What is the main finding and its importance? We showed that ageing augmented β-adrenergic cutaneous vasodilatation, although the pattern of response differed between men and women. Ageing had no effect on β-adrenergic sweating in men or women. Our findings advance our understanding of age-related changes in the regulation of cutaneous vasodilatation and sweating and provide new directions for research on the significance of enhanced β-adrenergic cutaneous vasodilatation in older adults. ABSTRACT β-Adrenergic receptor agonists, such as isoprenaline, can induce cutaneous vasodilatation and sweating in young adults. Given that cutaneous vasodilatation and sweating responses to whole-body heating and to pharmacological agonists, such as acetylcholine, ATP and nicotine, can differ in older adults, we assessed whether ageing also modulates β-adrenergic cutaneous vasodilatation and sweating and whether responses differ between men and women. In the context of the latter, prior reports showed that the effects of ageing on cutaneous vasodilatation (evoked with ATP and nicotine) and sweating (stimulated by acetylcholine) were sex dependent. Thus, in the present study, we assessed the role of β-adrenergic receptor activation on forearm cutaneous vasodilatation and sweating in 11 young men (24 ± 4 years of age), 11 young women (23 ± 5 years of age), 11 older men (61 ± 8 years of age) and 11 older women (60 ± 8 years of age). Initially, a high dose (100 µm) of isoprenaline was administered via intradermal microdialysis for 5 min to induce maximal β-adrenergic sweating. Approximately 60 min after the washout period, three incremental doses of isoprenaline were administered (1, 10 and 100 µm, each for 25 min) to assess dose-dependent cutaneous vasodilatation. Isoprenaline-mediated cutaneous vasodilatation was greater in both older men and older women relative to their young counterparts. Augmented cutaneous vasodilatory responses were observed at 1 and 10 µm in women and at 100 µm in men. Isoprenaline-mediated sweating was unaffected by ageing, regardless of sex. We show that ageing augments β-adrenergic cutaneous vasodilatation differently in men and women, without influencing β-adrenergic sweating.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Niigata, Japan
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Ontario, Canada
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Amano T, Sekihara S, Fujii N, Kenny GP, Inoue Y, Kondo N. Does the iontophoretic application of bretylium tosylate modulate sweating during exercise in the heat in habitually trained and untrained men? Exp Physiol 2020; 105:1692-1699. [PMID: 32776611 DOI: 10.1113/ep088797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/07/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the administration of the adrenergic presynaptic release inhibitor bretylium tosylate modulate sweating during exercise in the heat, and does this response differ between habitually trained and untrained men? What is the main finding and its importance? Iontophoretic administration of bretylium tosylate attenuates sweating during exercise in the heat in habitually trained and untrained men. However, a greater reduction occurred in trained men. The findings demonstrate a role for cutaneous adrenergic nerves in the regulation of eccrine sweating during exercise in the heat and highlight a need to advance our understanding of neural control of human eccrine sweat gland activity. ABSTRACT We recently reported an influence of cutaneous adrenergic nerves on eccrine sweat production in habitually trained men performing an incremental exercise bout in non-heat stress conditions. Based on an assumption that increasing heat stress induces cholinergic modulation of sweating, we evaluated the hypothesis that the contribution of cutaneous adrenergic nerves on sweating would be attenuated during exercise in the heat. Twenty young habitually trained and untrained men (n = 10/group) underwent three successive bouts of 15 min of light-, moderate- and vigorous-intensity cycling (equivalent to 30, 50, and 70% of peak oxygen uptake ( V ̇ O 2 peak ) respectively), each separated by a 15 min recovery while wearing a perfusion suit perfused with warm water (43°C). Sweat rate (ventilated capsule) was measured continuously at two bilateral forearm skin sites treated with 10 mm bretylium tosylate (an inhibitor of neurotransmitter release from adrenergic nerve terminals) and saline (control) via transdermal iontophoresis. A greater sweat rate was measured during vigorous exercise only in trained as compared to untrained men (P = 0.014). In both groups, sweating was reduced at the bretylium tosylate versus control sites, albeit the magnitude of reduction was greater in the trained men (P ≤ 0.024). These results suggest that cutaneous adrenergic nerves modulate sweating during exercise performed under a whole-body heat stress, albeit a more robust response occurs in trained men. While it is accepted that a cholinergic mechanism plays a primary role in the regulation of sweating during an exercise-heat stress, our findings highlight the need for additional studies aimed at understanding the neural control of human eccrine sweating.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Shin Sekihara
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
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Abstract
The mechanism by which nitric oxide synthase (NOS) inhibition impacts human sweating is unknown. We tested the hypothesis that the activation of NOS and release on nitric oxide acts to open K+ channels and enhance sweat gland output. Local sweat rate (LSR) was measured with a small sweat capsule mounted on the skin while sweating was initiated by intradermal electrical stimulation. Sigmoid shape stimulus-response curves were generated by plotting the area under the LSR-time curve (LSR AUC) versus log10 stimulus frequency and normalized to the peak AUC response during control trials. NOS inhibition alone reduced the peak sweat rate response to 81.5 ± 4.5% peak LSR AUC of that seen with lactated Ringer's (P = 0.0004). Fifty mM of tetraethylammonium chloride (TEA) alone reduced peak LSR (0.317 ± 0.060 vs. 0.511 ± 0.104 mg·min-1·cm-2, P = 0.03) and the peak LSR AUC response from 0.193 ± 0.170 to 0.158 ± 0.127 mg·cm-2 (P = 0.004). Delivery of a 20 mM nitro-l-arginine methyl ester (l-NAME) following 50 mM TEA produced a further decrease in the peak LSR AUC response to 0.095 ± 0.064 mg·cm-2 (≈20% reduction, P = 0.0145). These data support the hypothesis that sudomotor control of sweat gland activity is locally modulated by a functioning NOS system that appears to be additive and independent to the effect of blockade of K+ channels with TEA.NEW & NOTEWORTHY The contribution of nitric oxide synthase (NOS) to the process of cholinergic-mediated human eccrine sweat production is unclear. Using a novel model for cholinergic-mediated sweating in humans, I demonstrate that blocking the NOS system led to a reduction in local sweat rate (LSR). This reduction in LSR was maintained in the presence of K+ channel blockade with tetraethylammonium.
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Affiliation(s)
- Gary W Mack
- Department of Exercise Sciences, Brigham Young University, Provo, Utah
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Fujii N, McGarr GW, Ghassa R, Schmidt MD, McCormick JJ, Nishiyasu T, Kenny GP. Sex-differences in cholinergic, nicotinic, and β-adrenergic cutaneous vasodilation: Roles of nitric oxide synthase, cyclooxygenase, and K + channels. Microvasc Res 2020; 131:104030. [PMID: 32531353 DOI: 10.1016/j.mvr.2020.104030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 05/22/2020] [Accepted: 06/05/2020] [Indexed: 12/15/2022]
Abstract
Previous studies indicate that sex-related differences exist in the regulation of cutaneous vasodilation, however, the mechanisms remain unresolved. We assessed if sex-differences in young adults exist for cholinergic, nicotinic, and β-adrenergic cutaneous vasodilation with a focus on nitric oxide synthase (NOS), cyclooxygenase (COX), and K+ channel mechanisms. In twelve young men and thirteen young women, four intradermal forearm skin sites were perfused with the following: 1) lactated Ringer's solution (control), 2) 10 mM Nω-nitro-l-arginine, a non-selective NOS inhibitor, 3) 10 mM ketorolac, a non-selective COX inhibitor, or 4) 50 mM BaCl2, a nonspecific K+ channel blocker. At all four sites, cutaneous vasodilation was induced by 1) 10 mM nicotine, a nicotinic receptor agonist, 2) 100 μM isoproterenol, a nonselective β-adrenergic receptor agonist, and 3) 2 mM and 2000 mM acetylcholine, an acetylcholine receptor agonist. Nicotine and isoproterenol were administered for 3 min, whereas each acetylcholine dose was administered for 25 min. Regardless of treatment site, cutaneous vasodilation in response to nicotine and a high dose of acetylcholine (2000 mM) were lower in women than men. By contrast, isoproterenol induced cutaneous vasodilation was greater in women vs. men. Irrespective of sex, NOS inhibition or K+ channel blockade attenuated isoproterenol-mediated cutaneous vasodilation, whereas K+ channel blockade decreased nicotine-induced cutaneous vasodilation. Taken together, our findings indicate that while the mechanisms underlying cutaneous vasodilation are comparable between young men and women, sex-related differences in the magnitude of cutaneous vasodilation do exist and this response differs as a function of the receptor agonist.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada; Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Reem Ghassa
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Madison D Schmidt
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Does α 1-adrenergic receptor blockade modulate sweating during incremental exercise in young endurance-trained men? Eur J Appl Physiol 2020; 120:1123-1129. [PMID: 32221728 DOI: 10.1007/s00421-020-04351-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 03/18/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE Human eccrine sweat glands respond to α1-adrenergic receptor agonists. We recently reported that adrenergic mechanisms contribute to sweating in endurance-trained men during an incremental exercise to volitional fatigue. However, it remains unclear if this response is mediated by α1-adrenergic receptor activation. METHODS Twelve endurance-trained men performed an incremental cycling bout until exhaustion while wearing a water-perfused suit to clamp skin temperature at ~ 34 °C. Bilateral forearm sweat rates were measured wherein the distal area was treated with either 1% terazosin (α1-adrenergic receptor antagonist) or saline solution on the opposite limb (Control) via transdermal iontophoresis. We also measured proximal bilateral forearm sweat rate in untreated sites to confirm that no between-limb differences in forearm sweat rate occurred. Once sweat rate returned to pre-exercise resting levels at ~ 20 min postexercise, 0.25% phenylephrine (α1-adrenergic receptor agonist) was iontophoretically administered to skin to verify α1-adrenergic receptor blockade. RESULTS Sweat rates at the proximal untreated right and left forearm sites were similar during exercise (interaction, P = 0.581). Similarly, no effect of terazosin on sweat rate was measured relative to control site (interaction, P = 0.848). Postexercise administration of phenylephrine increased sweat rate at the control site (0.08 ± 0.09 mg cm-2 min-1), which was suppressed by ~ 90% at the terazosin-treated site (0.01 ± 0.02 mg cm-2 min-1) (P = 0.026), confirming that α1-adrenergic receptor blockade was intact. CONCLUSION Our findings demonstrate that α1-adrenergic receptors located at eccrine sweat glands do not contribute to eccrine sweating during incremental exercise in young endurance-trained men.
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Amano T, Igarashi A, Fujii N, Hiramatsu D, Inoue Y, Kondo N. β-Adrenergic receptor blockade does not modify non-thermal sweating during static exercise and following muscle ischemia in habitually trained individuals. Eur J Appl Physiol 2018; 118:2669-2677. [DOI: 10.1007/s00421-018-3993-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 09/12/2018] [Indexed: 11/29/2022]
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Amano T, Fujii N, Inoue Y, Kondo N. Cutaneous adrenergic nerve blockade attenuates sweating during incremental exercise in habitually trained men. J Appl Physiol (1985) 2018; 125:1041-1050. [PMID: 30024338 DOI: 10.1152/japplphysiol.00370.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
It remains unknown whether cutaneous adrenergic nerves functionally contribute to sweat production during exercise. This study examined whether cutaneous adrenergic nerve blockade attenuates sweating during incremental exercise, specifically in habitually trained individuals. Accordingly, 10 habitually trained and 10 untrained males (V̇o2max: 56.7 ± 5.4 and 38.9 ± 6.7 ml·kg-1·min-1, respectively; P < 0.001) performed incremental semirecumbent cycling (20 W/min) until exhaustion. Sweat rates (ventilated capsule) were measured at two bilateral forearm skin sites on which either 10 mM bretylium tosylate (BT) (an inhibitor of neurotransmitter release from sympathetic adrenergic nerve terminals) or saline (Control) was transdermally administered via iontophoresis. BT treatment delayed sweating onset in both groups (∼0.66 min; P = 0.001) and suppressed the sweat rate relative to the Control treatment at ≥70% relative total exercise time in trained individuals (each 10% increment; all P ≤ 0.009) but not in untrained counterparts ( P = 0.122, interaction between relative time × treatment). Changes in total sweat production at the BT site relative to the Control site were greater in trained individuals than in untrained counterparts (area under the curve, -0.86 ± 0.67 and -0.22 ± 0.39 mg/cm2, respectively; P = 0.023). In conclusion, we demonstrated that cutaneous adrenergic nerves do modulate sweating during incremental exercise, which appeared to be more apparent in habitually trained men (e.g., ≥70% maximum workload). Although our results indicated that habitual exercise training may augment neural adrenergic sweat production during incremental exercise, additional studies are required to confirm this possibility. NEW & NOTEWORTHY We demonstrated for the first time that cutaneous adrenergic nerves do modulate sweating during high-intensity exercise in humans (≥70% maximum workload). In addition, neural adrenergic sweating appeared to be greater in habitually trained individuals than in untrained counterparts, although further studies are necessary to confirm such a possibility. Nonetheless, the observations presented herein advance our understanding on human thermoregulation while providing new evidence for the neutral mediation of adrenergic sweating during exercise.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University , Niigata , Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba City , Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University , Osaka , Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University , Kobe , Japan
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Amano T, Shitara Y, Fujii N, Inoue Y, Kondo N. Evidence for β-adrenergic modulation of sweating during incremental exercise in habitually trained males. J Appl Physiol (1985) 2017; 123:182-189. [DOI: 10.1152/japplphysiol.00220.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/20/2017] [Accepted: 05/01/2017] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to determine the β-adrenergic contribution to sweating during incremental exercise in habitually trained males. Nine habitually trained and 11 untrained males performed incremental cycling until exhaustion (20 W/min). Bilateral forearm sweat rates (ventilated capsule) were measured at two skin sites that were transdermally administered via iontophoresis with either 1% propranolol (Propranolol, a nonselective β-adrenergic receptor antagonist) or saline (Control). The sweat rate was evaluated as a function of both relative (percentage of maximum workload) and absolute exercise intensities. The sweat rate at the Propranolol site was lower than the control during exercise at 80 (0.57 ± 0.21 and 0.45 ± 0.19 mg·cm−2·min−1 for Control and Propranolol, respectively) and 90% (0.74 ± 0.22 and 0.65 ± 0.17 mg·cm−2·min−1, respectively) of maximum workload in trained males (all P < 0.05). By contrast, no between-site differences in sweat rates were observed in untrained counterparts (all P > 0.05). At the same absolute intensity, higher sweat rates on the control site were observed in trained males relative to the untrained during exercise at 160 (0.23 ± 0.20 and 0.04 ± 0.05 mg·cm−2·min−1 for trained and untrained, respectively) and 180 W (0.40 ± 0.20 and 0.13 ± 0.13 mg·cm−2·min−1, respectively) (all P < 0.05), whereas this between-group difference was not observed at the Propranolol site (all P > 0.05). We show that the β-adrenergic mechanism does modulate sweating during exercise at a submaximal high relative intensity in habitually trained males. The β-adrenergic mechanism may in part contribute to the greater sweat production in habitually trained males than in untrained counterparts during exercise. NEW & NOTEWORTHY We demonstrated for the first time that the β-adrenergic mechanism does modulate sweating (i.e., β-adrenergic sweating) during exercise using a localized β-adrenoceptor blockade in humans in vivo. β-Adrenergic sweating was evident in habitually trained individuals during exercise at a submaximal high relative intensity (80–90% maximal work). This observation advances our understanding of human thermoregulation during exercise and of the mechanism that underlies sweat gland adaptation to habitual exercise training.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Yosuke Shitara
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Naoto Fujii
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan; and
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
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Louie JC, Fujii N, Meade RD, McNeely BD, Kenny GP. The roles of K Ca, K ATP, and K V channels in regulating cutaneous vasodilation and sweating during exercise in the heat. Am J Physiol Regul Integr Comp Physiol 2017; 312:R821-R827. [PMID: 28254750 DOI: 10.1152/ajpregu.00507.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/13/2017] [Accepted: 02/28/2017] [Indexed: 01/11/2023]
Abstract
We recently showed the varying roles of Ca2+-activated (KCa), ATP-sensitive (KATP), and voltage-gated (KV) K+ channels in regulating cholinergic cutaneous vasodilation and sweating in normothermic conditions. However, it is unclear whether the respective contributions of these K+ channels remain intact during dynamic exercise in the heat. Eleven young (23 ± 4 yr) men completed a 30-min exercise bout at a fixed rate of metabolic heat production (400 W) followed by a 40-min recovery period in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance (CVC) and local sweat rate were assessed at four forearm skin sites perfused via intradermal microdialysis with: 1) lactated Ringer solution (control); 2) 50 mM tetraethylammonium (nonspecific KCa channel blocker); 3) 5 mM glybenclamide (selective KATP channel blocker); or 4) 10 mM 4-aminopyridine (nonspecific KV channel blocker). Responses were compared at baseline and at 10-min intervals during and following exercise. KCa channel inhibition resulted in greater CVC versus control at end exercise (P = 0.04) and 10 and 20 min into recovery (both P < 0.01). KATP channel blockade attenuated CVC compared with control during baseline (P = 0.04), exercise (all P ≤ 0.04), and 10 min into recovery (P = 0.02). No differences in CVC were observed with KV channel inhibition during baseline (P = 0.15), exercise (all P ≥ 0.06), or recovery (all P ≥ 0.14). With the exception of KV channel inhibition augmenting sweating during baseline (P = 0.04), responses were similar to control with all K+ channel blockers during each time period (all P ≥ 0.07). We demonstrated that KCa and KATP channels contribute to the regulation of cutaneous vasodilation during rest and/or exercise and recovery in the heat.
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Affiliation(s)
- Jeffrey C Louie
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and.,Institute of Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Brendan D McNeely
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
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