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Okamoto Y, Otsuka J, Aoki M, Amano T. Transdermal iontophoretic application of l-NAME is available in sweating research induced by heat stress in young healthy adults. Nitric Oxide 2023; 138-139:96-103. [PMID: 37619814 DOI: 10.1016/j.niox.2023.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 08/10/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Iontophoretic transdermal administration of NG-nitro-l-arginine methyl ester hydrochloride [l-NAME, a nitric oxide synthase (NOS) inhibitor] has been used as a non-invasive evaluation of NOS-dependent mechanisms in human skin. However, the availability has yet to be investigated in sweating research. Prior observations using invasive techniques (e.g., intradermal microdialysis technique) to administer l-NAME have implicated that NOS reduces sweating induced by heat stress but rarely influences the response induced by the administration of cholinergic muscarinic receptor agonists. Therefore, we investigated whether the transdermal iontophoretic administration of l-NAME modulates sweating similar to those prior observations. Twenty young healthy adults (10 males, 10 females) participated in two experimental protocols on separate days. Before each protocol, saline (control) and 1% l-NAME were bilaterally administered to the forearm skin via transdermal iontophoresis. In protocol 1, 0.001% and 1% pilocarpine were iontophoretically administered at l-NAME-treated and untreated sites. In protocol 2, passive heating was applied by immersing the lower limbs in hot water (43 °C) until the rectal temperature increased by 0.8 °C above baseline. The sweat rate was continuously measured throughout both protocols. Pilocarpine-induced sweat rate was not significantly different between the control and l-NAME-treated sites in both pilocarpine concentrations (P ≥ 0.316 for the treatment effect and interaction of treatment and pilocarpine concentration). The sweat rate during passive heating was attenuated at the l-NAME-treated site relative to the control (treatment effect, P = 0.020). Notably, these observations are consistent with prior sweating studies administrating l-NAME into human skin using intradermal microdialysis techniques. Based on the similarity of our results with already known observations, we conclude that transdermal iontophoresis of l-NAME is a valid non-invasive technique for the investigation of the mechanisms of sweating related to NOS during heat stress.
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Affiliation(s)
- Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Junto Otsuka
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Mao Aoki
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan.
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Fujii N, Hatam K, McGarr GW, Meade RD, Boulay P, Nishiyasu T, Kenny GP. Exogenous Activation of Protease-Activated Receptor 2 Attenuates Cutaneous Vasodilatation and Sweating in Older Men Exercising in the Heat. Skin Pharmacol Physiol 2019; 32:235-243. [PMID: 31220834 DOI: 10.1159/000500643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 04/26/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Protease-activated receptor 2 (PAR2) exists in the cutaneous vasculature and eccrine sweat glands. We previously showed that in young habitually active men, exogenous PAR2 activation via the agonist SLIGKV-NH2 had no effect on heat loss responses of cutaneous vasodilatation and sweating during rest or exercise in the heat. However, ageing is associated with altered mechanisms governing these responses. Thus, the effect of exogenous PAR2 activation on cutaneous vasodilatation and sweating in older individuals may differ from that in young adults. METHODS Local cutaneous vascular conductance (CVC) and sweat rate were measured in 9 older males (62 ± 4 years) at four forearm skin sites treated with the following: (1) lactated Ringer solution (control), (2) 0.05 mM, (3) 0.5 mM, or (4) 5 mM SLIGKV-NH2. Measurements were performed while participants rested in a non-heat-stress environment (25°C) for ∼60 min and an additional 50 min thereafter in the heat (40°C). Participants then performed 50 min of cycling at a fixed metabolic heat load of 200 W/m2 (to maintain the same thermal drive for heat loss between participants) followed by a 30-min recovery. RESULTS CVC during non-heat-stress resting was elevated from the control site with 5 mM SLIGKV-NH2 (p ≤ 0.05), but this response was not observed during ambient heat exposure. By contrast, 5 mM SLIGKV-NH2 lowered CVC during the early stage (10 and 20 min) of exercise compared to the control site (all p ≤ 0.05). Although sweating during non-heat-stressed and heat-stressed resting was not affected by any dose of SLIGKV-NH2, it was reduced with all SLIGKV-NH2 doses relative to the control site during and following exercise (all p ≤ 0.05). CONCLUSION We show that while exogenous PAR2 activation induces cutaneous vasodilatation at rest under non-heat-stressed conditions, it attenuates cutaneous vasodilatation and sweating during and following an exercise-induced heat stress in older men.
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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, Japan,
| | - Kion Hatam
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Québec, 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, Ontario, Canada
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Meade RD, Fujii N, McGarr GW, Alexander LM, Boulay P, Sigal RJ, Kenny GP. Local arginase inhibition does not modulate cutaneous vasodilation or sweating in young and older men during exercise. J Appl Physiol (1985) 2019; 126:1129-1137. [PMID: 30653418 DOI: 10.1152/japplphysiol.00657.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Age-related impairments in cutaneous vascular conductance (CVC) and sweat rate (SR) during exercise may result from increased arginase activity, which can attenuate endogenous nitric oxide (NO) production. We therefore evaluated whether arginase inhibition modulates these heat-loss responses in young (n = 9, 23 ± 3 yr) and older (n = 9, 66 ± 6 yr) men during two 30-min bouts of moderate-intensity cycling (Ex1 and Ex2) in the heat (35°C). CVC and SR were measured at forearm skin sites perfused with 1) lactated Ringer's (control), 2) NG-nitro-L-arginine methyl ester (L-NAME; NO synthase-inhibited), or 3) Nω-hydroxy-nor-arginine and S-(2-boronoethyl)-l-cysteine (Nor-NOHA + BEC; arginase-inhibited). In both groups, CVC was reduced at L-NAME relative to control and Nor-NOHA + BEC (both P < 0.01). Likewise, SR was attenuated with L-NAME compared with control and Nor-NOHA + BEC during each exercise bout in the young men (all P ≤ 0.05); however, no influence of treatment on SR in the older men was observed (P = 0.14). Based on these findings, we then evaluated responses in 7 older men (64 ± 7 yr) during passively induced elevations in esophageal temperature (∆Tes) equal to those in Ex1 (0.6°C) and Ex2 (0.8°C). L-NAME reduced CVC by 18 ± 20% CVCmax at a ∆Tes of 0.8°C (P = 0.03) compared with control, whereas Nor-NOHA + BEC augmented CVC by 20 ± 18% CVCmax, on average, throughout heating (both P ≤ 0.03). SR was not influenced by either treatment (P = 0.80) Thus, arginase inhibition does not modulate CVC or SR during exercise in the heat but, consistent with previous findings, does augment CVC in older men during passive heating. NEW & NOTEWORTHY In the current study, we demonstrate that local arginase inhibition does not influence forearm cutaneous vasodilatory and sweating responses in young or older men during exercise-heat stress. Consistent with previous findings, however, we observed augmented cutaneous blood flow with arginase inhibition during whole-body passive heat stress. Thus, arginase differentially affects cutaneous vasodilation depending on the mode of heat stress but does not influence sweating during exercise or passive heating.
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Affiliation(s)
- Robert D Meade
- 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 City , Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, Pennsylvania State University , University Park, Pennsylvania
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke , Sherbrooke, QC , Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada.,Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary , Calgary, AB , Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute , Ottawa, ON , Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute , Ottawa, ON , Canada
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