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McGarr GW, Muia CM, Saci S, Fujii N, Kenny GP. K Ca channels are major contributors to ATP-induced cutaneous vasodilation in healthy older adults. Microvasc Res 2020; 133:104096. [PMID: 33058899 DOI: 10.1016/j.mvr.2020.104096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 08/30/2020] [Accepted: 10/08/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To examine the contributions of calcium-activated K+ (KCa) channels and nitric oxide synthase (NOS) to adenosine triphosphate (ATP)-induced cutaneous vasodilation in healthy older adults. METHODS In eleven older adults (69 ± 2 years, 5 females), cutaneous vascular conductance, normalized to maximum vasodilation (%CVCmax) was assessed at four dorsal forearm skin sites that were continuously perfused with either 1) lactated Ringer solution (Control), 2) 50 mM tetraethylammonium (TEA, KCa channel blocker), 3) 10 mM Nω-nitro-L-arginine (L-NNA, NOS inhibitor), or 4) combined 50 mM TEA +10 mM L-NNA, via microdialysis. Local skin temperature was fixed at 33 °C at all sites with local heaters throughout the protocol while the cutaneous vasodilator response was assessed during coadministration of ATP (0.03, 0.3, 3, 30, 300 mM; 20 min per dose), followed by 50 mM sodium nitroprusside and local skin heating to 43 °C to achieve maximum vasodilation (20-30 min). RESULTS Blockade of KCa channels blunted %CVCmax relative to Control from 0.3 to 300 mM ATP (All P < 0.05). A similar response was observed for the combined KCa channel blockade and NOS inhibition site from 3 to 300 mM ATP (All P < 0.05). Conversely, NOS inhibition alone did not influence %CVCmax across all ATP doses (All P > 0.05). CONCLUSION In healthy older adults, KCa channels play an important role in modulating ATP-induced cutaneous vasodilation, while the NOS contribution to this response is negligible.
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Affiliation(s)
- Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Caroline M Muia
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Samah Saci
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
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Fujii N, McGarr GW, Sigal RJ, Boulay P, Nishiyasu T, Kenny GP. Ageing augments nicotinic and adenosine triphosphate-induced, but not muscarinic, cutaneous vasodilatation in women. Exp Physiol 2019; 104:1801-1807. [PMID: 31602716 DOI: 10.1113/ep088144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 10/08/2019] [Indexed: 12/22/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does ageing augment muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in women? What is the main finding and its importance? Ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women. This will stimulate future studies assessing the pathophysiological significance of the augmented microvascular responsiveness in older women compared to their young counterparts. ABSTRACT We previously reported that ageing attenuates adenosine triphosphate (ATP)-induced, but not muscarinic and nicotinic, cutaneous vasodilatation in men, and that ageing may augment cutaneous vascular responses in women. In the present study, we evaluated the hypothesis that ageing augments muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in healthy women. In 11 young (23 ± 5 years) and 11 older (60 ± 8 years) women, cutaneous vascular conductance was evaluated at three forearm skin sites that were perfused with (1) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mm), (2) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mm), or (3) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mm). Each agonist was administered for 25 min per dose. Methacholine-induced increases in cutaneous vascular conductance were not different between groups at all doses (all P > 0.05). However, a nicotine-induced elevation in cutaneous vascular conductance at the lowest concentration (1.2 mm) was greater in older vs. young women (43 ± 15 vs. 26 ± 10%max, P = 0.04). ATP-induced increases in cutaneous vascular conductance at moderate and high doses (3 and 30 mm) were also greater in older relative to young women (3 mm, 44 ± 11 vs. 28 ± 10%max, P = 0.02; 30 mm, 83 ± 14 vs. 64 ± 17%max, P = 0.05). Therefore, ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women.
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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
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - 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.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, 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, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Fujii N, Nishiyasu T, Sigal RJ, Boulay P, McGarr GW, Kenny GP. Aging attenuates adenosine triphosphate-induced, but not muscarinic and nicotinic, cutaneous vasodilation in men. Microcirculation 2018; 25:e12462. [PMID: 29846993 DOI: 10.1111/micc.12462] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 05/13/2018] [Accepted: 05/28/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVE We evaluated the hypothesis that aging attenuates muscarinic, nicotinic, and ATP-related cutaneous vasodilation. METHODS In 11 young (24 ± 4 years) and 11 older males (61 ± 8 years), CVC was assessed at 3 forearm skin sites that were infused with either: (i) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mmol/L), (ii) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mmol/L), or (iii) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mmol/L). Each agonist was administered for 25 minutes per dose. RESULTS We showed that CVC at all doses of methacholine did not differ between groups. Similarly, no between-group differences in CVC were observed during nicotine administration at all doses administered. By contrast, while no differences in CVC were measured during the administration of ATP at low (0.03 and 0.3 mmol/L) or high (300 mmol/L) concentrations, CVC was reduced in the older relative to the young males at moderate concentrations of ATP (3 mmol/L: 23 ± 6 vs 40 ± 13%max, 30 mmol/L: 62 ± 11 vs 83 ± 8%max, both P ≤ .05). CONCLUSIONS We show that aging attenuates ATP-induced, but not muscarinic or nicotinic, cutaneous vasodilation in men.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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Fromy B, Josset-Lamaugarny A, Aimond G, Pagnon-Minot A, Marics I, Tattersall GJ, Moqrich A, Sigaudo-Roussel D. Disruption of TRPV3 Impairs Heat-Evoked Vasodilation and Thermoregulation: A Critical Role of CGRP. J Invest Dermatol 2018; 138:688-696. [DOI: 10.1016/j.jid.2017.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/08/2017] [Accepted: 10/08/2017] [Indexed: 12/24/2022]
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Fujii N, Meade RD, McNeely BD, Nishiyasu T, Sigal RJ, Kenny GP. Type 2 diabetes specifically attenuates purinergic skin vasodilatation without affecting muscarinic and nicotinic skin vasodilatation and sweating. Exp Physiol 2018; 103:212-221. [DOI: 10.1113/ep086694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/28/2017] [Indexed: 01/12/2023]
Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport Sciences; University of Tsukuba; Tsukuba Japan
- 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
| | - Brendan D. McNeely
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences; University of Tsukuba; Tsukuba 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
- Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa Ontario Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit; University of Ottawa; Ottawa Ontario Canada
- Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa Ontario Canada
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Fujii N, Meade RD, Louie JC, Akbari P, Boulay P, Sigal RJ, Kenny GP. Effect of P2 receptor blockade on cutaneous vasodilation during rest and exercise in the heat in young men. Appl Physiol Nutr Metab 2017; 43:312-315. [PMID: 29272631 DOI: 10.1139/apnm-2017-0700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We assessed the role of purinergic P2 receptors in the regulation of cutaneous vasodilation in young adults at rest and during intermittent moderate-intensity exercise in the heat (35 °C). P2 receptor blockade augmented resting cutaneous vasodilation but had no influence during and following exercise. This increase was partly diminished by nitric oxide synthase inhibition. These results suggest a functional role of P2 receptors in the regulation of cutaneous vascular tone during ambient heat exposure at rest.
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Affiliation(s)
- Naoto Fujii
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,b Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Robert D Meade
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jeffrey C Louie
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Pegah Akbari
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Pierre Boulay
- c Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Ronald J Sigal
- d Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Glen P Kenny
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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Lang JA, Krajek AC, Smaller KA. Evidence for a functional vasoconstrictor role for ATP in the human cutaneous microvasculature. Exp Physiol 2017; 102:684-693. [PMID: 28295755 DOI: 10.1113/ep086231] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/06/2017] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? In young adults, about half of the cold-related reduction in skin blood flow during cold exposure is mediated by noradrenaline, while the remainder is attributable to other substances co-released with noradrenaline that have yet to be identified. What is the main finding and its importance? Purinergic receptor blockade blunted the vasoconstriction response to whole-body cooling and to intradermal administration of tyramine. These results indicate that ATP is necessary to vasoconstrict blood vessels in the skin adequately and prevent heat loss in a cold environment. Noradrenaline is responsible for eliciting ∼60% of the reflex cutaneous vasoconstriction (VC) response in young adults, while the remainder is attributable to one or more unidentified co-released sympathetic adrenergic neurotransmitter(s). Inconsistent evidence has placed neuropeptide Y in this role; however, other putative cotransmitters have yet to be tested. We hypothesize that ATP contributes to the reflex cutaneous VC response. Two protocols were conducted in young adults (n = 10); both involved the placement of three microdialysis probes in forearm skin and whole-body cooling (skin temperature = 30.5°C). In protocol 1, the following solutions were infused: (i) lactated Ringer solution (control); (ii) 10 mm l-NAME; and (iii) purinergic receptor blockade with 1 mm suramin plus l-NAME. In protocol 2, the following solutions were infused: (i) lactated Ringer solution; (ii) suramin plus l-NAME; and (iii) suramin plus l-NAME plus adrenoreceptor blockade with 5 mm yohimbine plus 1 mm propranolol. Laser Doppler flux (LDF) was measured over each microdialysis site, and cutaneous vascular conductance (CVC) was calculated (CVC = LDF/MAP) and expressed as percentage changes from baseline (%ΔCVCBASELINE ). l-NAME was used to block the vasodilatory influence of ATP and unmask the P2 X-mediated VC response to exogenous ATP infusion (-21 ± 6%ΔCVCBASELINE ). During cooling, the VC response (control, -39 ± 8%ΔCVCBASELINE ) was attenuated at the suramin site (-21 ± 4%ΔCVCBASELINE ) and further blunted with combined adrenoreceptor blockade (-9 ± 3%ΔCVCBASELINE ; P < 0.05). Compared with the control site (-22 ± 5%ΔCVCBASELINE ), suramin inhibited pharmacologically induced VC to tyramine (-12 ± 6%ΔCVCBASELINE ; P < 0.05), which displaces adrenergic neurotransmitters from axon terminals. These data indicate that ATP contributes to the cutaneous VC response in humans.
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Affiliation(s)
- James A Lang
- Department of Physical Therapy, Des Moines University, Des Moines, IA, USA
| | - Alex C Krajek
- Department of Physical Therapy, Des Moines University, Des Moines, IA, USA
| | - Kevin A Smaller
- Department of Neuroscience, Drake University, Des Moines, IA, USA
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Fujii N, McNeely BD, Nishiyasu T, Kenny GP. Prostacyclin does not affect sweating but induces skin vasodilatation to a greater extent in older versus younger women: roles of NO and K Ca channels. Exp Physiol 2017; 102:578-586. [PMID: 28271565 DOI: 10.1113/ep086297] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/02/2017] [Indexed: 01/03/2023]
Abstract
NEW FINDINGS What is the central question of this study? It remains unknown whether ageing modulates prostacyclin-induced cutaneous vasodilatation in women. What is the main finding and its importance? Prostacyclin induced cutaneous vasodilatation, albeit the magnitude of increase at lower concentrations of prostacyclin was greater in older relative to young women. This response was associated with greater contributions of nitric oxide synthase and calcium-activated potassium channels. Our results suggest that administration of prostacyclin might be an effective therapy to reverse microvascular hypoperfusion, especially in older women. We previously reported that prostacyclin induces cutaneous vasodilatation but not sweating in younger and older men. Furthermore, we demonstrated that nitric oxide synthase and calcium-activated potassium (KCa ) channels contribute to the prostacyclin-induced cutaneous vasodilatation in younger men, although these contributions are diminished in older men. Given that the effects of ageing might differ between men and women, the above results cannot simply be applied to women. In this study, cutaneous vascular conductance and sweat rate were evaluated in younger (mean ± SD, 22 ± 3 years old) and older (55 ± 7 years old) women (10 per group) at four intradermal forearm skin sites treated as follows: (i) lactated Ringer solution without any drug (control); (ii) 10 mm NG -nitro-l-arginine (l-NNA), a non-specific nitric oxide synthase inhibitor; (iii) 50 mm tetraethylammonium (TEA), a non-specific KCa channel blocker; or (iv) 10 mm l-NNA plus 50 mm TEA. All four sites were co-administered with prostacyclin in an incremental manner (0.04, 0.4, 4, 40 and 400 μm, each for 25 min). Surprisingly, increases in cutaneous vascular conductance in response to 0.04-4 μm prostacyclin were greater in older relative to younger women (all P ≤ 0.05), and these age-related differences were diminished when both l-NNA and TEA were administered simultaneously (all P > 0.05). No effect on sweat rate was observed in either group (all concentrations, P > 0.05). We show that although prostacyclin does not mediate sweating, it induces cutaneous vasodilatation, and this response elicited by lower concentrations of prostacyclin is greater in older relative to younger women. This greater cutaneous vasodilatation in older women is likely to be attributable to nitric oxide synthase- and KCa channel-dependent mechanisms.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Brendan D McNeely
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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González-Alonso J, Kalsi KK. The ubiquitous ATP molecule: could it be the elusive thermal mediator igniting skin perfusion and sweating in the heat-stressed human? J Physiol 2016; 593:2399. [PMID: 26033274 DOI: 10.1113/jp270558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 03/27/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- José González-Alonso
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, UK
| | - Kameljit K Kalsi
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, UK.,Institute of Infection and Immunity, St George's University of London, London, UK
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Fujii N, Halili L, Singh MS, Meade RD, Kenny GP. Intradermal administration of ATP augments methacholine-induced cutaneous vasodilation but not sweating in young males and females. Am J Physiol Regul Integr Comp Physiol 2015; 309:R912-9. [PMID: 26290105 DOI: 10.1152/ajpregu.00261.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/10/2015] [Indexed: 12/14/2022]
Abstract
Acetylcholine released from cholinergic nerves is a key neurotransmitter contributing to heat stress-induced cutaneous vasodilation and sweating. Given that sympathetic cholinergic nerves also release ATP, ATP may play an important role in modulating cholinergic cutaneous vasodilation and sweating. However, the pattern of response may differ between males and females given reports of sex-related differences in the peripheral mechanisms governing these heat loss responses. Cutaneous vascular conductance (CVC, laser-Doppler perfusion units/mean arterial pressure) and sweat rate (ventilated capsule) were evaluated in 17 young adults (8 males, 9 females) at four intradermal microdialysis skin sites continuously perfused with: 1) lactated Ringer (Control), 2) 0.3 mM ATP, 3) 3 mM ATP, or 4) 30 mM ATP. At all skin sites, methacholine was coadministered in a concentration-dependent manner (0.0125, 0.25, 5, 100, 2,000 mM, each for 25 min). In both males and females, CVC was elevated with the lone infusion of 30 mM ATP (both P < 0.05), but not with 0.3 and 3 mM ATP compared with control (all P >0.27). However, 0.3 mM ATP induced a greater increase in CVC compared with control in response to 100 mM methacholine infusion in males (P < 0.05). In females, 0.3 mM ATP infusion resulted in a lower concentration of methacholine required to elicit a half-maximal response (EC50) (P < 0.05). In both males and females, methacholine-induced sweating was unaffected by any concentration of ATP (all P > 0.44). We demonstrate that ATP enhances cholinergic cutaneous vasodilation albeit the pattern of response differs between males and females. Furthermore, we show that ATP does not modulate cholinergic sweating.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Lyra Halili
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Maya Sarah Singh
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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Fujii N, McGinn R, Halili L, Singh MS, Kondo N, Kenny GP. Cutaneous vascular and sweating responses to intradermal administration of ATP: a role for nitric oxide synthase and cyclooxygenase? J Physiol 2015; 593:2515-25. [PMID: 25809194 DOI: 10.1113/jp270147] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/13/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In humans in vivo, the mechanisms behind ATP-mediated cutaneous vasodilatation along with whether and how ATP increases sweating remains uncertain. Recent work has implicated nitric oxide synthase (NOS), cyclooxygenase (COX) and/or adenosine in the modulation of cutaneous vasodilatation and sweat production during both local (i.e. localized heating) and whole-body heat stress (i.e. exercise-induced heat stress). We evaluated whether ATP-mediated cutaneous vasodilatation and sweating is mediated via NOS, COX and/or adenosine. We show that in humans in vivo, intradermal administration of ATP induces pronounced vasodilatation which is partially mediated by NOS, but neither COX nor adenosine influences ATP-mediated vasodilatation, and ATP alone does not induce an increase in sweating. These findings advance our basic physiological knowledge regarding control of skin blood flow and sweating, and provide insight into the mechanisms governing thermoeffector activity, which has major implications for whole-body heat exchange and therefore core temperature regulation in humans during heat stress. ABSTRACT In humans in vivo, the mechanisms behind ATP-mediated cutaneous vasodilatation and whether and how ATP increases sweating remain uncertain. We evaluated whether ATP-mediated cutaneous vasodilatation and sweating is mediated via nitric oxide synthase (NOS), cyclooxygenase (COX) and/or adenosine-dependent mechanisms. Cutaneous vascular conductance (CVC, laser Doppler perfusion units/mean arterial pressure) and sweat rate (ventilated capsule) were evaluated at intradermal microdialysis forearm skin sites, each receiving pharmacological agents (two separate protocols). In Protocol 1 (n = 12), sites were perfused with: (1) lactated Ringer solution (Control), (2) 10 mm N(ω) -nitro-l-arginine (l-NNA, a NOS inhibitor), (3) 10 mm ketorolac (Ketorolac, a COX inhibitor) or (4) a combination of 10 mm l-NNA + 10 mm ketorolac (l-NNA + Ketorolac). In Protocol 2 (n = 8), sites were perfused with: (1) lactated Ringer solution (Control) or (2) 4 mm theophylline (Theophylline, an adenosine receptor inhibitor). At all sites, ATP was simultaneously perfused at 0.12, 1.2, 12, 120 and 1200 nm min(-1) (each for 20 min). Relative to CVC at the Control site with ATP infused at 120 nm min(-1) (71 ± 9% of max CVC), CVC at the Ketorolac site was comparable (64 ± 13% of max CVC, P = 0.407), but lower at l-NNA (51 ± 15% of max CVC, P = 0.040) and l-NNA + Ketorolac (51 ± 13% of max CVC, P = 0.049) sites. Conversely, across the four skin sites at any other ATP infusion rate (all P > 0.174), no differences in CVC were observed. Theophylline did not influence CVC at any ATP infusion rate (all P > 0.234). Furthermore, no ATP infusion rate elicited an increase in sweating from baseline at any skin site (all P > 0.235). We show that NOS, but neither COX nor adenosine receptors, modulates ATP-mediated cutaneous vasodilatation, whereas ATP does not directly increase sweating.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Lyra Halili
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Maya Sarah Singh
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Narihiko Kondo
- Faculty of Human Development, Kobe University, Kobe, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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Burnstock G, Ralevic V. Purinergic signaling and blood vessels in health and disease. Pharmacol Rev 2013; 66:102-92. [PMID: 24335194 DOI: 10.1124/pr.113.008029] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK; and Department of Pharmacology, The University of Melbourne, Australia.
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14
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Gifford JR, Heal C, Bridges J, Goldthorpe S, Mack GW. Changes in dermal interstitial ATP levels during local heating of human skin. J Physiol 2012; 590:6403-11. [PMID: 23045344 DOI: 10.1113/jphysiol.2012.240523] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Heating skin is believed to activate vanilloid type III and IV transient receptor potential ion channels (TRPV3, TRPV4, respectively), resulting in the release of ATP into the interstitial fluid. We examined the hypothesis that local skin heating would result in an accumulation of ATP in the interstitial fluid that would be related with a rise in skin blood flow (SkBF) and temperature sensation. Two microdialysis probes were inserted into the dermis on the dorsal aspect of the forearm in 15 young, healthy subjects. The probed skin was maintained at 31°C, 35°C, 39°C and 43°C for 8 min periods, during which SkBF was monitored as cutaneous vascular conductance (CVC). Dialysate was collected and analysed for ATP ([ATP](d)) using a luciferase-based assay, and ratings of perceived warmth were taken at each temperature. At a skin temperature of 31°C, [ATP](d) averaged 18.93 ± 4.06 nm and CVC averaged 12.57 ± 1.59% peak. Heating skin to 35°C resulted in an increase in CVC (17.63 ± 1.27% peak; P < 0.05), but no change in [ATP](d). Heating skin to 39°C and 43°C resulted in a decreased [ATP](d) (5.88 ± 1.68 nm and 8.75 ± 3.44 nm, respectively; P < 0.05), which was accompanied by significant elevations in CVC (38.90 ± 1.37% peak and 60.32 ± 1.95% peak, respectively; P < 0.05). Ratings of perceived warmth increased in proportion to the increase in skin temperature (r(2) = 0.75, P < 0.05). In conclusion, our data indicate that an accumulation of interstitial ATP does not occur during local heating, and therefore does not have a role in temperature sensation or the dilator response in human skin. Nevertheless, the low threshold of dilatation (35°C) indicates a possible role for the TRPV3, TRPV4 channels or the sensitization of other ion channels in mediating the dilator response.
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Affiliation(s)
- Jayson R Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, UT, USA.
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15
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Fieger SM, Wong BJ. No direct role for A1/A2 adenosine receptor activation to reflex cutaneous vasodilatation during whole-body heat stress in humans. Acta Physiol (Oxf) 2012; 205:403-10. [PMID: 22356216 DOI: 10.1111/j.1748-1716.2012.02426.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 10/26/2011] [Accepted: 02/09/2012] [Indexed: 11/29/2022]
Abstract
AIM The precise mechanisms underlying reflex cutaneous vasodilatation during hyperthermia remain unresolved. The purpose of this study was to investigate a potential contribution of adenosine A1/A2 receptor activation to reflex cutaneous vasodilatation. METHODS Eight subjects were equipped with four microdialysis fibres on the left forearm, and each fibre was randomly assigned one of four treatments: (1) lactated Ringer's (control); (2) 4 mm of the non-selective A1/A2 adenosine receptor antagonist theophylline; (3) 10 mm L-NAME to inhibit nitric oxide (NO) synthase; and (4) combined 4 mm theophylline and 10 mm L-NAME. Laser-Doppler flowmetry (LDF) was used as an index of skin blood flow, and blood pressure was measured beat-by-beat via photoplethysmography and verified via brachial auscultation. Whole-body heat stress to raise oral temperature 0.8 °C above baseline was induced via water-perused suits. Cutaneous vascular conductance (CVC) was calculated as LDF/mean arterial pressure and normalized to maximal (%CVC max) via infusion of 28 mm nitroprusside and local heating to 43 °C. RESULTS There was no difference between control (65 ± 5%CVC max) and theophylline (63 ± 5%CVC max) sites. L-NAME (44 ± 4%CVC max) and theophylline + L-NAME (32 ± 3%CVC max) sites were significantly attenuated compared to both control and theophylline only sites (P<0.05), and combined theophylline + L-NAME sites were significantly reduced compared to L-NAME only sites (P<0.05). CONCLUSION These data suggest A1/A2 adenosine receptor activation does not directly contribute to cutaneous active vasodilatation; however, a role for A1/A2 adenosine receptor activation is unmasked when NO synthase is inhibited.
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Affiliation(s)
- S. M. Fieger
- Department of Kinesiology; Kansas State University; Manhattan; KS; USA
| | - B. J. Wong
- Department of Kinesiology; Kansas State University; Manhattan; KS; USA
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Mahé G, Rousseau P, Durand S, Bricq S, Leftheriotis G, Abraham P. Laser speckle contrast imaging accurately measures blood flow over moving skin surfaces. Microvasc Res 2010; 81:183-8. [PMID: 21156183 DOI: 10.1016/j.mvr.2010.11.013] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 11/29/2010] [Accepted: 11/30/2010] [Indexed: 12/01/2022]
Abstract
Cutaneous blood flow (CBF) can be assessed non-invasively with lasers. Unfortunately, movement artefacts in the laser skin signal (LS(sk)) might sometimes compromise the interpretation of the data. To date, no method is available to remove movement artefacts point-by-point. Using a laser speckle contrast imager, we simultaneously recorded LS(sk) and the signal backscattered from an adjacent opaque surface (LS(os)). The completion of a first protocol allowed a definition of a simple equation to calculate the CBF from movement artefact-affected traces of LS(sk) and LS(os). We then recorded LS(sk) and LS(os) before, during and for 5 min after the tourniquet ischemia, both when subjects (n=8) were immobile or submitted to external passive movements of random intensity throughout the test. The typical post-occlusive reactive hyperemia trace was not identifiable within the LS(sk) recordings, with LS(sk) being 2 to 3 times higher during movements than in the immobile situation. After the calculation of CBF, traces in the immobile versus movement conditions were comparable, with the "r" cross-correlation coefficient being 0.930+/-0.010. Our method might facilitate future investigations in microvascular physiology and pathophysiology, specifically in subjects who have frequent or continuous involuntary movements.
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Affiliation(s)
- Guillaume Mahé
- Laboratory of Vascular Investigations, University Hospital of Angers, France
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