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Clough GF, Kuliga KZ, Chipperfield AJ. Flow motion dynamics of microvascular blood flow and oxygenation: Evidence of adaptive changes in obesity and type 2 diabetes mellitus/insulin resistance. Microcirculation 2018; 24. [PMID: 27809397 DOI: 10.1111/micc.12331] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/31/2016] [Indexed: 11/29/2022]
Abstract
An altered spatial heterogeneity and temporal stability of network perfusion can give rise to a limited adaptive ability to meet metabolic demands. Derangement of local flow motion activity is associated with reduced microvascular blood flow and tissue oxygenation, and it has been suggested that changes in flow motion activity may provide an early indicator of declining, endothelial, neurogenic, and myogenic regulatory mechanisms and signal the onset and progression of microvascular pathophysiology. This short conference review article explores some of the evidence for altered flow motion dynamics of blood flux signals acquired using laser Doppler fluximetry in the skin in individuals at risk of developing or with cardiometabolic disease.
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Affiliation(s)
| | - Katarzyna Z Kuliga
- Faculty of Medicine, University of Southampton, Southampton, UK.,Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - Andrew J Chipperfield
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
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Hurr C, Patik JC, Kim K, Christmas KM, Brothers RM. Tempol augments the blunted cutaneous microvascular thermal reactivity in healthy young African Americans. Exp Physiol 2018; 103:343-349. [PMID: 29271085 DOI: 10.1113/ep086776] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 12/18/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? The purpose was to determine whether there is a difference between African Americans and Caucasians in cutaneous microvascular function and whether this difference is attributable to elevated oxidative stress. What is the main finding and its importance? The main finding is that African Americans have an attenuated cutaneous vasodilatation during local heating relative to Caucasians that is restored with local infusion of the superoxide dismutase mimetic, tempol. This suggests that superoxide mediates microvascular dysfunction and might contribute to the greater prevalence of cardiovascular disease in this population. ABSTRACT African Americans (AA) have elevated risk for cardiovascular disease relative to other populations. We hypothesized that the cutaneous hyperaemic response to local heating is reduced in young AA relative to Caucasian Americans (CA) and that this is attributable to elevated oxidative stress. As such, ascorbic acid (a global antioxidant) and tempol (a superoxide dismutase mimetic) would improve this response in AA. Microdialysis fibres received lactated Ringer solution (control), 10 mm ascorbic acid or 10 μm 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol) at a rate of 2.0 μl min-1 . Cutaneous vascular conductance (CVC) was calculated as the red blood cell flux divided by mean arterial pressure. Data were presented as a percentage of maximal CVC (%CVCmax ) induced by 44°C heating plus sodium nitroprusside. Twenty-four (12 AA, 12 CA) young (23 ± 4 years old) subjects participated. During 39°C heating, the %CVCmax was lower in AA at the control (CA, 65 ± 20% versus AA, 47 ± 15%; P < 0.05) and ascorbic acid sites (CA, 73 ± 14% versus AA: 49 ± 17%; P < 0.01). At the tempol site, there were no differences between groups. This was followed by infusion of 10 mm l-NAME at all sites to assess the contribution of nitric oxide to vasodilatation during local heating. The contribution of nitric oxide was lower in AA relative to CA at 39°C; however, this was restored with tempol. These data suggest that: (i) cutaneous vasodilatation in response to local heating is blunted in AA relative to CA; and (ii) elevated superoxide generation attenuates nitric oxide-mediated cutaneous vasodilatation in AA.
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Affiliation(s)
- Chansol Hurr
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.,Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA
| | - Jordan C Patik
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.,Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, USA
| | - KiYoung Kim
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.,Department of Pathology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kevin M Christmas
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.,Department of Bioengineering, The University of Washington, Seattle, WA, USA
| | - R Matthew Brothers
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.,Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, USA
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54
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Fujii N, Halili L, Nishiyasu T, Kenny GP. Voltage-gated potassium channels and NOS contribute to a sustained cutaneous vasodilation elicited by local heating in an interactive manner in young adults. Microvasc Res 2017; 117:22-27. [PMID: 29247720 DOI: 10.1016/j.mvr.2017.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 12/13/2022]
Abstract
Local skin heating to 42°C causes rapid increases in cutaneous perfusion (initial peak), followed by a brief nadir and subsequent sustained elevation (plateau). Several studies have demonstrated that nitric oxide synthase (NOS) largely contributes to the plateau response during local heating. In this study, we tested the hypothesis that voltage-gated potassium (Kv) channels contribute to the plateau of the cutaneous vasodilation during local heating through NOS-dependent mechanisms. Eleven young males (25±4years) participated in this study wherein cutaneous vascular conductance (CVC) was measured at four intradermal microdialysis sites that were continuously perfused with either 1) lactated Ringer (Control), 2) 10mM 4-aminopyridine (Kv channel blocker), 3) 10mM Nω-Nitro-L-arginine (NOS inhibitor), or 4) a combination of 4-aminopyridine and Nω-Nitro-L-arginine. In comparison to the Control site, the inhibition of Kv channels alone attenuated the increase in CVC observed at the initial peak, nadir, and plateau phases measured during local heating; in contrast, the inhibition of NOS alone attenuated the increase in CVC at the nadir and plateau phases only (e.g., plateau response: Control site: 59±5%max, Kv channel blockade site: 49±8%max, NOS inhibition site: 35±11%max, combined inhibition site: 40±12%max). Further, no effect of Kv channel blockade on CVC was measured at any phase of the local heating response when the modulating influence of NOS was simultaneously removed. We show that Kv channels and NOS contribute to the local heating mediated sustained increase (i.e., plateau) in cutaneous vasodilation in an interactive manner. (243/250 words).
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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 City, Japan
| | - Lyra Halili
- 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
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
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Therapeutic potential of omega-3 fatty acid-derived epoxyeicosanoids in cardiovascular and inflammatory diseases. Pharmacol Ther 2017; 183:177-204. [PMID: 29080699 DOI: 10.1016/j.pharmthera.2017.10.016] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Numerous benefits have been attributed to dietary long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs), including protection against cardiac arrhythmia, triglyceride-lowering, amelioration of inflammatory, and neurodegenerative disorders. This review covers recent findings indicating that a variety of these beneficial effects are mediated by "omega-3 epoxyeicosanoids", a class of novel n-3 LC-PUFA-derived lipid mediators, which are generated via the cytochrome P450 (CYP) epoxygenase pathway. CYP enzymes, previously identified as arachidonic acid (20:4n-6; AA) epoxygenases, accept eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), the major fish oil n-3 LC-PUFAs, as efficient alternative substrates. In humans and rodents, dietary EPA/DHA supplementation causes a profound shift of the endogenous CYP-eicosanoid profile from AA- to EPA- and DHA-derived metabolites, increasing, in particular, the plasma and tissue levels of 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP). Based on preclinical studies, these omega-3 epoxyeicosanoids display cardioprotective, vasodilatory, anti-inflammatory, and anti-allergic properties that contribute to the beneficial effects of n-3 LC-PUFAs in diverse disease conditions ranging from cardiac disease, bronchial disorders, and intraocular neovascularization, to allergic intestinal inflammation and inflammatory pain. Increasing evidence also suggests that background nutrition as well as genetic and disease state-related factors could limit the response to EPA/DHA-supplementation by reducing the formation and/or enhancing the degradation of omega-3 epoxyeicosanoids. Recently, metabolically robust synthetic analogs mimicking the biological activities of 17,18-EEQ have been developed. These drug candidates may overcome limitations of dietary EPA/DHA supplementation and provide novel options for the treatment of cardiovascular and inflammatory diseases.
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Louie JC, Fujii N, Meade RD, Kenny GP. The roles of the Na+/K+-ATPase, NKCC, and K+ channels in regulating local sweating and cutaneous blood flow during exercise in humans in vivo. Physiol Rep 2017; 4:4/22/e13024. [PMID: 27881572 PMCID: PMC5358008 DOI: 10.14814/phy2.13024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 10/05/2016] [Indexed: 11/24/2022] Open
Abstract
Na+/K+‐ATPase has been shown to regulate the sweating and cutaneous vascular responses during exercise; however, similar studies have not been conducted to assess the roles of the Na‐K‐2Cl co‐transporter (NKCC) and K+ channels. Additionally, it remains to be determined if these mechanisms underpinning the heat loss responses differ with exercise intensity. Eleven young (24 ± 4 years) males performed three 30‐min semirecumbent cycling bouts at low (30% VO2peak), moderate (50% VO2peak), and high (70% VO2peak) intensity, respectively, each separated by 20‐min recovery periods. Using intradermal microdialysis, four forearm skin sites were continuously perfused with either: (1) lactated Ringer solution (Control); (2) 6 mmol·L−1 ouabain (Na+/K+‐ATPase inhibitor); (3) 10 mmol·L−1 bumetanide (NKCC inhibitor); or (4) 50 mmol·L−1 BaCl2 (nonspecific K+ channel inhibitor); sites at which we assessed local sweat rate (LSR) and cutaneous vascular conductance (CVC). Inhibition of Na+/K+‐ATPase attenuated LSR compared to Control during the moderate and high‐intensity exercise bouts (both P ˂ 0.01), whereas attenuations with NKCC and K+ channel inhibition were only apparent during the high‐intensity exercise bout (both P ≤ 0.05). Na+/K+‐ATPase inhibition augmented CVC during all exercise intensities (all P ˂ 0.01), whereas CVC was greater with NKCC inhibition during the low‐intensity exercise only (P ˂ 0.01) and attenuated with K+ channel inhibition during the moderate and high‐intensity exercise conditions (both P ˂ 0.01). We show that Na+/K+‐ATPase, NKCC and K+ channels all contribute to the regulation of sweating and cutaneous blood flow but their influence is dependent on the intensity of dynamic exercise.
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Affiliation(s)
- Jeffrey C Louie
- 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
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
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Agra KF, Pontes IEA, da Silva JR, Figueiroa JN, Clough GF, Alves JGB. Impaired neurovascular reactivity in the microvasculature of pregnant women with preeclampsia. Microcirculation 2017; 24. [DOI: 10.1111/micc.12383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 05/08/2017] [Indexed: 01/24/2023]
Affiliation(s)
- Karine Ferreira Agra
- Department of Mother and Child Health; Instituto de Medicina Integral Prof. Fernando Figueira-IMIP; Recife Brazil
| | | | - José Roberto da Silva
- Department of Mother and Child Health; Instituto de Medicina Integral Prof. Fernando Figueira-IMIP; Recife Brazil
| | - José Natal Figueiroa
- Department of Mother and Child Health; Instituto de Medicina Integral Prof. Fernando Figueira-IMIP; Recife Brazil
| | | | - João Guilherme Bezerra Alves
- Department of Mother and Child Health; Instituto de Medicina Integral Prof. Fernando Figueira-IMIP; Recife Brazil
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The role of shear stress on cutaneous microvascular endothelial function in humans. Eur J Appl Physiol 2017; 117:2457-2468. [PMID: 28986690 DOI: 10.1007/s00421-017-3732-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/30/2017] [Indexed: 12/31/2022]
Abstract
PURPOSE Previous studies suggest that exercise and heat stress improve cutaneous endothelial function, caused by increases in shear stress. However, as vasodilatation in the skin is primarily a thermogenic phenomenon, we investigated if shear stress alone without increases in skin temperature that occur with exercise and heat stress increases endothelial function. We examined the hypothesis that repeated bouts of brief occlusion would improve cutaneous endothelial function via shear stress-dependent mechanisms. METHODS Eleven males underwent a shear stress intervention (forearm occlusion 5 s rest 10 s) for 30 min, five times·week-1 for 6 weeks on one arm, the other was an untreated control. Skin blood flow was measured using laser-Doppler flowmetry, and endothelial function was assessed with and without NOS-inhibition with L-NAME in response to three levels of local heating (39, 42, and 44 °C), ACh administration, and reactive hyperaemia. Data are cutaneous vascular conductance (CVC, laser-Doppler/blood pressure). RESULTS There were no changes in the control arm (all d ≤ 0.2, p > 0.05). In the experimental arm, CVC to 39 °C was increased after 3 and 6 weeks (d = 0.6; p ≤ 0.01). Nitric oxide contribution was increased after 6 weeks compared to baseline (d = 0.85, p < 0.001). Following skin heating to 42 °C and 44 °C, CVC was not different at weeks 3 or 6 (d ≤ 0.8, p > 0.05). For both 42 and 44 °C, nitric oxide contribution was increased after weeks 3 and 6 (d ≥ 0.4, p < 0.03). Peak and area-under-the-curve responses to ACh increased following 6 weeks (p < 0.001). CONCLUSIONS Episodic increases in shear stress, without changes in skin or core temperature, elicit an increase in cutaneous microvascular reactivity and endothelial function.
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Fujii N, Zhang SY, McNeely BD, Nishiyasu T, Kenny GP. Heat shock protein 90 contributes to cutaneous vasodilation through activating nitric oxide synthase in young male adults exercising in the heat. J Appl Physiol (1985) 2017; 123:844-850. [PMID: 28751373 PMCID: PMC5668448 DOI: 10.1152/japplphysiol.00446.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/25/2017] [Accepted: 07/25/2017] [Indexed: 12/25/2022] Open
Abstract
While the mechanisms underlying the control of cutaneous vasodilation have been extensively studied, there remains a lack of understanding of the different factors that may modulate cutaneous perfusion during an exercise-induced heat stress. We evaluated the hypothesis that heat shock protein 90 (HSP90) contributes to the heat loss response of cutaneous vasodilation via the activation of nitric oxide synthase (NOS) during exercise in the heat. In 11 young males (25 ± 5 yr), cutaneous vascular conductance (CVC) was measured at four forearm skin sites that were continuously treated with 1) lactated Ringer solution (control), 2) NOS inhibition with 10 mM NG-nitro-l-arginine methyl ester (l-NAME), 3) HSP90 inhibition with 178 μM geldanamycin, or 4) a combination of 10 mM l-NAME and 178 μM geldanamycin. Participants rested in a moderate heat stress (35°C) condition for 70 min. Thereafter, they performed a 50-min bout of moderate-intensity cycling (~52% V̇o2peak) followed by a 30-min recovery period. We showed that NOS inhibition attenuated CVC (~40-50%) relative to the control site during pre- and postexercise rest in the heat (P ≤ 0.05); however, no effect of HSP90 inhibition was observed (P > 0.05). During exercise, we observed an attenuation of CVC with the separate inhibition of NOS (~40-50%) and HSP90 (~15-20%) compared with control (both P ≤ 0.05). However, the effect of HSP90 inhibition was absent in the presence of the coinhibition of NOS (P > 0.05). We show that HSP90 contributes to cutaneous vasodilation in young men exposed to the heat albeit during exercise only. We also show that the HSP90 contribution is due to NOS-dependent mechanisms.NEW & NOTEWORTHY We show that heat shock protein 90 functionally contributes to the heat loss response of cutaneous vasodilation during exercise in the heat, and this response is mediated through the activation of nitric oxide synthase. Therefore, interventions that may activate heat shock protein 90 may facilitate an increase in heat dissipation through an augmentation of cutaneous perfusion. In turn, this may attenuate or reduce the increase in core temperature and therefore the level of heat strain.
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Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sports Science, University of Tsukuba, Tsukuba, Japan; and
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Sarah Y Zhang
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Brendan D McNeely
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sports Science, University of Tsukuba, Tsukuba, Japan; and
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
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Smith CJ, Craighead DH, Alexander LM. Effects of vehicle microdialysis solutions on cutaneous vascular responses to local heating. J Appl Physiol (1985) 2017; 123:1461-1467. [PMID: 28860170 DOI: 10.1152/japplphysiol.00498.2017] [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] [Indexed: 12/23/2022] Open
Abstract
Microdialysis is a minimally invasive technique often paired with laser Doppler flowmetry to examine cutaneous microvascular function, yet presents with several challenges, including incompatibility with perfusion of highly lipophilic compounds. The present study addresses this methodological concern, with an emphasis on the independent effects of commonly used vehicle dialysis solutions to improve solubility of pharmacological agents with otherwise low aqueous solubility. Four microdialysis fibers were placed in the ventral forearm of eight subjects (4 men, 4 women; 25 ± 1 yr) with sites randomized to serve as 1) control (lactated Ringer's), 2) Sodium carbonate-bicarbonate buffer administered at physiological pH [SCB-HCl; pH 7.4, achieved via addition of hydrochloric acid (HCl)], 3) 0.02% ethanol, and 4) 2% dimethyl sulfoxide (DMSO). After baseline (34°C), vehicle solutions were administered throughout a standardized local heating protocol to 42°C. Laser Doppler flowmetry provided an index of blood flow. Cutaneous vascular conductance was calculated and normalized to maximum (%CVCmax, sodium nitroprusside and 43°C local heat). The SCB-HCl solution increased baseline %CVCmax (control: 9.7 ± 0.8; SCB-HCl: 21.5 ± 3.5%CVCmax; P = 0.03), but no effects were observed during heating or maximal vasodilation. There were no differences with perfusion of ethanol or DMSO at any stage of the protocol ( P > 0.05). These data demonstrate the potential confounding effects of some vehicle dialysis solutions on cutaneous vascular function. Notably, this study provides evidence that 2% DMSO and 0.02% ethanol are acceptable vehicles with no confounding local vascular effects to a standardized local heating protocol at the concentrations presented. NEW & NOTEWORTHY This study examined the independent effects of common vehicle solutions on cutaneous vascular responses. A basic buffer (SCB-HCl) caused baseline vasodilation; 2% DMSO and 0.02% ethanol had no effects. This highlights the need for considering potential confounding effects of solubilizing solutions when combined with low aqueous soluble pharmacological agents. Importantly, DMSO and ethanol do not appear to influence cutaneous vascular function during baseline or local heating at the concentrations studied, allowing their use without confounding effects.
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Affiliation(s)
- Caroline J Smith
- Department of Health and Exercise Science, Appalachian State University, Boone, North Carolina
| | - Daniel H Craighead
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University , University Park, Pennsylvania
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University , University Park, Pennsylvania
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Hodges GJ, Mallette MM, Tew GA, Saxton JM, Moss J, Ruddock AD, Klonizakis M. Effect of age on cutaneous vasomotor responses during local skin heating. Microvasc Res 2017; 112:47-52. [DOI: 10.1016/j.mvr.2017.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 12/19/2022]
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Jonasson H, Bergstrand S, Nystrom FH, Länne T, Östgren CJ, Bjarnegård N, Fredriksson I, Larsson M, Strömberg T. Skin microvascular endothelial dysfunction is associated with type 2 diabetes independently of microalbuminuria and arterial stiffness. Diab Vasc Dis Res 2017; 14:363-371. [PMID: 28482676 DOI: 10.1177/1479164117707706] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Skin and kidney microvascular functions may be affected independently in diabetes mellitus. We investigated skin microcirculatory function in 79 subjects with diabetes type 2, where 41 had microalbuminuria and 38 not, and in 41 age-matched controls. The oxygen saturation, fraction of red blood cells and speed-resolved microcirculatory perfusion (% red blood cells × mm/s) divided into three speed regions: 0-1, 1-10 and above 10 mm/s, were assessed during baseline and after local heating of the foot with a new device integrating diffuse reflectance spectroscopy and laser Doppler flowmetry. Arterial stiffness was assessed as carotid-femoral pulse wave velocity. Subjects with diabetes and microalbuminuria had significantly higher carotid-femoral pulse wave velocity compared to subjects without microalbuminuria and to controls. The perfusion for speeds 0-1 mm/s and red blood cell tissue fraction were reduced in subjects with diabetes at baseline and after heating, independent of microalbuminuria. These parameters were correlated to HbA1c. In conclusion, the reduced nutritive perfusion and red blood cell tissue fraction in type 2 diabetes were related to long-term glucose control but independent of microvascular changes in the kidneys and large-vessel stiffness. This may be due to different pathogenic pathways in the development of nephropathy, large-vessel stiffness and cutaneous microvascular impairment.
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Affiliation(s)
- Hanna Jonasson
- 1 Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Sara Bergstrand
- 1 Department of Biomedical Engineering, Linköping University, Linköping, Sweden
- 2 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Fredrik H Nystrom
- 2 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Toste Länne
- 2 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Carl Johan Östgren
- 2 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Niclas Bjarnegård
- 2 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Ingemar Fredriksson
- 1 Department of Biomedical Engineering, Linköping University, Linköping, Sweden
- 3 Perimed AB, Stockholm, Sweden
| | - Marcus Larsson
- 1 Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Tomas Strömberg
- 1 Department of Biomedical Engineering, Linköping University, Linköping, Sweden
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Francisco MA, Brunt VE, Jensen KN, Lorenzo S, Minson CT. Ten days of repeated local forearm heating does not affect cutaneous vascular function. J Appl Physiol (1985) 2017; 123:310-316. [PMID: 28473615 DOI: 10.1152/japplphysiol.00966.2016] [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: 11/01/2016] [Revised: 04/14/2017] [Accepted: 04/26/2017] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to determine whether 10 days of repeated local heating could induce peripheral adaptations in the cutaneous vasculature and to investigate potential mechanisms of adaptation. We also assessed maximal forearm blood flow to determine whether repeated local heating affects maximal dilator capacity. Before and after 10 days of heat training consisting of 1-h exposures of the forearm to 42°C water or 32°C water (control) in the contralateral arm (randomized and counterbalanced), we assessed hyperemia to rapid local heating of the skin (n = 14 recreationally active young subjects). In addition, sequential doses of acetylcholine (ACh, 1 and 10 mM) were infused in a subset of subjects (n = 7) via microdialysis to study potential nonthermal microvascular adaptations following 10 days of repeated forearm heat training. Skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as laser-Doppler red blood cell flux divided by mean arterial pressure. Maximal cutaneous vasodilation was achieved by heating the arm in a water-spray device for 45 min and assessed using venous occlusion plethysmography. Forearm vascular conductance (FVC) was calculated as forearm blood flow divided by mean arterial pressure. Repeated forearm heating did not increase plateau percent maximal CVC (CVCmax) responses to local heating (89 ± 3 vs. 89 ± 2% CVCmax, P = 0.19), 1 mM ACh (43 ± 9 vs. 53 ± 7% CVCmax, P = 0.76), or 10 mM ACh (61 ± 9 vs. 85 ± 7% CVCmax, P = 0.37, by 2-way repeated-measures ANOVA). There was a main effect of time at 10 mM ACh (P = 0.03). Maximal FVC remained unchanged (0.12 ± 0.02 vs. 0.14 ± 0.02 FVC, P = 0.30). No differences were observed in the control arm. Ten days of repeated forearm heating in recreationally active young adults did not improve the microvascular responsiveness to ACh or local heating.NEW & NOTEWORTHY We show for the first time that 10 days of repeated forearm heating is not sufficient to improve cutaneous vascular responsiveness in recreationally active young adults. In addition, this is the first study to investigate cutaneous cholinergic sensitivity and forearm blood flow following repeated local heat exposure. Our data add to the limited studies regarding repeated local heating of the cutaneous vasculature.
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Affiliation(s)
| | - Vienna E Brunt
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | | | - Santiago Lorenzo
- Lake Erie College of Osteopathic Medicine-Bradenton, Bradenton, Florida
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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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65
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Mallette MM, Hodges GJ, McGarr GW, Gabriel DA, Cheung SS. Spectral analysis of reflex cutaneous vasodilatation during passive heat stress. Microvasc Res 2017; 111:42-48. [PMID: 28065673 DOI: 10.1016/j.mvr.2016.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/21/2016] [Accepted: 12/21/2016] [Indexed: 11/19/2022]
Abstract
Previous work has demonstrated that spectral analysis is a useful tool to non-invasively ascertain the mechanisms of control of the cutaneous circulation. The majority of work using spectral analysis has focused on local control mechanisms, with none examining reflex control. Skin blood flow was analysed using spectral analysis on the dorsal aspect of the forearm of 7 males and 7 females during passive heat stress, with mean forearm and local temperature at the site of measurement maintained at thermoneutral (33°C) to minimize the effect of local control mechanisms. Participants were passively heated to ~1.2±0.1°C above baseline rectal temperature (d=4.0, P<0.001) using a water-perfused, tube lined suit, with skin blood flow assessed using a laser-Doppler probe with an integrated temperature monitor. Spectral analysis was performed using a Morlet wavelet on the entire data set, with median power extracted during 20min of data during baseline (normothermia) and hyperthermia. Passive heat stress significantly increased laser-Doppler flux above baseline (d=4.7, P<0.001). Spectral power of the endothelial nitric oxide-independent (0.005-0.01Hz; d=1.1, P=0.004), neurogenic (0.2-0.05Hz; d=0.6, P=0.025), myogenic (0.05-0.15Hz; d=1.5, P=0.002), respiratory (0.15-0.4Hz; d=1.4 P=0.002), and cardiac (0.4-2.0Hz; d=1.1, P=0.012) frequency intervals increased with passive heat stress. In contrast, the endothelial nitric oxide-dependent frequency interval did not change (0.01-0.02Hz; d=0.3, P=0.09) with passive heat stress. These data suggest that cutaneous reflex vasodilatation is neurogenic in origin and not mediated by endothelial-nitric oxide synthase, and are congruent with invasive examinations of reflex cutaneous vasodilatation.
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Affiliation(s)
- Matthew M Mallette
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada
| | - Gary J Hodges
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada
| | - Gregory W McGarr
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada
| | - David A Gabriel
- Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada
| | - Stephen S Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Canada.
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66
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Kuliga KZ, Gush R, Clough GF, Chipperfield AJ. Time-dependent Behavior of Microvascular Blood Flow and Oxygenation: a Predictor of Functional Outcomes. IEEE Trans Biomed Eng 2017; 65:1049-1056. [DOI: 10.1109/tbme.2017.2737328] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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67
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Mechanisms and time course of menthol-induced cutaneous vasodilation. Microvasc Res 2016; 110:43-47. [PMID: 27899298 DOI: 10.1016/j.mvr.2016.11.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/20/2016] [Accepted: 11/22/2016] [Indexed: 11/23/2022]
Abstract
Menthol is a vasoactive compound that is widely used in topical analgesic agents. Menthol induces cutaneous vasodilation, however the underlying mechanisms are unknown. Determining the rates of appearance and clearance of menthol in the skin is important for optimizing topical treatment formulation and dosing. The purpose of this study was to determine the mechanisms contributing to menthol-mediated cutaneous vasodilation and to establish a time course for menthol appearance/clearance in the skin. Ten young (23±1years, 5 males 5 females) subjects participated in two protocols. In study 1, four intradermal microdialysis fibers were perfused with increasing doses of menthol (0.1-500mM) and inhibitors for nitric oxide (NO), endothelium derived hyperpolarizing factors (EDHFs), and sensory nerves. Skin blood flow was measured with laser Doppler flowmetry and normalized to %CVCmax. In study 2, two intradermal microdialysis fibers were perfused with lactated Ringer's solution. 0.017mL·cm-2 of a 4% menthol gel was placed over each fiber. 5μL samples of dialysate from the microdialysis fibers were collected every 30min and analyzed for the presence of menthol with high performance gas chromatography/mass spectrometry. Skin blood flow (laser speckle contrast imaging) and subjective ratings of menthol sensation were simultaneously obtained with dialysate samples. In study 1, menthol induced cutaneous vasodilation at all doses ≥100mM (all p<0.05). However, inhibition of either NO, EDHFs, or sensory nerves fully inhibited menthol-mediated vasodilation (all p>0.05). In study 2, significant menthol was detected in dialysate 30min post menthol application (0.89ng, p=0.0002). Relative to baseline, cutaneous vasodilation was elevated from minutes 15-45 and ratings of menthol sensation were elevated from minute 5-60 post menthol application (all p<0.05). Menthol induces cutaneous vasodilation in the skin through multiple vasodilator pathways, including NO, EDHF, and sensory nerves. Topical menthol is detectable in the skin within 30min and is cleared by 60min. Skin blood flow and perceptual measures follow a similar time course as menthol appearance/clearance.
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68
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Fujii N, Louie JC, McNeely BD, Zhang SY, Tran MA, Kenny GP. K+ channel mechanisms underlying cholinergic cutaneous vasodilation and sweating in young humans: roles of KCa, KATP, and KV channels? Am J Physiol Regul Integr Comp Physiol 2016; 311:R600-6. [PMID: 27440718 DOI: 10.1152/ajpregu.00249.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/14/2016] [Indexed: 11/22/2022]
Abstract
Acetylcholine released from cholinergic nerves is involved in heat loss responses of cutaneous vasodilation and sweating. K(+) channels are thought to play a role in regulating cholinergic cutaneous vasodilation and sweating, though which K(+) channels are involved in their regulation remains unclear. We evaluated the hypotheses that 1) Ca(2+)-activated K(+) (KCa), ATP-sensitive K(+) (KATP), and voltage-gated K(+) (KV) channels all contribute to cholinergic cutaneous vasodilation; and 2) KV channels, but not KCa and KATP channels, contribute to cholinergic sweating. In 13 young adults (24 ± 5 years), cutaneous vascular conductance (CVC) and sweat rate were evaluated at intradermal microdialysis sites that were continuously perfused with: 1) lactated Ringer (Control), 2) 50 mM tetraethylammonium (KCa channel blocker), 3) 5 mM glybenclamide (KATP channel blocker), and 4) 10 mM 4-aminopyridine (KV channel blocker). At all sites, cholinergic cutaneous vasodilation and sweating were induced by coadministration of methacholine (0.0125, 0.25, 5, 100, and 2,000 mM, each for 25 min). The methacholine-induced increase in CVC was lower with the KCa channel blocker relative to Control at 0.0125 (1 ± 1 vs. 9 ± 6%max) and 5 (2 ± 5 vs. 17 ± 14%max) mM methacholine, whereas it was lower in the presence of KATP (69 ± 7%max) and KV (57 ± 14%max) channel blocker compared with Control (79 ± 6%max) at 100 mM methacholine. Furthermore, methacholine-induced sweating was lower at the KV channel blocker site (0.42 ± 0.17 mg·min(-1)·cm(-2)) compared with Control (0.58 ± 0.15 mg·min(-1)·cm(-2)) at 2,000 mM methacholine. In conclusion, we show that KCa, KATP, and KV channels play a role in cholinergic cutaneous vasodilation, whereas only KV channels contribute to cholinergic sweating in normothermic resting humans.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Jeffrey C Louie
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Brendan D McNeely
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Sarah Yan Zhang
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - My-An Tran
- 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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Brunt VE, Eymann TM, Francisco MA, Howard MJ, Minson CT. Passive heat therapy improves cutaneous microvascular function in sedentary humans via improved nitric oxide-dependent dilation. J Appl Physiol (1985) 2016; 121:716-23. [PMID: 27418688 DOI: 10.1152/japplphysiol.00424.2016] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 07/11/2016] [Indexed: 11/22/2022] Open
Abstract
Passive heat therapy (repeated hot tub or sauna use) reduces cardiovascular risk, but its effects on the mechanisms underlying improvements in microvascular function have yet to be studied. We investigated the effects of heat therapy on microvascular function and whether improvements were related to changes in nitric oxide (NO) bioavailability using cutaneous microdialysis. Eighteen young, sedentary, otherwise healthy subjects participated in 8 wk of heat therapy (hot water immersion to maintain rectal temperature ≥38.5°C for 60 min/session; n = 9) or thermoneutral water immersion (sham, n = 9), and participated in experiments before and after the 8-wk intervention in which forearm cutaneous hyperemia to 39°C local heating was assessed at three microdialysis sites receiving 1) Lactated Ringer's (Control), 2) N(ω)-nitro-l-arginine (l-NNA; nonspecific NO synthase inhibitor), and 3) 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), a superoxide dismutase mimetic. The arm used for microdialysis experiments remained out of the water at all times. Data are means ± SE cutaneous vascular conductance (CVC = laser Doppler flux/mean arterial pressure), presented as percent maximal CVC (% CVCmax). Heat therapy increased local heating plateau from 42 ± 6 to 53 ± 6% CVCmax (P < 0.001) and increased NO-dependent dilation (difference in plateau between Control and l-NNA sites) from 26 ± 6 to 38 ± 4% CVCmax (P < 0.01), while no changes were observed in the sham group. When data were pooled across all subjects at 0 wk, Tempol had no effect on the local heating response (P = 0.53 vs. Control). There were no changes at the Tempol site across interventions (P = 0.58). Passive heat therapy improves cutaneous microvascular function by improving NO-dependent dilation, which may have clinical implications.
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Affiliation(s)
- Vienna E Brunt
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Taylor M Eymann
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | | | - Matthew J Howard
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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Cracowski JL, Roustit M. Current Methods to Assess Human Cutaneous Blood Flow: An Updated Focus on Laser-Based-Techniques. Microcirculation 2016; 23:337-44. [DOI: 10.1111/micc.12257] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/20/2015] [Indexed: 01/22/2023]
Affiliation(s)
- Jean-Luc Cracowski
- Université Grenoble Alpes; Grenoble France
- INSERM; Grenoble France
- Clinical Pharmacology Unit; INSERM CIC1406; Grenoble University Hospital; Grenoble France
| | - Matthieu Roustit
- Université Grenoble Alpes; Grenoble France
- INSERM; Grenoble France
- Clinical Pharmacology Unit; INSERM CIC1406; Grenoble University Hospital; Grenoble France
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71
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Wong BJ, Hollowed CG. Current concepts of active vasodilation in human skin. Temperature (Austin) 2016; 4:41-59. [PMID: 28349094 PMCID: PMC5356216 DOI: 10.1080/23328940.2016.1200203] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/07/2016] [Accepted: 06/07/2016] [Indexed: 10/30/2022] Open
Abstract
In humans, an increase in internal core temperature elicits large increases in skin blood flow and sweating. The increase in skin blood flow serves to transfer heat via convection from the body core to the skin surface while sweating results in evaporative cooling of the skin. Cutaneous vasodilation and sudomotor activity are controlled by a sympathetic cholinergic active vasodilator system that is hypothesized to operate through a co-transmission mechanism. To date, mechanisms of cutaneous active vasodilation remain equivocal despite many years of research by several productive laboratory groups. The purpose of this review is to highlight recent advancements in the field of cutaneous active vasodilation framed in the context of some of the historical findings that laid the groundwork for our current understanding of cutaneous active vasodilation.
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Affiliation(s)
- Brett J. Wong
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA, USA
| | - Casey G. Hollowed
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA, USA
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72
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Wenner MM, Taylor HS, Stachenfeld NS. Peripheral Microvascular Vasodilatory Response to Estradiol and Genistein in Women with Insulin Resistance. Microcirculation 2016; 22:391-9. [PMID: 25996650 DOI: 10.1111/micc.12208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/14/2015] [Indexed: 11/26/2022]
Abstract
OBJECTIVE E2 enhances vasodilation in healthy women, but vascular effects of the phytoestrogen GEN are still under investigation. IR compromises microvascular function. We therefore examined the interaction of E2 , GEN, and IR on microvascular vasodilatory responsiveness. METHODS We hypothesized that E2 and GEN increase microvascular vasodilation in healthy women (control, n = 8, 23 ± 2 year, BMI: 25.9 ± 2.9 kg/m2) but not in women with IR (n = 7, 20 ± 1 year, BMI: 27.3 ± 3.0 kg/m2). We used the cutaneous circulation as a model of microvascular vasodilatory function. We determined CVC with laser Doppler flowmetry and beat-to-beat blood pressure during local cutaneous heating (42 °C) with E2 or GEN microdialysis perfusions. Because heat-induced vasodilation is primarily an NO-mediated response, we examined microvascular vasodilation with and without L-NMMA. RESULTS In C, E2 enhanced CVC (94.4 ± 2.6% vs. saline 81.6 ± 4.2% CVCmax , p < 0.05), which was reversed with L-NMMA (80.9 ± 7.8% CVCmax , p < 0.05), but GEN did not affect vasodilation. Neither E2 nor GEN altered CVC in IR, although L-NMMA attenuated CVC during GEN. CONCLUSIONS Our study does not support improved microvascular responsiveness during GEN exposure in healthy young women, and demonstrates that neither E2 nor GEN improves microvascular vasodilatory responsiveness in women with IR.
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Affiliation(s)
- Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, USA
| | - Hugh S Taylor
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut, USA
| | - Nina S Stachenfeld
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut, USA.,The John B. Pierce Laboratory, New Haven, Connecticut.,Yale School of Public Health, New Haven, Connecticut, USA
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73
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Hodges GJ, McGarr GW, Mallette MM, Del Pozzi AT, Cheung SS. The contribution of sensory nerves to the onset threshold for cutaneous vasodilatation during gradual local skin heating of the forearm and leg. Microvasc Res 2016; 105:1-6. [DOI: 10.1016/j.mvr.2015.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 11/03/2015] [Accepted: 12/08/2015] [Indexed: 10/22/2022]
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74
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Fujii N, Singh MS, Halili L, Boulay P, Sigal RJ, Kenny GP. Cutaneous vascular and sweating responses to intradermal administration of prostaglandin E1 and E2 in young and older adults: a role for nitric oxide? Am J Physiol Regul Integr Comp Physiol 2016; 310:R1064-72. [PMID: 27101302 DOI: 10.1152/ajpregu.00538.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/06/2016] [Indexed: 01/28/2023]
Abstract
Cyclooxygenase (COX) contributes to cutaneous vasodilation and sweating responses; however, the mechanisms underpinning these responses remain unknown. We hypothesized that prostaglandin E1 (PGE1) and E2 (PGE2) (COX-derived vasodilator products) directly mediate cutaneous vasodilation and sweating through nitric oxide synthase (NOS)-dependent mechanisms in young adults. Furthermore, we hypothesized that this response is diminished in older adults, since aging attenuates COX-dependent cutaneous vasodilation and sweating. In 9 young (22 ± 5 yr) and 10 older (61 ± 6 yr) adults, cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites receiving incremental doses (0.05, 0.5, 5, 50, 500 μM each for 25 min) of PGE1 or PGE2 with and without coadministration of 10 mM N(ω)-nitro-l-arginine, a nonspecific NOS inhibitor. N(ω)-nitro-l-arginine attenuated PGE1-mediated increases in CVC at all concentrations in young adults, whereas it reduced PGE2-mediated increases in CVC at lower concentrations (0.05-0.5 μM) in older adults (all P < 0.05). However, the magnitude of the PGE1- and PGE2-mediated increases in CVC did not differ between groups (all P > 0.05). Neither PGE1 nor PGE2 increased sweat rate at any of the administered concentrations for either the young or older adults (all P > 0.05). We show that although cutaneous vascular responsiveness to PGE1 and PGE2 is similar between young and older adults, the cutaneous vasodilator response is partially mediated through NOS albeit via low-to-high concentrations of PGE1 in young adults and low concentrations of PGE2 in older adults, respectively. We also show that in both young and older adults, PGE1 and PGE2 do not increase sweat rate under normothermic conditions.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Maya Sarah Singh
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Lyra Halili
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada; and
| | - Ronald J Sigal
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
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75
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Fujii N, Meade RD, Minson CT, Brunt VE, Boulay P, Sigal RJ, Kenny GP. Cutaneous blood flow during intradermal NO administration in young and older adults: roles for calcium-activated potassium channels and cyclooxygenase? Am J Physiol Regul Integr Comp Physiol 2016; 310:R1081-7. [PMID: 27053645 DOI: 10.1152/ajpregu.00041.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/30/2016] [Indexed: 01/22/2023]
Abstract
Nitric oxide (NO) increases cutaneous blood flow; however, the underpinning mechanism(s) remains to be elucidated. We hypothesized that the cutaneous blood flow response during intradermal administration of sodium nitroprusside (SNP, a NO donor) is regulated by calcium-activated potassium (KCa) channels and cyclooxygenase (COX) in young adults. We also hypothesized that these contributions are diminished in older adults given that aging can downregulate KCa channels and reduce COX-derived vasodilator prostanoids. In 10 young (23 ± 5 yr) and 10 older (54 ± 4 yr) adults, cutaneous vascular conductance (CVC) was measured at four forearm skin sites infused with 1) Ringer (Control), 2) 50 mM tetraethylammonium (TEA), a nonspecific KCa channel blocker, 3) 10 mM ketorolac, a nonspecific COX inhibitor, or 4) 50 mM TEA + 10 mM ketorolac via intradermal microdialysis. All skin sites were coinfused with incremental doses of SNP (0.005, 0.05, 0.5, 5, and 50 mM each for 25 min). During SNP administration, CVC was similar at the ketorolac site (0.005-50 mM, all P > 0.05) relative to Control, but lower at the TEA and TEA + ketorolac sites (0.005-0.05 mM, all P < 0.05) in young adults. In older adults, ketorolac increased CVC relative to Control during 0.005-0.05 mM SNP administration (all P < 0.05), but this increase was not observed when TEA was coadministered (all P > 0.05). Furthermore, TEA alone did not modulate CVC during any concentration of SNP administration in older adults (all P > 0.05). We show that during low-dose NO administration (e.g., 0.005-0.05 mM), KCa channels contribute to cutaneous blood flow regulation in young adults; however, in older adults, COX inhibition increases cutaneous blood flow through a KCa channel-dependent mechanism.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | | | - Vienna E Brunt
- Department of Human Physiology, The University of Oregon, Eugene, Oregon
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada; and
| | - Ronald J Sigal
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
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76
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Halili L, Singh MS, Fujii N, Alexander LM, Kenny GP. Endothelin-1 modulates methacholine-induced cutaneous vasodilatation but not sweating in young human skin. J Physiol 2016; 594:3439-52. [PMID: 26846374 DOI: 10.1113/jp271735] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/29/2016] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS Endothelin-1 (ET-1) is a potent endothelial-derived vasoconstrictor that may modulate cholinergic cutaneous vascular regulation. Endothelin receptors are also expressed on the human eccrine sweat gland, although it remains unclear whether ET-1 modulates cholinergic sweating. We investigated whether ET-1 attenuates cholinergic cutaneous vasodilatation and sweating through a nitric oxide synthase (NOS)-dependent mechanism. Our findings show that ET-1 attenuates methacholine-induced cutaneous vasodilatation through a NOS-independent mechanism. We also demonstrate that ET-1 attenuates cutaneous vasodilatation in response to sodium nitroprusside, suggesting that ET-1 diminishes the dilatation capacity of vascular smooth muscle cells. We show that ET-1 does not modulate methacholine-induced sweating at any of the administered concentrations. Our findings advance our knowledge pertaining to the peripheral control underpinning the regulation of cutaneous blood flow and sweating and infer that ET-1 may attenuate the heat loss responses of cutaneous blood flow, but not sweating. ABSTRACT The present study investigated the effect of endothelin-1 (ET-1) on cholinergic mechanisms of end-organs (i.e. skin blood vessels and sweat glands) for heat dissipation. We evaluated the hypothesis that ET-1 attenuates cholinergic cutaneous vasodilatation and sweating through a nitric oxide synthase (NOS)-dependent mechanism. Cutaneous vascular conductance (CVC) and sweat rate were assessed in three protocols: in Protocol 1 (n = 8), microdialysis sites were perfused with lactated Ringer solution (Control), 40 pm, 4 nm or 400 nm ET-1; in Protocol 2 (n = 11) sites were perfused with lactated Ringer solution (Control), 400 nm ET-1, 10 mm N(G) -nitro-l-arginine (l-NNA; a NOS inhibitor) or a combination of 400 nm ET-1 and 10 mm l-NNA; in Protocol 3 (n = 8), only two sites (Control and 400 nm ET-1) were utilized to assess the influence of ET-1 on the dilatation capacity of vascular smooth muscle cells (sodium nitroprusside; SNP). Methacholine (MCh) was co-administered in a dose-dependent manner (0.0125, 0.25, 5, 100, 2000 mm, each for 25 min) at all skin sites. ET-1 at 400 nm (P < 0.05) compared to lower doses (40 pm and 4 nm) (all P > 0.05) significantly attenuated increases in CVC in response to 0.25 and 5 mm MCh. A high dose of ET-1 (400 nm) co-infused with l-NNA further attenuated CVC during 0.25, 5 and 100 mm MCh administration relative to the ET-1 site (all P < 0.05). Cutaneous vasodilatation in response to SNP was significantly blunted after administration of 400 nm ET-1 (P < 0.05). We show that ET-1 attenuates cutaneous vasodilatation through a NOS-independent mechanism, possibly through a vascular smooth muscle cell-dependent mechanism, and methacholine-induced sweating is not altered by ET-1.
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Affiliation(s)
- 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
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA, USA
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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77
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Fujii N, Meade RD, Alexander LM, Akbari P, Foudil-Bey I, Louie JC, Boulay P, Kenny GP. iNOS-dependent sweating and eNOS-dependent cutaneous vasodilation are evident in younger adults, but are diminished in older adults exercising in the heat. J Appl Physiol (1985) 2016; 120:318-27. [PMID: 26586908 PMCID: PMC4740499 DOI: 10.1152/japplphysiol.00714.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/16/2015] [Indexed: 12/12/2022] Open
Abstract
Nitric oxide synthase (NOS) contributes to sweating and cutaneous vasodilation during exercise in younger adults. We hypothesized that endothelial NOS (eNOS) and neuronal NOS (nNOS) mediate NOS-dependent sweating, whereas eNOS induces NOS-dependent cutaneous vasodilation in younger adults exercising in the heat. Further, aging may upregulate inducible NOS (iNOS), which may attenuate sweating and cutaneous vasodilator responses. We hypothesized that iNOS inhibition would augment sweating and cutaneous vasodilation in exercising older adults. Physically active younger (n = 12, 23 ± 4 yr) and older (n = 12, 60 ± 6 yr) adults performed two 30-min bouts of cycling at a fixed rate of metabolic heat production (400 W) in the heat (35°C). Sweat rate and cutaneous vascular conductance (CVC) were evaluated at four intradermal microdialysis sites with: 1) lactated Ringer (control), 2) nNOS inhibitor (nNOS-I, NPLA), 3) iNOS inhibitor (iNOS-I, 1400W), or 4) eNOS inhibitor (eNOS-I, LNAA). In younger adults during both exercise bouts, all inhibitors decreased sweating relative to control, albeit a lower sweat rate was observed at iNOS-I compared with eNOS-I and nNOS-I sites (all P < 0.05). CVC at the eNOS-I site was lower than control in younger adults throughout the intermittent exercise protocol (all P < 0.05). In older adults, there were no differences between control and iNOS-I sites for sweating and CVC during both exercise bouts (all P > 0.05). We show that iNOS and eNOS are the main contributors to NOS-dependent sweating and cutaneous vasodilation, respectively, in physically active younger adults exercising in the heat, and that iNOS inhibition does not alter sweating or cutaneous vasodilation in exercising physically active older adults.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania; and
| | - Pegah Akbari
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Imane Foudil-Bey
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Jeffrey C Louie
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
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78
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Del Pozzi AT, Miller JT, Hodges GJ. The effect of heating rate on the cutaneous vasomotion responses of forearm and leg skin in humans. Microvasc Res 2016; 105:77-84. [PMID: 26808211 DOI: 10.1016/j.mvr.2016.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 11/19/2022]
Abstract
We examined skin blood flow (SkBF) and vasomotion in the forearm and leg using laser-Doppler fluxmetry (LDF) and spectral analysis to investigate endothelial, sympathetic, and myogenic activities in response to slow (0.1 °C·10 s(-1)) and fast (0.5 °C·10 s(-1)) local heating. At 33 °C (thermoneutral) endothelial activity was higher in the legs than the forearms (P ≤ 0.02). Fast-heating increased SkBF more than slow heating (P=0.037 forearm; P=0.002 leg). At onset of 42 °C, endothelial (P=0.043 forearm; P=0.48 leg) activity increased in both regions during the fast-heating protocol. Following prolonged heating (42 °C) endothelial activity was higher in both the forearm (P=0.002) and leg (P<0.001) following fast-heating. These results confirm regional differences in the response to local heating and suggest that the greater increase in SkBF in response to fast local heating is initially due to increased endothelial and sympathetic activity. Furthermore, with sustained local skin heating, greater vasodilatation was observed with fast heating compared to slow heating. These data indicate that this difference is due to greater endothelial activity following fast heating compared to slow heating, suggesting that the rate of skin heating may alter the mechanisms contributing to cutaneous vasodilatation.
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Affiliation(s)
- Andrew T Del Pozzi
- Integrative Exercise Physiology Laboratory, School of Kinesiology, Ball State University, Muncie, IN 47306, United States
| | - James T Miller
- Exercise Physiology Laboratory, Department of Kinesiology, The University of Alabama, Tuscaloosa, AL 35487, United States
| | - Gary J Hodges
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.
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79
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Smith CJ, Johnson JM. Responses to hyperthermia. Optimizing heat dissipation by convection and evaporation: Neural control of skin blood flow and sweating in humans. Auton Neurosci 2016; 196:25-36. [PMID: 26830064 DOI: 10.1016/j.autneu.2016.01.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 01/05/2023]
Abstract
Under normothermic, resting conditions, humans dissipate heat from the body at a rate approximately equal to heat production. Small discrepancies between heat production and heat elimination would, over time, lead to significant changes in heat storage and body temperature. When heat production or environmental temperature is high the challenge of maintaining heat balance is much greater. This matching of heat elimination with heat production is a function of the skin circulation facilitating heat transport to the body surface and sweating, enabling evaporative heat loss. These processes are manifestations of the autonomic control of cutaneous vasomotor and sudomotor functions and form the basis of this review. We focus on these systems in the responses to hyperthermia. In particular, the cutaneous vascular responses to heat stress and the current understanding of the neurovascular mechanisms involved. The available research regarding cutaneous active vasodilation and vasoconstriction is highlighted, with emphasis on active vasodilation as a major responder to heat stress. Involvement of the vasoconstrictor and active vasodilator controls of the skin circulation in the context of heat stress and nonthermoregulatory reflexes (blood pressure, exercise) are also considered. Autonomic involvement in the cutaneous vascular responses to direct heating and cooling of the skin are also discussed. We examine the autonomic control of sweating, including cholinergic and noncholinergic mechanisms, the local control of sweating, thermoregulatory and nonthermoregulatory reflex control and the possible relationship between sudomotor and cutaneous vasodilator function. Finally, we comment on the clinical relevance of these control schemes in conditions of autonomic dysfunction.
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Affiliation(s)
- Caroline J Smith
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608-2071, United States
| | - John M Johnson
- Department of Physiology, University of Texas Health Science Center, San Antonio, TX 78229-3901, United States
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80
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Harvey JC, Roseguini BT, Goerger BM, Fallon EA, Wong BJ. Acute Thermotherapy Prevents Impairments in Cutaneous Microvascular Function Induced by a High Fat Meal. J Diabetes Res 2016; 2016:1902325. [PMID: 27595112 PMCID: PMC4993934 DOI: 10.1155/2016/1902325] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 06/09/2016] [Accepted: 07/05/2016] [Indexed: 12/20/2022] Open
Abstract
We tested the hypothesis that a high fat meal (HFM) would impair cutaneous vasodilation, while thermotherapy (TT) would reverse the detrimental effects. Eight participants were instrumented with skin heaters and laser-Doppler (LD) probes and tested in three trials: control, HFM, and HFM + TT. Participants wore a water-perfused suit perfused with 33°C (control and HFM) or 50°C (HFM + TT) water. Participants consumed 1 g fat/kg body weight. Blood samples were taken at baseline and two hours post-HFM. Blood pressure was measured every 5-10 minutes. Microvascular function was assessed via skin local heating from 33°C to 39°C two hours after HFM. Cutaneous vascular conductance (CVC) was calculated and normalized to maximal vasodilation (%CVCmax). HFM had no effect on initial peak (48 ± 4 %CVCmax) compared to control (49 ± 4 %CVCmax) but attenuated the plateau (51 ± 4 %CVCmax) compared to control (63 ± 4 %CVCmax, P < 0.001). Initial peak was augmented in HFM + TT (66 ± 4 %CVCmax) compared to control and HFM (P < 0.05), while plateau (73 ± 3 % CVCmax) was augmented only compared to the HFM trial (P < 0.001). These data suggest that HFM negatively affects cutaneous vasodilation but can be minimized by TT.
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Affiliation(s)
- Jennifer C. Harvey
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA 30302-3975, USA
| | - Bruno T. Roseguini
- Department of Health & Kinesiology, Purdue University, West Lafayette, IN 47907, USA
| | - Benjamin M. Goerger
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA 30302-3975, USA
| | - Elizabeth A. Fallon
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA 30302-3975, USA
| | - Brett J. Wong
- Department of Kinesiology & Health, Georgia State University, Atlanta, GA 30302-3975, USA
- *Brett J. Wong:
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81
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Brunt VE, Fujii N, Minson CT. Endothelial-derived hyperpolarization contributes to acetylcholine-mediated vasodilation in human skin in a dose-dependent manner. J Appl Physiol (1985) 2015; 119:1015-22. [PMID: 26384409 DOI: 10.1152/japplphysiol.00201.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 09/16/2015] [Indexed: 11/22/2022] Open
Abstract
Cutaneous acetylcholine (ACh)-mediated dilation is commonly used to assess microvascular function, but the mechanisms of dilation are poorly understood. Depending on dose and method of administration, nitric oxide (NO) and prostanoids are involved to varying extents and the roles of endothelial-derived hyperpolarizing factors (EDHFs) are unclear. In the present study, five incremental doses of ACh (0.01-100 mM) were delivered either as a 1-min bolus (protocol 1, n = 12) or as a ≥20-min continuous infusion (protocol 2, n = 10) via microdialysis fibers infused with 1) lactated Ringer, 2) tetraethylammonium (TEA) [a calcium-activated potassium channel (KCa) and EDHF inhibitor], 3) L-NNA+ketorolac [NO synthase (NOS) and cyclooxygenase (COX) inhibitors], and 4) TEA+L-NNA+Ketorolac. The hyperemic response was characterized as peak and area under the curve (AUC) cutaneous vascular conductance (CVC) for bolus infusions or plateau CVC for continuous infusions, and reported as %maximal CVC. In protocol 1, TEA, alone and combined with NOS+COX inhibition, attenuated peak CVC (100 mM Ringer 59 ± 6% vs. TEA 43 ± 5%, P < 0.05; L-NNA+ketorolac 35 ± 4% vs. TEA+L-NNA+ketorolac 25 ± 4%, P < 0.05) and AUC (Ringer 25,414 ± 3,528 vs. TEA 21,403 ± 3,416%·s, P < 0.05; L-NNA+ketorolac 25,628 ± 3,828%(.)s vs. TEA+L-NNA+ketorolac 20,772 ± 3,711%·s, P < 0.05), although these effects were only significant at the highest dose of ACh. At lower doses, TEA lengthened the total time of the hyperemic response (10 mM Ringer 609 ± 78 s vs. TEA 860 ± 67 s, P < 0.05). In protocol 2, TEA alone did not affect plateau CVC, but attenuated plateau in combination with NOS+COX inhibition (100 mM 50.4 ± 6.6% vs. 30.9 ± 6.3%, P < 0.05). Therefore, EDHFs contribute to cutaneous ACh-mediated dilation, but their relative contribution is altered by the dose and infusion procedure.
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Affiliation(s)
- Vienna E Brunt
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | - Naoto Fujii
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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82
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Bocchi L, Evangelisti A, Barrella M, Bevilacqua M. Shape analysis of the microcirculatory flow wave. Physiol Meas 2015; 36:2147-58. [PMID: 26333986 DOI: 10.1088/0967-3334/36/10/2147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The cardiovascular system and its alterations are a crucial aspect of physiology and medicine. Non-invasive assessment of the functional properties of circulation is of considerable interest to clinicians and physiologists. In this work we investigate the possibility of detecting alterations of the flow waveform in microcirculation, using non-invasive measurements based on a laser Doppler flowmeter. As a test case, we focus on the effect of ageing. Skin is warmed up to a fixed temperature (44 °C) during measurement, to increase blood flow. The shape of the perfusion waveform during each heart beat after the flow was stabilized was used to estimate dynamic parameters of the microcirculatory system. Both the wave rise time, defined as the delay between the diastolic minimum and the following systolic maximum, and the oscillation fraction, defined as the normalized difference between the maximum and minimum flow, present significant variation with age.
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Affiliation(s)
- L Bocchi
- Department of Information Engineering, University of Florence, 50121 Florence, Italy
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83
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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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84
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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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85
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Kutz JL, Greaney JL, Santhanam L, Alexander LM. Evidence for a functional vasodilatatory role for hydrogen sulphide in the human cutaneous microvasculature. J Physiol 2015; 593:2121-9. [PMID: 25639684 DOI: 10.1113/jp270054] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 01/23/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Hydrogen sulphide (H2 S) is vasoprotective, attenuates inflammation and modulates blood pressure in animal models; however, its specific mechanistic role in the human vasculature remains unclear. In the present study, we report the novel finding that the enzymes responsible for endogenous H2 S production, cystathionine-γ-lyase and 3-mercaptopyruvate sulphurtransferase, are expressed in the human cutaneous circulation. Functionally, we show that H2 S-induced cutaneous vasodilatation is mediated, in part, by tetraethylammonium-sensitive calcium-dependent potassium channels and not by ATP-sensitive potassium channels. In addition, nitric oxide and cyclo-oxygenase-derived byproducts are required for full expression of exogenous H2 S-mediated cutaneous vasodilatation. Future investigations of the potential role for H2 S with respect to modulating vascular function in humans may have important clinical implications for understanding the mechanisms underlying vascular dysfunction characteristic of multiple cardiovascular pathologies. ABSTRACT The present study aimed to identify the presence of cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulphurtransferase (3-MST), which endogenously produce hydrogen sulphide (H2 S), and to functionally examine the mechanisms of H2 S-induced vasodilatation in the human cutaneous microcirculation. CSE and 3-MST were quantified in forearm skin samples from 5 healthy adults (24 ± 3 years) using western blot analysis. For functional studies, microdialysis fibres were placed in the forearm skin of 12 healthy adults (25 ± 3 years) for graded infusions (0.01-100 mm) of sodium sulphide (Na2 S) and sodium hydrogen sulphide (NaHS). To define the mechanisms mediating H2 S-induced vasodilatation, microdialysis fibres were perfused with Ringer solution (control), a ATP-sensitive potassium channel (KATP ) inhibitor, an intermediate calcium-dependent potassium channel (KCa ) inhibitor, a non-specific KCa channel inhibitor or triple blockade. To determine the interaction of H2 S-mediated vasodilatation with nitric oxide (NO) and cyclo-oxygenase (COX) signalling pathways, microdialysis fibres were perfused with Ringer solution (control), a non-specific NO synthase inhibitor, a non-selective COX inhibitor or combined inhibition during perfusion of increasing doses of Na2 S. CSE and 3-MST were expressed in all skin samples. Na2 S and NaHS elicited dose-dependent vasodilatation. Non-specific KCa channel inhibition and triple blockade blunted Na2 S-induced vasodilatation (P < 0.05), whereas KATP and intermediate KCa channel inhibition had no effect (P > 0.05). Separate and combined inhibition of NO and COX attenuated H2 S-induced vasodilatation (all P < 0.05). CSE and 3-MST are expressed in the human microvasculature. Exogenous H2 S elicits cutaneous vasodilatation mediated by KCa channels and has a functional interaction with both NO and COX vasodilatatory signalling pathways.
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Affiliation(s)
- Jessica L Kutz
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA, USA
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86
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Del Pozzi AT, Hodges GJ. Comparison of the noradrenergic sympathetic nerve contribution during local skin heating at forearm and leg sites in humans. Eur J Appl Physiol 2015; 115:1155-64. [DOI: 10.1007/s00421-014-3097-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 12/24/2014] [Indexed: 01/08/2023]
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87
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Humeau-Heurtier A, Mahé G, Abraham P. Microvascular blood flow monitoring with laser speckle contrast imaging using the generalized differences algorithm. Microvasc Res 2015; 98:54-61. [PMID: 25576743 DOI: 10.1016/j.mvr.2014.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/22/2014] [Accepted: 12/27/2014] [Indexed: 10/24/2022]
Abstract
Laser speckle contrast imaging (LSCI) is a full-field optical technique to monitor microvascular blood flow with high spatial and temporal resolutions. It is used in many medical fields such as dermatology, vascular medicine, or neurosciences. However, LSCI leads to a large amount of data: image sampling frequency is often of several Hz and recordings usually last several minutes. Therefore, clinicians often perform regions of interest in which a spatial averaging of blood flow is performed and the result is followed with time. Unfortunately, this leads to a poor spatial resolution for the analyzed data. At the same time, a higher spatial resolution for the perfusion maps is wanted. To get over this dilemma we propose a new post-acquisition visual representation for LSCI perfusion data using the so-called generalized differences (GD) algorithm. From a stack of perfusion images, the procedure leads to a new single image with the same spatial resolution as the original images and this new image reflects perfusion changes. The algorithm is herein applied on simulated stacks of images and on experimental LSCI perfusion data acquired in three different situations with a commercialized laser speckle contrast imager. The results show that the GD algorithm provides a new way of visualizing LSCI perfusion data.
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Affiliation(s)
- Anne Humeau-Heurtier
- University of Angers, LARIS - Laboratoire Angevin de Recherche en Ingénierie des Systèmes, 62 Avenue Notre-Dame du Lac, 49000 Angers, France.
| | - Guillaume Mahé
- University of Rennes 1, CHU of Rennes, Pôle Imagerie Médicale et Explorations Fonctionnelles, 35033 Rennes Cedex 9, France; INSERM, CIC 1414 "Ischemia, Macro and Microcirculation" Group, 35033 Rennes Cedex 9, France
| | - Pierre Abraham
- University of Angers, CHU of Angers, Laboratoire de Physiologie et d'Explorations Vasculaires, UMR CNRS 6214-INSERM 1083, 49033 Angers Cedex 01, France
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88
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Johnson JM, Minson CT, Kellogg DL. Cutaneous vasodilator and vasoconstrictor mechanisms in temperature regulation. Compr Physiol 2014; 4:33-89. [PMID: 24692134 DOI: 10.1002/cphy.c130015] [Citation(s) in RCA: 241] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this review, we focus on significant developments in our understanding of the mechanisms that control the cutaneous vasculature in humans, with emphasis on the literature of the last half-century. To provide a background for subsequent sections, we review methods of measurement and techniques of importance in elucidating control mechanisms for studying skin blood flow. In addition, the anatomy of the skin relevant to its thermoregulatory function is outlined. The mechanisms by which sympathetic nerves mediate cutaneous active vasodilation during whole body heating and cutaneous vasoconstriction during whole body cooling are reviewed, including discussions of mechanisms involving cotransmission, NO, and other effectors. Current concepts for the mechanisms that effect local cutaneous vascular responses to local skin warming and cooling are examined, including the roles of temperature sensitive afferent neurons as well as NO and other mediators. Factors that can modulate control mechanisms of the cutaneous vasculature, such as gender, aging, and clinical conditions, are discussed, as are nonthermoregulatory reflex modifiers of thermoregulatory cutaneous vascular responses.
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Affiliation(s)
- John M Johnson
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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89
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Fujii N, McGinn R, Paull G, Stapleton JM, Meade RD, Kenny GP. Cyclooxygenase inhibition does not alter methacholine-induced sweating. J Appl Physiol (1985) 2014; 117:1055-62. [PMID: 25213633 PMCID: PMC4217047 DOI: 10.1152/japplphysiol.00644.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/04/2014] [Indexed: 01/22/2023] Open
Abstract
Cholinergic agents (e.g., methacholine) induce cutaneous vasodilation and sweating. Reports indicate that either nitric oxide (NO), cyclooxygenase (COX), or both can contribute to cholinergic cutaneous vasodilation. Also, NO is reportedly involved in cholinergic sweating; however, whether COX contributes to cholinergic sweating is unclear. Forearm sweat rate (ventilated capsule) and cutaneous vascular conductance (CVC, laser-Doppler perfusion units/mean arterial pressure) were evaluated in 10 healthy young (24 ± 4 yr) adults (7 men, 3 women) at four skin sites that were continuously perfused via intradermal microdialysis with 1) lactated Ringer (control), 2) 10 mM ketorolac (a nonselective COX inhibitor), 3) 10 mM N(G)-nitro-l-arginine methyl ester (l-NAME, a nonselective NO synthase inhibitor), or 4) a combination of 10 mM ketorolac + 10 mM l-NAME. At the four skin sites, methacholine was simultaneously infused in a dose-dependent manner (1, 10, 100, 1,000, 2,000 mM). Relative to the control site, forearm CVC was not influenced by ketorolac throughout the protocol (all P > 0.05), whereas l-NAME and ketorolac + l-NAME reduced forearm CVC at and above 10 mM methacholine (all P < 0.05). Conversely, there was no main effect of treatment site (P = 0.488) and no interaction of methacholine dose and treatment site (P = 0.711) on forearm sweating. Thus forearm sweating (in mg·min(-1)·cm(-2)) from baseline up to the maximal dose of methacholine was not different between the four sites (at 2,000 mM, control 0.50 ± 0.23, ketorolac 0.44 ± 0.23, l-NAME 0.51 ± 0.22, and ketorolac + l-NAME 0.51 ± 0.23). We show that both NO synthase and COX inhibition do not influence cholinergic sweating induced by 1-2,000 mM methacholine.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Gabrielle Paull
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Jill M Stapleton
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
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90
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Stapleton JM, Fujii N, McGinn R, McDonald K, Kenny GP. Age-related differences in postsynaptic increases in sweating and skin blood flow postexercise. Physiol Rep 2014; 2:e12078. [PMID: 25347861 PMCID: PMC4187563 DOI: 10.14814/phy2.12078] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/03/2014] [Accepted: 06/10/2014] [Indexed: 11/24/2022] Open
Abstract
The influence of peripheral factors on the control of heat loss responses (i.e., sweating and skin blood flow) in the postexercise period remains unknown in young and older adults. Therefore, in eight young (22 ± 3 years) and eight older (65 ± 3 years) males, we examined dose-dependent responses to the administration of acetylcholine (ACh) and methacholine (MCh) for sweating (ventilated capsule), as well as to ACh and sodium nitroprusside (SNP) for cutaneous vascular conductance (CVC, laser-Doppler flowmetry, % of max). In order to assess if peripheral factors are involved in the modulation of thermoeffector activity postexercise, pharmacological agonists were perfused via intradermal microdialysis on two separate days: (1) at rest ( DOSE: ) and (2) following a 30-min bout of exercise ( EX+: DOSE: ). No differences in sweat rate between the DOSE and Ex+DOSE conditions at either ACh or MCh were observed for the young (ACh: P = 0.992 and MCh: P = 0.710) or older (ACh: P = 0.775 and MCh: P = 0.738) adults. Similarly, CVC was not different between the DOSE and Ex+DOSE conditions for the young (ACh: P = 0.123 and SNP: P = 0.893) or older (ACh: P = 0.113 and SNP: P = 0.068) adults. Older adults had a lower sweating response for both the DOSE (ACh: P = 0.049 and MCh: P = 0.006) and Ex+DOSE (ACh: P = 0.050 and MCh: P = 0.029) conditions compared to their younger counterparts. These findings suggest that peripheral factors do not modulate postexercise sweating and skin blood flow in both young and older adults. Additionally, sweat gland function is impaired in older adults, albeit the impairments were not exacerbated during postexercise recovery.
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Affiliation(s)
- Jill M. Stapleton
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Katherine McDonald
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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91
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DuPont JJ, Ramick MG, Farquhar WB, Townsend RR, Edwards DG. NADPH oxidase-derived reactive oxygen species contribute to impaired cutaneous microvascular function in chronic kidney disease. Am J Physiol Renal Physiol 2014; 306:F1499-506. [PMID: 24761000 PMCID: PMC4059972 DOI: 10.1152/ajprenal.00058.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/21/2014] [Indexed: 01/11/2023] Open
Abstract
Oxidative stress promotes vascular dysfunction in chronic kidney disease (CKD). We utilized the cutaneous circulation to test the hypothesis that reactive oxygen species derived from NADPH oxidase and xanthine oxidase impair nitric oxide (NO)-dependent cutaneous vasodilation in CKD. Twenty subjects, 10 stage 3 and 4 patients with CKD (61 ± 4 yr; 5 men/5 women; eGFR: 39 ± 4 ml·min(-1)·1.73 m(-2)) and 10 healthy controls (55 ± 2 yr; 4 men/6 women; eGFR: >60 ml·min(-1)·1.73 m(-2)) were instrumented with 4 intradermal microdialysis fibers for the delivery of 1) Ringer solution (Control), 2) 10 μM tempol (scavenge superoxide), 3) 100 μM apocynin (NAD(P)H oxidase inhibition), and 4) 10 μM allopurinol (xanthine oxidase inhibition). Skin blood flow was measured via laser-Doppler flowmetry during standardized local heating (42°C). N(g)-nitro-l-arginine methyl ester (L-NAME; 10 mM) was infused to quantify the NO-dependent portion of the response. Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum CVC achieved during sodium nitroprusside infusion at 43°C. Cutaneous vasodilation was attenuated in patients with CKD (77 ± 3 vs. 88 ± 3%, P = 0.01), but augmented with tempol and apocynin (tempol: 88 ± 2 (P = 0.03), apocynin: 91 ± 2% (P = 0.001). The NO-dependent portion of the response was reduced in patients with CKD (41 ± 4 vs. 58 ± 2%, P = 0.04), but improved with tempol and apocynin (tempol: 58 ± 3 (P = 0.03), apocynin: 58 ± 4% (P = 0.03). Inhibition of xanthine oxidase did not alter cutaneous vasodilation in either group (P > 0.05). These data suggest that NAD(P)H oxidase is a source of reactive oxygen species and contributes to microvascular dysfunction in patients with CKD.
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Affiliation(s)
- Jennifer J DuPont
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Meghan G Ramick
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; Department of Biological Sciences, University of Delaware, Newark, Delaware; and
| | - Raymond R Townsend
- Clinical and Translational Research Center, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David G Edwards
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; Department of Biological Sciences, University of Delaware, Newark, Delaware; and
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92
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Choi PJ, Brunt VE, Fujii N, Minson CT. New approach to measure cutaneous microvascular function: an improved test of NO-mediated vasodilation by thermal hyperemia. J Appl Physiol (1985) 2014; 117:277-83. [PMID: 24903917 DOI: 10.1152/japplphysiol.01397.2013] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cutaneous hyperemia in response to rapid skin local heating to 42°C has been used extensively to assess microvascular function. However, the response is dependent on both nitric oxide (NO) and endothelial-derived hyperpolarizing factors (EDHFs), and increases cutaneous vascular conductance (CVC) to ∼90-95% maximum in healthy subjects, preventing the study of potential means to improve cutaneous function. We sought to identify an improved protocol for isolating NO-dependent dilation. We compared nine heating protocols (combinations of three target temperatures: 36°C, 39°C, and 42°C, and three rates of heating: 0.1°C/s, 0.1°C/10 s, 0.1°C/min) in order to select two protocols to study in more depth (protocol 1; N = 6). Then, CVC was measured at four microdialysis sites receiving: 1) lactated Ringer solution (Control), 2) 50-mM tetraethylammonium (TEA) to inhibit EDHFs, 3) 20-mM nitro-L-arginine methyl ester (L-NAME) to inhibit NO synthase, and 4) TEA+L-NAME, in response to local heating either to 39°C at 0.1°C/s (protocol 2; N = 10) or 42°C at 0.1°C/min (protocol 3; N = 8). Rapid heating to 39°C increased CVC to 43.1 ± 5.2%CVCmax (Control), which was attenuated by L-NAME (11.4 ± 2.8%CVCmax; P < 0.001) such that 82.8 ± 4.2% of the plateau was attributable to NO. During gradual heating, 81.5 ± 3.3% of vasodilation was attributable to NO at 40°C, but at 42°C only 32.7 ± 7.8% of vasodilation was attributable to NO. TEA+L-NAME attenuated CVC beyond L-NAME at temperatures >40°C (43.4 ± 4.5%CVCmax at 42°C, P < 0.001 vs. L-NAME), suggesting a role of EDHFs at higher temperatures. Our findings suggest local heating to 39°C offers an improved approach for isolating NO-dependent dilation and/or assessing perturbations that may improve microvascular function.
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Affiliation(s)
- Patricia J Choi
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Vienna E Brunt
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Naoto Fujii
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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93
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Fujii N, Brunt VE, Minson CT. Tempol improves cutaneous thermal hyperemia through increasing nitric oxide bioavailability in young smokers. Am J Physiol Heart Circ Physiol 2014; 306:H1507-11. [PMID: 24682395 DOI: 10.1152/ajpheart.00886.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We recently found that young cigarette smokers display cutaneous vascular dysfunction relative to nonsmokers, which is partially due to reduced nitric oxide (NO) synthase (NOS)-dependent vasodilation. In this study, we tested the hypothesis that reducing oxidative stress improves NO bioavailability, enhancing cutaneous vascular function in young smokers. Ten healthy young male smokers, who had smoked for 6.3 ± 0.7 yr with an average daily consumption of 9.1 ± 0.7 cigarettes, were tested. Cutaneous vascular conductance (CVC) during local heating to 42°C at a rate of 0.1°C/s was evaluated as laser-Doppler flux divided by mean arterial blood pressure and normalized to maximal CVC, induced by local heating to 44°C plus sodium nitroprusside administration. We evaluated plateau CVC during local heating, which is known to be highly dependent on NO, at four intradermal microdialysis sites with 1) Ringer solution (control); 2) 10 μM 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol), a superoxide dismutase mimetic; 3) 10 mM N(ω)-nitro-l-arginine (l-NNA), a nonspecific NOS inhibitor; and 4) a combination of 10 μM tempol and 10 mM l-NNA. Tempol increased plateau CVC compared with the Ringer solution site (90.0 ± 2.3 vs. 77.6 ± 3.9%maximum, P = 0.028). Plateau CVC at the combination site (56.8 ± 4.5%maximum) was lower than the Ringer solution site (P < 0.001) and was not different from the l-NNA site (55.1 ± 4.6%maximum, P = 0.978), indicating the tempol effect was exclusively NO dependent. These data suggest that in young smokers, reducing oxidative stress improves cutaneous thermal hyperemia to local heating by enhancing NO production.
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Affiliation(s)
- Naoto Fujii
- Department of Human Physiology, The University of Oregon, Eugene, Oregon
| | - Vienna E Brunt
- Department of Human Physiology, The University of Oregon, Eugene, Oregon
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94
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Bruning RS, Kenney WL, Alexander LM. Altered skin flowmotion in hypertensive humans. Microvasc Res 2014; 97:81-7. [PMID: 24418051 DOI: 10.1016/j.mvr.2014.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 12/11/2013] [Accepted: 01/01/2014] [Indexed: 01/10/2023]
Abstract
Essential hypertensive humans exhibit attenuated cutaneous nitric oxide (NO)-dependent vasodilation. Using spectral analysis (fast Fourier transformation) we aimed to characterize the skin flowmotion contained in the laser-Doppler flowmetry recordings during local heating-induced vasodilation before and after concurrent pharmacological inhibition of nitric oxide synthase (NOS) in hypertensive and age-matched normotensive men and women. We hypothesized that hypertensive subjects would have lower total power spectral densities (PSDs), specifically in the frequency intervals associated with intrinsic endothelial and neurogenic control of the microvasculature. Furthermore, we hypothesized that NOS inhibition would attenuate the endothelial frequency interval. Laser-Doppler flowmetry recordings during local heating experiments from 18 hypertensive (MAP: 108±2mmHg) and 18 normotensive (MAP: 88±2mmHg) men and women were analyzed. Within site NO-dependent vasodilation was assessed by perfusion of a non-specific NOS inhibitor (N(G)-nitro-l-arginine methyl ester; l-NAME) through intradermal microdialysis during the heating-induced plateau in skin blood flow. Local heating-induced vasodilation increased total PSD for all frequency intervals (all p<0.001). Hypertensives had a lower total PSD (p=0.03) and absolute neurogenic frequency intervals (p<0.01) compared to the normotensives. When normalized as a percentage of total PSD, hypertensives had reduced neurogenic (p<0.001) and augmented myogenic contributions (p=0.04) to the total spectrum. NOS inhibition decreased total PSD (p<0.001) for both groups, but hypertensives exhibited lower absolute endothelial (p<0.01), neurogenic (p<0.05), and total PSD (p<0.001) frequency intervals compared to normotensives. These data suggest that essential hypertension results in altered neurogenic and NOS-dependent control of skin flowmotion and support the use of spectral analysis as a non-invasive technique to study vasoreactivity.
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Affiliation(s)
- R S Bruning
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA
| | - W L Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA
| | - L M Alexander
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA.
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95
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Puissant C, Abraham P, Durand S, Humeau-Heurtier A, Faure S, Rousseau P, Mahé G. [Endothelial function: role, assessment and limits]. ACTA ACUST UNITED AC 2013; 39:47-56. [PMID: 24355615 DOI: 10.1016/j.jmv.2013.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 10/24/2013] [Indexed: 12/16/2022]
Abstract
For several years, detecting and preventing cardiovascular diseases have become a major issue. Different methods have been developed to evaluate endothelial function. Endothelial dysfunction is one of the first steps leading to atherosclerosis. This review presents an insight into endothelial function, the interests of its assessment and methods for studying endothelial function. To date, the vascular endothelium must be considered as a specific organ with its own functions that contribute to the homeostasis of the cardiovascular system. Endothelial dysfunction typically corresponds to a decrease of nitric oxide NO bioavailability. Biological or physico-chemical methods may be used to assess dysfunction. Biological methods allow measuring NO metabolites and pro-inflammatory and vasoconstrictor mediators released by the endothelium. The physico-chemical methods include intra-coronary injections, plethysmography, flow-mediated dilation (FMD), digital plethysmography and optical techniques using laser (laser Doppler single-point, laser Doppler imager, laser speckle contrast imaging) that can be coupled with provocation tests (iontophoresis, microdialysis, post-ischemic hyperemia, local heating). The principle of each technique and its use in clinical practice are discussed. Studying endothelial dysfunction is a particularly promising field because of new drugs being developed. Nevertheless, assessment methodology still needs further development to enable reliable, non-invasive, reproducible, and inexpensive ways to analyze endothelial dysfunction.
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Affiliation(s)
- C Puissant
- Service des explorations fonctionnelles vasculaires, centre hospitalier universitaire, 49933 Angers cedex 9, France
| | - P Abraham
- Service des explorations fonctionnelles vasculaires, centre hospitalier universitaire, 49933 Angers cedex 9, France; Biologie neurovasculaire et mitochondriale intégrée (BNMI) - unité mixte UMR CNRS 6214/Inserm U 1083, faculté de médecine, LUNAM université, 49045 Angers, France
| | - S Durand
- EA 4334 motricity, interactions, and performance, LUNAM université, université du Maine, 72085 Le Mans cedex 9, France
| | - A Humeau-Heurtier
- Laboratoire d'ingénierie des systèmes automatisés (LISA), LUNAM université, université d'Angers, 49000 Angers, France
| | - S Faure
- Stress oxydant et pathologies métaboliques (SOPAM), Inserm U1063, LUNAM université, université d'Angers, 40045 Angers, France
| | - P Rousseau
- Département de chirurgie plastique, centre hospitalier universitaire, 49933 Angers cedex 9, France
| | - G Mahé
- Biologie neurovasculaire et mitochondriale intégrée (BNMI) - unité mixte UMR CNRS 6214/Inserm U 1083, faculté de médecine, LUNAM université, 49045 Angers, France; Pôle imagerie médicale, centre hospitalier universitaire Pontchaillou, 2, avenue du Pr-Léon-Bernard, 35033 Rennes cedex 9, France.
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96
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Hodges GJ, Sparks PA. Contributions of endothelial nitric oxide synthase, noradrenaline, and neuropeptide Y to local warming-induced cutaneous vasodilatation in men. Microvasc Res 2013; 90:128-34. [PMID: 24012636 DOI: 10.1016/j.mvr.2013.08.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/24/2013] [Accepted: 08/28/2013] [Indexed: 12/31/2022]
Abstract
We performed a two-part study to determine the roles of endothelial nitric oxide synthase (eNOS) and the vasoconstrictor nerves neurotransmitters noradrenaline (NA) and neuropeptide Y (NPY) in the cutaneous vasodilator response to local skin warming. Forearm skin sites were instrumented with intradermal microdialysis fibres, local heaters, and laser-Doppler flow (LDF) probes. Sites were locally heated from 34 to 42°C. LDF was expressed as cutaneous vascular conductance (CVC; LDF/mean arterial pressure). In Part I, we tested whether sympathetic noradrenergic nerves acted via eNOS. In 8 male participants, treatments were as follows: 1) untreated; 2) bretylium tosylate (BT), preventing sympathetic neurotransmitter release; 3) l-NAA to inhibit eNOS; and 4) combined BT+l-NAA. At treated sites, the initial peak response was markedly reduced, and the plateau phase response to 35min of local warming was also reduced (P<0.05), which was not different among those sites (P>0.05). In Part II, we tested whether NA and NPY were involved in the vasodilator response to local warming. In Part IIa, treatments were: 1) untreated; 2) propranolol and yohimbine to antagonize α- and β-receptors; 3) l-NAA; and 4) combined propranolol, yohimbine, and l-NAA. In Part IIb, conditions were: 1) untreated; 2) BIBP to antagonize Y1-receptors; 3) l-NAA; and 4) combined BIBP and l-NAA. All treatments caused a reduction in the initial peak and plateau responses to local skin warming (P<0.05). The results of Part II indicate that both NA and NPY play roles in the cutaneous vasodilator response and their actions are achieved via eNOS. These data indicate that NA and NPY are involved in the initial, rapid rise in skin blood flow at the onset of local skin warming. However, their vasodilator actions in response to local skin warming appears to be manifested through eNOS.
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Affiliation(s)
- Gary J Hodges
- Exercise Physiology Laboratory, Department of Kinesiology, The University of Alabama, Tuscaloosa, AL 35487, USA.
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97
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Brunt VE, Fujii N, Minson CT. No independent, but an interactive, role of calcium-activated potassium channels in human cutaneous active vasodilation. J Appl Physiol (1985) 2013; 115:1290-6. [PMID: 23970531 DOI: 10.1152/japplphysiol.00358.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In human cutaneous microvasculature, endothelium-derived hyperpolarizing factors (EDHFs) account for a large portion of vasodilation associated with local stimuli. Thus we sought to determine the role of EDHFs in active vasodilation (AVD) to passive heating in two protocols. Whole body heating was achieved using water-perfused suits (core temperature increase of 0.8-1.0°C), and skin blood flow was measured using laser-Doppler flowmetry. In the first protocol, four sites were perfused continuously via microdialysis with: 1) control; 2) tetraethylammonium (TEA) to block calcium-activated potassium (KCa) channels, and thus the actions of EDHFs; 3) N-nitro-l-arginine methyl ester (l-NAME) to inhibit nitric oxide synthase (NOS); and 4) TEA + l-NAME (n = 8). Data are presented as percent maximal cutaneous vascular conductance (CVC). TEA had no effect on AVD (CVC during heated plateau: control 57.4 ± 4.9% vs. TEA 63.2 ± 5.2%, P = 0.27), indicating EDHFs are not obligatory. l-NAME attenuated plateau CVC to 33.7 ± 5.4% (P < 0.01 vs. control); while TEA + l-NAME augmented plateau CVC compared with l-NAME alone (49.7 ± 5.3%, P = 0.02). From these data, it appears combined blockade of EDHFs and NOS necessitates dilation through other means, possibly through inward rectifier (KIR) and/or ATP-sensitive (KATP) potassium channels. To test this second hypothesis, we measured AVD at the following sites (n = 8): 1) control, 2) l-NAME, 3) l-NAME + TEA, and 4) l-NAME + TEA + barium chloride (BaCl2; KIR and KATP blocker). The addition of BaCl2 to l-NAME + TEA reduced plateau CVC to 32.7 ± 6.6% (P = 0.02 vs. l-NAME + TEA), which did not differ from the l-NAME site. These data combined demonstrate a complex interplay between vasodilatory pathways, with cross-talk between NO, KCa channels, and KIR and/or KATP channels.
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Affiliation(s)
- Vienna E Brunt
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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98
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Impaired skin microcirculation in paediatric patients with type 1 diabetes mellitus. Cardiovasc Diabetol 2013; 12:115. [PMID: 23937662 PMCID: PMC3751195 DOI: 10.1186/1475-2840-12-115] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/12/2013] [Indexed: 11/11/2022] Open
Abstract
Aims/hypothesis We used Laser Doppler Fluximetry (LDF) to define "normal" endothelial function in a large cohort of healthy children and adolescents and to evaluate skin microcirculation in paediatric patients with type 1 diabetes mellitus. Methods LDF was performed in 102 healthy children (12.8 ± 3.3 years of age; 48 male) and 68 patients (12.9 ± 3.3 years of age; 33 male). Duration of disease was 5.0 ± 3.97 years. Each participant sequentially underwent three stimulation protocols (localized thermal hyperaemia with localized warming to maximum 40°C, iontophoretic delivery of pilocarpine hydrochloride (PCH) and sodium nitroprusside (SNP)). The maximum relative increase in skin blood flow and the total relative response, i.e. the area under the curve (AUC) to each stimulus (AUCheat, AUCPCH, AUCSNP) was determined. In addition, the area of a right-angled triangle summarizing the time to and the amplitude of the first peak, which represents the axon reflex mediated neurogenic vasodilation (ARR) was calculated. Results In healthy controls, AUCheat, AUCPCH, AUCSNP, and ARR turned out to be independent of sex, age, and anthropometric values. Per parameter the 10th percentile generated from data of healthy controls was used as the lower threshold to define normal endothelial function. Diabetic patients showed significantly reduced vasodilatative response to either physical or pharmacological stimulation with SNP, whereas the response to PCH was comparable in both cohorts. In patients compared to controls i) a significantly higher frequency of impaired vasodilatation in response to heat and SNP was noted and ii) vascular response was classified as pathological in more than one of the parameters with significantly higher frequency. Conclusions/interpretation Skin microvascular endothelial dysfunction is already present in about 25% of paediatric type 1 diabetic patients suffering from type 1 diabetes for at least one year. Future studies are needed to assess the predictive value of endothelial dysfunction in the development of long-term (cardio)vascular comorbidity in these patients.
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99
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Roustit M, Cracowski JL. Assessment of endothelial and neurovascular function in human skin microcirculation. Trends Pharmacol Sci 2013; 34:373-84. [DOI: 10.1016/j.tips.2013.05.007] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 05/03/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
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100
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Puissant C, Abraham P, Durand S, Humeau-Heurtier A, Faure S, Lefthériotis G, Rousseau P, Mahé G. Reproducibility of non-invasive assessment of skin endothelial function using laser Doppler flowmetry and laser speckle contrast imaging. PLoS One 2013; 8:e61320. [PMID: 23620742 PMCID: PMC3631172 DOI: 10.1371/journal.pone.0061320] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 03/07/2013] [Indexed: 11/26/2022] Open
Abstract
Background Endothelial dysfunction precedes atherosclerosis. Vasodilation induced by acetylcholine (ACh) is a specific test of endothelial function. Reproducibility of laser techniques such as laser-Doppler-flowmetry (LDF) and Laser-speckle-contrast-imaging (LSCI) to detect ACh vasodilation is debated and results expressions lack standardization. We aimed to study at a 7-day interval (i) the inter-subject reproducibility, (ii) the intra-subjects reproducibility, and (iii) the effect of the results expressions over variability. Methods and Results Using LDF and LSCI simultaneously, we performed two different ACh-iontophoresis protocols. The maximal ACh vasodilation (peak-ACh) was expressed as absolute or normalized flow or conductance values. Inter-subject reproducibility was expressed as coefficient of variation (inter-CV,%). Intra-subject reproducibility was expressed as within subject coefficients of variation (intra-CV,%), and intra-class correlation coefficients (ICC). Fifteen healthy subjects were included. The inter-subject reproducibility of peak-ACh depended upon the expression of the results and ranged from 55% to 162% for LDF and from 17% to 83% for LSCI. The intra-subject reproducibility (intra-CV/ICC) of peak-ACh was reduced when assessed with LSCI compared to LDF no matter how the results were expressed and whatever the protocol used. The highest intra-subject reproducibility was found using LSCI. It was 18.7%/0.87 for a single current stimulation (expressed as cutaneous vascular conductance) and 11.4%/0.61 for multiple current stimulations (expressed as absolute value). Conclusion ACh-iontophoresis coupled with LSCI is a promising test to assess endothelial function because it is reproducible, safe, and non-invasive. N°: NCT01664572.
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Affiliation(s)
- Cyril Puissant
- Laboratory of Vascular Investigations, University Hospital, Angers, France
| | - Pierre Abraham
- Laboratory of Vascular Investigations, University Hospital, Angers, France
- Biologie Neurovasculaire et Mitochondriale Intégrée (BNMI) - Unité mixte UMR CNRS 6214/INSERM U 1083, LUNAM University, Medicine Faculty, Angers, France
| | - Sylvain Durand
- EA 4334 Motricity, Interactions, and Performance, LUNAM University, University du Maine, Le Mans, France
| | - Anne Humeau-Heurtier
- LISA – Laboratoire d'Ingénierie des Systèmes Automatisés, LUNAM University, University of Angers, Angers, France
| | - Sébastien Faure
- INSERM U1063, Stress oxydant et pathologies métaboliques (SOPAM), LUNAM University, University of Angers, Angers, France
| | - Georges Lefthériotis
- Laboratory of Vascular Investigations, University Hospital, Angers, France
- Biologie Neurovasculaire et Mitochondriale Intégrée (BNMI) - Unité mixte UMR CNRS 6214/INSERM U 1083, LUNAM University, Medicine Faculty, Angers, France
| | - Pascal Rousseau
- Biologie Neurovasculaire et Mitochondriale Intégrée (BNMI) - Unité mixte UMR CNRS 6214/INSERM U 1083, LUNAM University, Medicine Faculty, Angers, France
- Department of Plastic Surgery, University Hospital, Angers, France
| | - Guillaume Mahé
- Laboratory of Vascular Investigations, University Hospital, Angers, France
- Biologie Neurovasculaire et Mitochondriale Intégrée (BNMI) - Unité mixte UMR CNRS 6214/INSERM U 1083, LUNAM University, Medicine Faculty, Angers, France
- * E-mail:
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