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Nakata T, Shibasaki M, Nishimura Y, Kinoshita T, Hashizaki T, Kamijo YI, Kouda K, Umemoto Y, Tajima F. Quantification of catecholamine neurotransmitters released from cutaneous vasoconstrictor nerve endings in men with cervical spinal cord injury. Am J Physiol Regul Integr Comp Physiol 2023; 324:R345-R352. [PMID: 36693170 DOI: 10.1152/ajpregu.00063.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Control of cutaneous circulation is critically important to maintain thermoregulation, especially in individuals with cervical spinal cord injury (CSCI) who have no or less central thermoregulatory drive. However, the peripheral vasoconstrictor mechanism and capability have not been fully investigated after CSCI. Post- and presynaptic sensitivities of the cutaneous vasoconstrictor system were investigated in 8 CSCI and 7 sedentary able-bodied (AB) men using an intradermal microdialysis technique. Eight doses of norepinephrine (NE, 10-8 to 10-1 M) and five doses of tyramine (TY, 10-8, 10-5 to 10-2 M) were administered into the anterior right and left thigh, respectively. Endogenous catecholamines, noradrenaline, and dopamine, collected at the TY site, were determined by high-performance liquid chromatography with electrochemical detection. Regardless of vasoconstrictor agents, cutaneous vascular conductance decreased dose-dependently and responsiveness was similar between the groups (NE: Group P = 0.255, Dose P = 0.014; TY: Group P = 0.468, Dose P < 0.001), whereas the highest dose of each drug induced cutaneous vasodilation. Administration of TY promoted the release of noradrenaline and dopamine in both groups. Notably, the amount of noradrenaline released was similar between the groups (P = 0.819), although the concentration of dopamine was significantly greater in individuals with CSCI than in AB individuals (P = 0.004). These results suggest that both vasoconstrictor responsiveness and neural functions are maintained after CSCI, and dopamine in the skin is likely to induce cutaneous vasodilation.
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Affiliation(s)
- Tomonori Nakata
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | | | - Yukihide Nishimura
- Department of Rehabilitation Medicine, Iwate Medical University, Wakayama, Japan
| | - Tokio Kinoshita
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan.,Division of Rehabilitation, Wakayama Medical University Hospital, Wakayama, Japan
| | - Takamasa Hashizaki
- Division of Rehabilitation, Wakayama Medical University Hospital, Wakayama, Japan
| | - Yoshi-Ichiro Kamijo
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan.,Department of Rehabilitation Medicine, Dokkyo Medical University Saitama Medical Center, Saitama, Japan
| | - Ken Kouda
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | - Yasunori Umemoto
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
| | - Fumihiro Tajima
- Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, Japan
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Aylwin PE, Racinais S, Bermon S, Lloyd A, Hodder S, Havenith G. The use of infrared thermography for the dynamic measurement of skin temperature of moving athletes during competition; methodological issues. Physiol Meas 2021; 42. [PMID: 34320480 DOI: 10.1088/1361-6579/ac1872] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/28/2021] [Indexed: 01/28/2023]
Abstract
Objective. To investigate the use of infrared thermography (IRT) for skin temperature measurement of moving athletes during competition and its sensitivity to factors that are traditionally standardised.Approach. Thermograms were collected for 18 female athletes during the 20 km racewalk at the 2019 World Athletics Championships, with a medium-wave, cooled indium antimonide medium wave infrared band (MWIR) and a long-wave, uncooled microbolometer longwave infrared band (LWIR) infrared camera.Main results. The MWIR provided greater clarity images of motion due to a shorter exposure and response time and produced a higher percentage of acceptable images. Analysing acceptable images only, the LWIR and WMIR produced good levels of agreement, with a bias of -0.1 ± 0.6 °C in mean skin temperature for the LWIR. As the surface area of an ROI was reduced, the measured temperature became less representative of the whole ROI. Compared to measuring the whole area ROI, a single central pixel produced a bias of 0.3 ± 0.3 °C (MWIR) and 0.1 ± 0.4 °C (LWIR) whilst using the maximum and minimum temperature pixels resulted in deviations of 1.3 ± 0.4 °C and -1.1 ± 0.3 °C (MWIR) and 1.2 ± 0.3 °C and -1.3 ± 0.4 °C (LWIR). The sensitivity to air and reflected temperatures was lower for the LWIR camera, due to the higher emissivity of skin in its wavelength.Significance. IRT provides an appropriate tool for the measurement of skin temperature during real-world competition and critically during athlete motion. The cheaper LWIR camera provides a feasible alternative to the MWIR in low rate of motion scenarios, with comparable precision and sensitivity to analysis. However, the LWIR is limited when higher speeds prevent the accurate measurement and ability to capture motion.
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Affiliation(s)
- Polly E Aylwin
- Environmental Ergonomics Research Centre, Loughborough University, United Kingdom
| | | | - Stéphane Bermon
- World Athletics, Health and Science Department, Principality of Monaco, Europe.,LAMHESS, Université Côte d'Azur, France
| | - Alex Lloyd
- Environmental Ergonomics Research Centre, Loughborough University, United Kingdom
| | - Simon Hodder
- Environmental Ergonomics Research Centre, Loughborough University, United Kingdom
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough University, United Kingdom
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Wingo JE, Stone T, Ng J. Cardiovascular Drift and Maximal Oxygen Uptake during Running and Cycling in the Heat. Med Sci Sports Exerc 2021; 52:1924-1932. [PMID: 32102057 DOI: 10.1249/mss.0000000000002324] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Greater cardiovascular (CV) drift occurs during cycling compared to running in temperate conditions. CV drift also corresponds to proportional reductions in maximal oxygen uptake (V˙O2max) during heat stress. Whether exercise mode differentially affects CV drift-and accompanying declines in V˙O2max-during heat stress is uncertain. The purpose of this study was to test the hypothesis that a greater magnitude of CV drift, accompanied by a greater decrement in V˙O2max, occurs during cycling compared to running in hot conditions. METHODS 7 active men (mean ± SD; age = 25 ± 6 yr, percent body fat = 11.9% ± 2.4%) completed a control graded exercise test (GXT) on a cycle ergometer and treadmill. Then on separate, counterbalanced occasions they completed 15 or 45 min of cycling or running at 60% V˙O2max in 35°C, immediately followed by a GXT to measure V˙O2max (4 trials total). The separate 15- and 45-min trials were designed to measure CV drift and V˙O2max over the same time interval. RESULTS Heart rate increased 19% and 17% and stroke volume decreased 20% and 15% between 15 and 45 min during running and cycling, respectively, but modes were not different (all P > 0.05). Despite a 1.8°C larger core-to-skin thermal gradient during running, decrements in V˙O2peak were not different between exercise modes (95% CI for difference in change scores between 15 and 45 min: -0.2, 0.3). CONCLUSIONS CV strain (indexed as CV drift) during prolonged exercise in the heat corresponds to reduced V˙O2max, irrespective of exercise mode or the thermal gradient. As such, the upward drift in heart rate associated with CV drift reflects increased relative metabolic intensity (%V˙O2max) during prolonged cycling or running in the heat.
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Affiliation(s)
- Jonathan E Wingo
- Department of Kinesiology, The University of Alabama, Tuscaloosa, AL
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Crandall CG, Rickards CA, Johnson BD. Impact of environmental stressors on tolerance to hemorrhage in humans. Am J Physiol Regul Integr Comp Physiol 2018; 316:R88-R100. [PMID: 30517019 DOI: 10.1152/ajpregu.00235.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hemorrhage is a leading cause of death in military and civilian settings, and ~85% of potentially survivable battlefield deaths are hemorrhage-related. Soldiers and civilians are exposed to a number of environmental and physiological conditions that have the potential to alter tolerance to a hemorrhagic insult. The objective of this review is to summarize the known impact of commonly encountered environmental and physiological conditions on tolerance to hemorrhagic insult, primarily in humans. The majority of the studies used lower body negative pressure (LBNP) to simulate a hemorrhagic insult, although some studies employed incremental blood withdrawal. This review addresses, first, the use of LBNP as a model of hemorrhage-induced central hypovolemia and, then, the effects of the following conditions on tolerance to LBNP: passive and exercise-induced heat stress with and without hypohydration/dehydration, exposure to hypothermia, and exposure to altitude/hypoxia. An understanding of the effects of these environmental and physiological conditions on responses to a hemorrhagic challenge, including tolerance, can enable development and implementation of targeted strategies and interventions to reduce the impact of such conditions on tolerance to a hemorrhagic insult and, ultimately, improve survival from blood loss injuries.
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Affiliation(s)
- Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center , Dallas, Texas
| | - Caroline A Rickards
- Department of Physiology and Anatomy, University of North Texas Health Science Center , Fort Worth, Texas
| | - Blair D Johnson
- Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, New York
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Postsynaptic cutaneous vasodilation and sweating: influence of adiposity and hydration status. Eur J Appl Physiol 2018; 118:1703-1713. [PMID: 29855792 DOI: 10.1007/s00421-018-3902-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/24/2018] [Indexed: 10/14/2022]
Abstract
INTRODUCTION Obesity and hypohydration independently affect postsynaptic endothelial function, but it is unknown if hypohydration affects lean and obese individuals differently. PURPOSE To examine the effect of hypohydration on postsynaptic cutaneous vasodilation and sweating in men with high and low adiposity (HI- and LO-BF, respectively). METHODS Ten males with LO-BF and ten with HI-BF were instrumented for forearm microdialysis when euhydrated and hypohydrated. Changes in cutaneous vascular conductance (CVC) with intradermal infusion of sodium nitroprusside (SNP) and methacholine chloride (MCh) were assessed. Local sweat rate (LSR) was simultaneously assessed at the MCh site. At the end of the last dose, maximal CVC was elicited by delivering a maximal dose of SNP for 30 min to both sites with simultaneous local heating at the SNP site. The concentration of drug needed to elicit 50% of the maximal response (EC50) was compared between groups and hydration conditions. RESULTS When euhydrated, EC50 of MCh-induced CVC was not different between LO- vs. HI-BF [- 3.04 ± 0.12 vs. - 2.98 ± 0.19 log (MCh) M, P = 0.841]. EC50 of SNP-induced CVC was higher in euhydrated HI- vs. LO-BF (- 1.74 ± 0.17 vs. - 2.13 ± 0.06 log (SNP) M, P = 0.034). Within each group, hydration status did not change MCh- or SNP-induced CVC (P > 0.05). LSR was not different between groups or hydration condition (P > 0.05). CONCLUSIONS These data suggest reduced sensitivity of endothelium-independent vasodilation in individuals with high adiposity when euhydrated. However, hypohydration does not affect cutaneous vasodilation or local sweat rate differently between individuals with low or high adiposity.
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Kim K, Hurr C, Patik JC, Matthew Brothers R. Attenuated cutaneous microvascular function in healthy young African Americans: Role of intradermal l-arginine supplementation. Microvasc Res 2018; 118:1-6. [PMID: 29408444 DOI: 10.1016/j.mvr.2018.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/03/2018] [Accepted: 02/01/2018] [Indexed: 11/17/2022]
Abstract
It has been established that endothelial function in conduit vessels is reduced in young African Americans (AA) relative to Caucasian Americans (CA). However, less is known regarding endothelial function in microvasculature of young AA. We hypothesized that microvascular function in response to local heating of skin is attenuated in young AA relative to age-matched CA due largely to the lack of NO bioavailability, which is in turn improved by intradermal l-arginine supplementation and/or inhibition of arginase. Nine AA and nine CA adults participated in this study. Participants were instrumented with four microdialysis membranes in the cutaneous vasculature of one forearm and were randomly assigned to receive 1) lactated Ringer's solution as a control site; 2) 20 mM NG-nitro-l-arginine (l-NAME) to inhibit NO synthase activity; 3) 10 mM l-arginine to local supplement l-arginine; or 4) a combination of 5.0 mM (S)-(2‑boronoethyl)-l-cysteine-HCL (BEC) and 5.0 mM Nω-hydroxy-nor-l-arginine (nor-NOHA) at a rate of 2.0 μl/min to locally inhibit arginase activity. Cutaneous vascular conductance (CVC) was calculated as red blood cell flux divided by mean arterial pressure. All CVC data were presented as a percentage of maximal CVC (%CVCmax) that was determined by maximal cutaneous vasodilation induced by 44 °C heating plus sodium nitroprusside administration. The response during the 42 °C local heating plateau was blunted in the AA at the control site (CA: 84 ± 12 vs. AA: 62 ± 6 vs. %CVCmax; P < 0.001). This response was improved in AA at the l-arginine site (Control: 62 ± 6 vs. l-arginine: 70 ± 18%CVCmax; P < 0.05) but not in the arginase inhibited site (Control: 62 ± 6 vs. Arginase inhibited: 62 ± 13%CVCmax; P = 0.91). In addition, the AA group had an attenuated NO contribution to the plateau phase during 42 °C local heating relative to the CA group (CA: 56 ± 14 vs. AA: 44 ± 6 Δ %CVCmax; P < 0.001). These findings suggest that 1) cutaneous microvascular function in response to local heating is blunted in young AA when compared to age-matched young CA; 2) this attenuated response is partly related to decrease in NO bioavailability in young AA; and 3) a local infusion of l-arginine, but not arginase inhibition, improves cutaneous microvascular responses to local heating in young AA relative to CA.
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Affiliation(s)
- Kiyoung Kim
- Department of Pathology, The University of Alabama at Birmingham, United States
| | - Chansol Hurr
- Department of Pharmacology and Physiology, George Washington University, United States
| | - Jordan C Patik
- Department of Kinesiology, The University of Texas at Arlington, United States
| | - R Matthew Brothers
- Department of Kinesiology, The University of Texas at Arlington, United States.
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Stewart JM, Suggs M, Merchant S, Sutton R, Terilli C, Visintainer P, Medow MS. Postsynaptic α1-Adrenergic Vasoconstriction Is Impaired in Young Patients With Vasovagal Syncope and Is Corrected by Nitric Oxide Synthase Inhibition. Circ Arrhythm Electrophysiol 2017; 9:CIRCEP.115.003828. [PMID: 27444639 DOI: 10.1161/circep.115.003828] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 06/15/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). During VVS, gravitational pooling excessively reduces central blood volume and cardiac output. In VVS, as in hemorrhage, impaired adrenergic vasoconstriction and venoconstriction result in hypotension. We hypothesized that impaired adrenergic responsiveness because of excess nitric oxide can be reversed by reducing nitric oxide. METHODS AND RESULTS We recorded cardiopulmonary dynamics in supine syncope patients and healthy volunteers (aged 15-27 years) challenged with a dose-response using the α1-agonist phenylephrine (PE), with and without the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, monoacetate salt (L-NMMA). Systolic and diastolic pressures among control and VVS were the same, although they increased after L-NMMA and saline+PE (volume and pressor control for L-NMMA). Heart rate was significantly reduced by L-NMMA (P<0.05) for control and VVS compared with baseline, but there was no significant difference in heart rate between L-NMMA and saline+PE. Cardiac output and splanchnic blood flow were reduced by L-NMMA for control and VVS (P<0.05) compared with baseline, while total peripheral resistance increased (P<0.05). PE dose-response for splanchnic flow and resistance were blunted for VVS compared with control after saline+PE, but enhanced after L-NMMA (P<0.001). Postsynaptic α1-adrenergic vasoconstrictive impairment was greatest in the splanchnic vasculature, and splanchnic blood flow was unaffected by PE. Forearm and calf α1-adrenergic vasoconstriction were unimpaired in VVS and unaffected by L-NMMA. CONCLUSIONS Impaired postsynaptic α1-adrenergic vasoconstriction in young adults with VVS can be corrected by nitric oxide synthase inhibition, demonstrated with our use of L-NMMA.
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Affiliation(s)
- Julian M Stewart
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
| | - Melissa Suggs
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Sana Merchant
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Richard Sutton
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Courtney Terilli
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Paul Visintainer
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Marvin S Medow
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
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Matsusue A, Ishikawa T, Michiue T, Waters B, Hara K, Kashiwagi M, Takayama M, Ikematsu N, Kubo SI. Association between cerebrospinal fluid dopamine concentrations and catechol- O -methyltransferase gene polymorphisms in forensic autopsy cases of methamphetamine abusers. Forensic Sci Int 2017; 270:159-164. [DOI: 10.1016/j.forsciint.2016.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 11/07/2016] [Accepted: 12/03/2016] [Indexed: 11/25/2022]
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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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Nybo L, Rasmussen P, Sawka MN. Performance in the heat-physiological factors of importance for hyperthermia-induced fatigue. Compr Physiol 2014; 4:657-89. [PMID: 24715563 DOI: 10.1002/cphy.c130012] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This article presents a historical overview and an up-to-date review of hyperthermia-induced fatigue during exercise in the heat. Exercise in the heat is associated with a thermoregulatory burden which mediates cardiovascular challenges and influence the cerebral function, increase the pulmonary ventilation, and alter muscle metabolism; which all potentially may contribute to fatigue and impair the ability to sustain power output during aerobic exercise. For maximal intensity exercise, the performance impairment is clearly influenced by cardiovascular limitations to simultaneously support thermoregulation and oxygen delivery to the active skeletal muscle. In contrast, during submaximal intensity exercise at a fixed intensity, muscle blood flow and oxygen consumption remain unchanged and the potential influence from cardiovascular stressing and/or high skin temperature is not related to decreased oxygen delivery to the skeletal muscles. Regardless, performance is markedly deteriorated and exercise-induced hyperthermia is associated with central fatigue as indicated by impaired ability to sustain maximal muscle activation during sustained contractions. The central fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but inhibitory signals from thermoreceptors arising secondary to the elevated core, muscle and skin temperatures and augmented afferent feedback from the increased ventilation and the cardiovascular stressing (perhaps baroreceptor sensing of blood pressure stability) and metabolic alterations within the skeletal muscles are likely all factors of importance for afferent feedback to mediate hyperthermia-induced fatigue during submaximal intensity exercise. Taking all the potential factors into account, we propose an integrative model that may help understanding the interplay among factors, but also acknowledging that the influence from a given factor depends on the exercise hyperthermia situation.
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Affiliation(s)
- Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Denmark
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Ishikawa T, Inamori-Kawamoto O, Quan L, Michiue T, Chen JH, Wang Q, Zhu BL, Maeda H. Postmortem urinary catecholamine levels with regard to the cause of death. Leg Med (Tokyo) 2014; 16:344-9. [DOI: 10.1016/j.legalmed.2014.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/25/2014] [Accepted: 07/21/2014] [Indexed: 01/15/2023]
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Esen H, Ata N, Esen F. Transitions in skin blood flow fractal scaling: the importance of fluctuation amplitude in microcirculation. Microvasc Res 2014; 97:6-12. [PMID: 25241251 DOI: 10.1016/j.mvr.2014.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/10/2014] [Accepted: 07/30/2014] [Indexed: 11/29/2022]
Abstract
Detrended fluctuation analysis (DFA) of laser Doppler flowmetry (LDF) time series from volar skin reveals three scaling regions: cardiac, cardio-respiratory and local. Scaling exponents, slopes (αC, αCR and αL) of the straight lines, in these regions indicate correlation properties of LDF signal. Transitions from uncorrelated to positive in cardiac (αC) and positive to negative correlations in the cardio-respiratory (αCR) exponent have been observed for vasodilatation signals in response to local heating. However, positive correlation in local region (αL) did not change with vasodilatation. We studied whether the transitions in scaling exponents are correlated with the increase in peak to peak fluctuation amplitude (AF) of LDF signal. LDF signals were normalized to unity using average values of their pulsatile parts: baseline and saturation signals. If AF of normalized LDF signal is ≥0.5, we observed transitions in αC and in αCR but not in αL, in healthy subjects. It is suggested that the transition from positive to negative correlation in αCR with increasing amplitude may be explained by intact arteriolar myogenic activity in healthy young (Y) and middle aged (MA) subjects. In contrast, we did not observe transition in αCR suggesting impaired myogenic activity in patients with essential hypertension (EHT).
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Affiliation(s)
- Hamza Esen
- Department of Biophysics, Faculty of Medicine, Eskişehir Osmangazi University, 26480 Eskişehir, Turkey.
| | - Necmi Ata
- Department of Biophysics, Faculty of Medicine, Eskişehir Osmangazi University, 26480 Eskişehir, Turkey
| | - Ferhan Esen
- Department of Biophysics, Faculty of Medicine, Eskişehir Osmangazi University, 26480 Eskişehir, Turkey
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Wilson TE, Klabunde RE, Monahan KD. Using thermal stress to model aspects of disease states. J Therm Biol 2014; 43:24-32. [DOI: 10.1016/j.jtherbio.2014.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 03/14/2014] [Accepted: 03/21/2014] [Indexed: 10/25/2022]
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Ishikawa T, Quan L, Michiue T, Kawamoto O, Wang Q, Chen JH, Zhu BL, Maeda H. Postmortem catecholamine levels in pericardial and cerebrospinal fluids with regard to the cause of death in medicolegal autopsy. Forensic Sci Int 2013; 228:52-60. [DOI: 10.1016/j.forsciint.2013.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 01/30/2013] [Accepted: 02/04/2013] [Indexed: 01/19/2023]
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Kenney WL, Stanhewicz AE, Bruning RS, Alexander LM. Blood pressure regulation III: what happens when one system must serve two masters: temperature and pressure regulation? Eur J Appl Physiol 2013; 114:467-79. [PMID: 23636697 DOI: 10.1007/s00421-013-2652-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/19/2013] [Indexed: 11/25/2022]
Abstract
When prolonged intense exercise is performed at high ambient temperatures, cardiac output must meet dual demands for increased blood flow to contracting muscle and to the skin. The literature has commonly painted this scenario as a fierce competition, wherein one circulation preserves perfusion at the expense of the other, with the regulated maintenance of blood pressure as the ultimate goal. This review redefines this scenario as commensalism, an integrated balance of regulatory control where one circulation benefits with little functional effect on the other. In young, healthy subjects, arterial pressure rarely falls to any great extent during either extreme passive heating or prolonged dynamic exercise in the heat, nor does body temperature rise disproportionately due to a compromised skin blood flow. Rather, it often takes the superimposition of additional stressors--e.g., dehydration or simulated hemorrhage--upon heat stress to substantially impact blood pressure regulation.
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Affiliation(s)
- W Larry Kenney
- Department of Kinesiology and Physiology Program, The Pennsylvania State University, 102 Noll Laboratory, University Park, PA, 16802-6900, USA,
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Wenner MM, Wilson TE, Davis SL, Stachenfeld NS. Pharmacological curve fitting to analyze cutaneous adrenergic responses. J Appl Physiol (1985) 2011; 111:1703-9. [PMID: 21868682 DOI: 10.1152/japplphysiol.00780.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although dose-response curves are commonly used to describe in vivo cutaneous α-adrenergic responses, modeling parameters and analyses methods are not consistent across studies. The goal of the present investigation was to compare three analysis methods for in vivo cutaneous vasoconstriction studies using one reference data set. Eight women (22 ± 1 yr, 24 ± 1 kg/m(2)) were instrumented with three cutaneous microdialysis probes for progressive norepinephrine (NE) infusions (1 × 10(-8), 1 × 10(-6), 1 × 10(-5), 1 × 10(-4), and 1 × 10(-3) logM). NE was infused alone, co-infused with NG-monomethyl-l-arginine (l-NMMA, 10 mM) or Ketorolac tromethamine (KETO, 10 mM). For each probe, dose-response curves were generated using three commonly reported analyses methods: 1) nonlinear modeling without data manipulation, 2) nonlinear modeling with data normalization and constraints, and 3) percent change from baseline without modeling. Not all data conformed to sigmoidal dose-response curves using analysis 1, whereas all subjects' curves were modeled using analysis 2. When analyzing only curves that fit the sigmoidal model, NE + KETO induced a leftward shift in ED(50) compared with NE alone with analyses 1 and 2 (F test, P < 0.05) but only tended to shift the response leftward with analysis 3 (repeated-measures ANOVA, P = 0.08). Neither maximal vasoconstrictor capacity (E(max)) in analysis 1 nor %change CVC change from baseline in analysis 3 were altered by blocking agents. In conclusion, although the overall detection of curve shifts and interpretation was similar between the two modeling methods of curve fitting, analysis 2 produced more sigmoidal curves.
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FARNEBO SIMON, ZETTERSTEN ERIKK, SAMUELSSON ANDERS, TESSELAAR ERIK, SJÖBERG FOLKE. Assessment of Blood Flow Changes in Human Skin by Microdialysis Urea Clearance. Microcirculation 2011; 18:198-204. [DOI: 10.1111/j.1549-8719.2010.00077.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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HENRICSON JOAKIM, TESSELAAR ERIK, BAIAT YASHMA, NILSSON GERT, SJÖBERG FOLKE. Local Heating as a Predilatation Method for Measurement of Vasoconstrictor Responses with Laser-Doppler Flowmetry. Microcirculation 2011; 18:214-20. [DOI: 10.1111/j.1549-8719.2010.00079.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Crandall CG, Shibasaki M, Wilson TE. Insufficient cutaneous vasoconstriction leading up to and during syncopal symptoms in the heat stressed human. Am J Physiol Heart Circ Physiol 2010; 299:H1168-73. [PMID: 20693394 DOI: 10.1152/ajpheart.00290.2010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As much as 50% of cardiac output can be distributed to the skin in the hyperthermic human, and therefore the control of cutaneous vascular conductance (CVC) becomes critical for the maintenance of blood pressure. Little is known regarding the magnitude of cutaneous vasoconstriction in profoundly hypotensive individuals while heat stressed. This project investigated the hypothesis that leading up to and during syncopal symptoms associated with combined heat and orthostatic stress, reductions in CVC are inadequate to prevent syncope. Using a retrospective study design, we evaluated data from subjects who experienced syncopal symptoms during lower body negative pressure (N = 41) and head-up tilt (N = 5). Subjects were instrumented for measures of internal temperature, forearm skin blood flow, arterial pressure, and heart rate. CVC was calculated as skin blood flow/mean arterial pressure × 100. Data were obtained while subjects were normothermic, immediately before an orthostatic challenge while heat stressed, and at 5-s averages for the 2 min preceding the cessation of the orthostatic challenge due to syncopal symptoms. Whole body heat stress increased internal temperature (1.25 ± 0.3°C; P < 0.001) and CVC (29 ± 20 to 160 ± 58 CVC units; P < 0.001) without altering mean arterial pressure (83 ± 7 to 82 ± 6 mmHg). Mean arterial pressure was reduced to 57 ± 9 mmHg (P < 0.001) immediately before the termination of the orthostatic challenge. At test termination, CVC decreased to 138 ± 61 CVC units (P < 0.001) relative to before the orthostatic challenge but remained approximately fourfold greater than when subjects were normothermic. This negligible reduction in CVC during pronounced hypotension likely contributes to reduced orthostatic tolerance in heat-stressed humans. Given that lower body negative pressure and head-up tilt are models of acute hemorrhage, these findings have important implications with respect to mechanisms of compromised blood pressure control in the hemorrhagic individual who is also hyperthermic (e.g., military personnel, firefighters, etc.).
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Affiliation(s)
- C G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX 75231, USA.
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Johnson JM, Kellogg DL. Local thermal control of the human cutaneous circulation. J Appl Physiol (1985) 2010; 109:1229-38. [PMID: 20522732 DOI: 10.1152/japplphysiol.00407.2010] [Citation(s) in RCA: 185] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The level of skin blood flow is subject to both reflex thermoregulatory control and influences from the direct effects of warming and cooling the skin. The effects of local changes in temperature are capable of maximally vasoconstricting or vasodilating the skin. They are brought about by a combination of mechanisms involving endothelial, adrenergic, and sensory systems. Local warming initiates a transient vasodilation through an axon reflex, succeeded by a plateau phase due largely to nitric oxide. Both phases are supported by sympathetic transmitters. The plateau phase is followed by the die-away phenomenon, a slow reversal of the vasodilation that is dependent on intact sympathetic vasoconstrictor nerves. The vasoconstriction with local skin cooling is brought about, in part, by a postsynaptic upregulation of α(2c)-adrenoceptors and, in part, by inhibition of the nitric oxide system at at least two points. There is also an early vasodilator response to local cooling, dependent on the rate of cooling. The mechanism for that transient vasodilation is not known, but it is inhibited by intact sympathetic vasoconstrictor nerve function and by intact sensory nerve function.
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Affiliation(s)
- John M Johnson
- Dept. of Physiology, Univ. of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio TX 78231, USA.
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Wingo JE, Brothers RM, Del Coso J, Crandall CG. Intradermal administration of ATP does not mitigate tyramine-stimulated vasoconstriction in human skin. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1417-20. [PMID: 20237299 DOI: 10.1152/ajpregu.00846.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cutaneous vasodilation associated with whole-body heat stress occurs via withdrawal of adrenergic vasoconstriction and engagement of cholinergic "active" vasodilation, the latter of which attenuates cutaneous vasoconstrictor responsiveness. However, the precise neurotransmitter(s) responsible for this sympatholytic-like effect remain unknown. In skeletal muscle, ATP inhibits adrenergically mediated vasoconstriction. ATP also may be responsible for attenuating cutaneous vasoconstriction since it is co-released from cholinergic neurons. The effect of ATP on cutaneous vasoconstrictor responsiveness, however, has not been investigated. Accordingly, this study tested the hypothesis that ATP inhibits adrenergically mediated cutaneous vasoconstriction. To accomplish this objective, four microdialysis probes were inserted in dorsal forearm skin of 11 healthy individuals (mean +/- SD; 35 +/- 11 years). Local temperature at each site was clamped at 34 degrees C throughout the protocol. Skin blood flow was indexed by laser-Doppler flowmetry and was used to calculate cutaneous vascular conductance (CVC; laser-Doppler-derived flux/mean arterial pressure), which was normalized to peak CVC achieved with sodium nitroprusside infusion combined with local skin heating to approximately 42 degrees C. Two membranes were perfused with 30 mM ATP, while the other two membranes were flow matched via administration of 2.8 mM adenosine to serve as control sites. After achieving stable baselines, 1 x 10(-4) M tyramine was administered at all sites, while ATP and adenosine continued to be infused at their respective sites. ATP and adenosine infusion increased CVC from baseline by 35 +/- 26% CVC(peak) units and by 36 +/- 15% CVC(peak) units, respectively (P = 0.75). Tyramine decreased CVC similarly (by about one-third) at all sites (P < 0.001 for main effect and P = 0.32 for interaction). These findings indicate that unlike in skeletal muscle, ATP does not attenuate tyramine-stimulated vasoconstriction in human skin.
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Affiliation(s)
- Jonathan E Wingo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Ave., Dallas, TX 75231, USA
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