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Trbovich M, Wu Y, Koek W, Zhao J, Kellogg D. Impact of tetraplegia vs. paraplegia on venoarteriolar, myogenic and maximal cutaneous vasodilation responses of the microvasculature: Implications for cardiovascular disease. J Spinal Cord Med 2022; 45:49-57. [PMID: 32496962 PMCID: PMC8890560 DOI: 10.1080/10790268.2020.1761173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Objective: Cardiovascular disease (CVD) is a leading cause of mortality in persons with SCI. While macrovascular remodeling and function after SCI is well documented, changes in the microvascular structure and function are comparably understudied, but importantly predict CVD risk. Specifically, the integrity of venoarteriolar (VAR), myogenic (MYO) and maximal vasodilation responses are largely unknown after SCI, especially in persons with tetraplegia (TP) at highest risk of CVD. This is the first to examine the differences in VAR (cuff inflation), MYO (limb dependency) and maximal vasodilation responses of the microvasculature between able bodied (AB) versus those with TP and paraplegia (PP).Design: Observational.Setting: Laboratory.Participants: Eight AB, 6 TP, and 8 PP persons.Interventions: One forearm and calf were treated topically with lidocaine 2.5%/prilocaine 2.5% while contralateral limb served as a control. Laser doppler flowmeters were applied over treated and control sites during limb dependency, cuff inflation and local skin heating (Tloc) up to 42°C.Outcome measures: Skin vascular resistance (SkVR) change with cuff inflation and limb dependency and maximal cutaneous vascular conductance (CVC) during local heating.Results: Change in SkVR was not significantly different between groups or extremity (upper vs. lower) during cuff inflation or limb dependency. However, CVC at Tloc 42°C was significantly different in the lower extremity (LE) of TP and PP (P = 0.007, 0.35) compared to AB.Conclusion: Increases in SkVR during cuff inflation (VAR) and limb dependency (VAR and MYO) are unaltered after SCI, however maximal vasodilation in the LE post-SCI is higher than AB persons.
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Affiliation(s)
- Michelle Trbovich
- Department of Rehabilitation Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,Correspondence to: Michelle Trbovich, Department of Rehabilitation Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio78229, TX, USA.
| | - Yubo Wu
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Wouter Koek
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Joan Zhao
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Dean Kellogg
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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2
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Kish B, Herr S, Yang HCS, Sun S, Shi R, Tong Y. Whole body measurements using near-infrared spectroscopy in a rat spinal cord contusion injury model. J Spinal Cord Med 2021; 46:508-520. [PMID: 33890843 PMCID: PMC10116927 DOI: 10.1080/10790268.2021.1911504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Spinal cord injuries cause great damage to the central nervous system as well as the peripheral vasculature. While treatments for spinal cord injury typically focus on the spine itself, improvements in the function of the peripheral vasculature after spinal cord injury have shown to improve overall neurological recovery. OBJECTIVE This study focused on the use of near-infrared spectroscopy (NIRS) as a mode to monitor cerebral and peripheral vascular condition non-invasively during the recovery process. DESIGN Animal research study. METHODS Rats underwent spinal contusion or sham injury and relative concentrations of de-/oxyhemoglobin (Δ[HbO]/Δ[Hb]) over time were measured over the cerebral, spinal, and pedal regions via NIRS. Correlational relationships across the body were determined. Rats received 1 NIRS measurement before injury and 3 after injury: 4, 7, and 14 days post. RESULTS Correlational relationships between signals across the body, between animals with and without spinal cord injury, indicate that NIRS was able to detect patterns of vascular change in the spine and the periphery occurring secondary to spinal cord injury and evolving during subsequent recovery. Additionally, NIRS determined an overall correlational decrease within the central nervous system, between spinal and cerebral measurements. CONCLUSION NIRS was able to closely reflect physiologic changes in the rat during recovery, demonstrating a promising method to monitor whole body hemodynamics after spinal cord injury.
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Affiliation(s)
- Brianna Kish
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Seth Herr
- Center for Paralysis Research and Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - Ho-Ching Shawn Yang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Siyuan Sun
- Center for Paralysis Research and Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - Riyi Shi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA.,Center for Paralysis Research and Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - Yunjie Tong
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
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Itoh M, Endo MY, Hojo T, Yoshimura M, Fukuoka Y. Characteristics of cardiovascular responses to an orthostatic challenge in trained spinal cord-injured individuals. J Physiol Anthropol 2018; 37:22. [PMID: 30268154 PMCID: PMC6162881 DOI: 10.1186/s40101-018-0182-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 09/13/2018] [Indexed: 11/22/2022] Open
Abstract
Background We investigated cardiovascular responses to an orthostatic challenge in trained spinal cord-injured (SCI) individuals compared to able-bodied (AB) individuals. Methods A total of 23 subjects participated, divided into three groups: seven were trained as spinal cord-injured (Tr-SCI) individuals, seven were able-bodied individuals trained as runners (Tr-AB), and nine were untrained able-bodied individuals (UnTr-AB). We measured the cardiovascular autonomic responses in all three groups during each 5-min head-up tilt (HUT) of 0°, 40°, and 80°. Stroke volume (SV), heart rate (HR), and cardiac output (Qc) as cardiovascular responses were measured by impedance cardiography. Changes in deoxyhemoglobin (∆[HHb]) and total hemoglobin (∆[Hbtot]) concentrations of the right medial gastrocnemius muscle were measured using near-infrared spectroscopy (NIRS). Results As the HUT increased from 0° to 80°, Tr-SCI group showed less change in SV at all HUT levels even if HR increased significantly. Mean arterial pressure (MAP) also did not significantly increase as tilting increased from 0° to 80°. Regarding peripheral vascular responses, the alterations of ∆[Hbtot] from 0° to 80° were less in Tr-SCI group compared to AB individuals. Conclusion There is a specific mechanism whereby blood pressure is maintained during a HUT in Tr-SCI group with the elicitation of peripheral vasoconstriction and the atrophy of the vascular vessels in paraplegic lower limbs, which would be associated with less change in SV in response to an orthostatic challenge.
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Affiliation(s)
- Masahiro Itoh
- Department of Physiology, Kumamoto University Graduate School of Life Sciences, 4-24-1, Kuhonji Chuou-ku, Kumamoto, 862-0976, Japan.
| | - Masako Yamaoka Endo
- Department of Exercise Science and Physiology, Faculty of Human Culture and Science, Prefectural University of Hiroshima, Hiroshima, Japan.,Laboratory of Environmental Physiology, Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto, Japan
| | - Tatsuya Hojo
- Laboratory of Sports Medicine, Faculty of Health and Sport Science, Doshisha University, Kyoto, Japan
| | - Miho Yoshimura
- Laboratory of Sports Medicine, Faculty of Health and Sport Science, Doshisha University, Kyoto, Japan
| | - Yoshiyuki Fukuoka
- Laboratory of Environmental Physiology, Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto, Japan.,Laboratory of Environmental Physiology, Faculty of Health and Sport Science, Doshisha University, Kyoto, Japan
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Lujan HL, DiCarlo SE. Fundamental hemodynamic mechanisms mediating the response to myocardial ischemia in conscious paraplegic mice: cardiac output versus peripheral resistance. Physiol Rep 2017; 5:5/6/e13214. [PMID: 28336819 PMCID: PMC5371571 DOI: 10.14814/phy2.13214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/21/2017] [Accepted: 02/22/2017] [Indexed: 11/25/2022] Open
Abstract
Autonomic dysfunction, a relative sedentary lifestyle, a reduced muscle mass and increased adiposity leads to metabolic abnormalities that accelerate the development of coronary artery disease (CAD) in individuals living with spinal cord injury (SCI). An untoward cardiac incident is related to the degree of CAD, suggesting that the occurrence of a significant cardiac event is significantly higher for individuals with SCI. Thus, understanding the fundamental hemodynamic mechanisms mediating the response to myocardial ischemia has the potential to positively impact individuals and families living with SCI. Accordingly, we systematically investigated if thoracic level 5 spinal cord transection (T5X; paraplegia) alters the arterial blood pressure response to coronary artery occlusion and if the different arterial blood pressure responses to coronary artery occlusion between intact and paraplegic mice are mediated by changes in cardiac output and or systemic peripheral resistance and whether differences in cardiac output are caused by changes in heart rate and or stroke volume. To achieve this goal, the tolerance to 3 min of coronary artery occlusion was determined in conscious intact and paraplegic mice. Paraplegic mice had an impaired ability to maintain arterial blood pressure during coronary artery occlusion as arterial pressure fell to near lethal levels by 1.38 ± 0.64 min. The lower arterial pressure was mediated by a lower cardiac output as systemic peripheral resistance was elevated in paraplegic mice. The lower cardiac output was mediated by a reduced heart rate and stroke volume. These results indicate that in paraplegic mice, the arterial pressure response to coronary artery occlusion is hemodynamically mediated primarily by cardiac output which is determined by heart rate and stroke volume.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Al Dera H, Brock JA. Changes in sympathetic neurovascular function following spinal cord injury. Auton Neurosci 2017; 209:25-36. [PMID: 28209424 DOI: 10.1016/j.autneu.2017.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/31/2017] [Accepted: 02/09/2017] [Indexed: 12/31/2022]
Abstract
The effects of spinal cord injury (SCI) on sympathetic neurovascular transmission have generally been ignored. This review describes changes in sympathetic nerve-mediated activation of arterial vessels to which ongoing sympathetic activity has been reduced or silenced following spinal cord transection in rats. In all vessels studied in rats, SCI markedly enhanced their contractile responses to nerve activity. However, the mechanisms that augment neurovascular transmission differ between the rat tail artery and mesenteric artery. In tail artery, the enhancement of neurovascular transmission cannot be attributed to changes in sensitivity of the vascular muscle to α1- or α2-adrenoceptor agonists. Instead the contribution of L-type Ca2+ channels to activation of the smooth muscle by nerve-released noradrenaline is greatly increased following SCI. By contrast, mesenteric arteries from SCI rats had increased sensitivity to phenylephrine but not to methoxamine. While both phenylephrine and methoxamine are α1-adrenoceptor agonists, only phenylephrine is a substrate for the neuronal noradrenaline transporter. Therefore the selective increase in sensitivity to phenylephrine suggests that the activity of the neuronal noradrenaline transporter is reduced. While present evidence suggests that sympathetic vasoconstrictor neurons do not contribute to the normal regulation of peripheral resistance below a complete SCI in humans, the available evidence does indicate that these experimental findings in animals are likely to apply after SCI in humans and contribute to autonomic dysreflexia.
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Affiliation(s)
- Hussain Al Dera
- Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - James A Brock
- Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia.
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Rianne Ravensbergen HJ, de Groot S, Post MW, Bongers-Janssen HM, van der Woude LH, Claydon VE. Is There an Association Between Markers of Cardiovascular Autonomic Dysfunction at Discharge From Rehabilitation and Participation 1 and 5 Years Later in Individuals With Spinal Cord Injury? Arch Phys Med Rehabil 2016; 97:1431-1439. [PMID: 27084265 DOI: 10.1016/j.apmr.2016.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 03/14/2016] [Accepted: 03/19/2016] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine whether physical activity and participation 1 and 5 years after discharge are associated with measures of cardiovascular autonomic function: prevalence of hypotension and reduced peak heart rate at discharge from initial inpatient spinal cord injury (SCI) rehabilitation. DESIGN Prospective cohort study. SETTING Rehabilitation centers. PARTICIPANTS Individuals with SCI (N=146). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES We recorded markers of cardiovascular autonomic dysfunction (resting blood pressure and peak heart rate) and personal and lesion characteristics at the time of discharge from rehabilitation. Parameters for participation (social health status dimension of the Sickness Impact Profile) and physical activity (Physical Activity Scale for Individuals with Physical Disabilities [PASIPD]) were measured 1 and 5 years after discharge. Effects of prevalence of cardiovascular autonomic dysfunction were analyzed using linear regression analysis while correcting for possible confounders. RESULTS We found no significant association between hypotension and social health status dimension of the Sickness Impact Profile or PASIPD, either at 1 or at 5 years after discharge. A significant association between peak heart rate and social health status dimension of the Sickness Impact Profile was found at 1 year after discharge, showing poorer participation in individuals with low peak heart rate (ie, cardiovascular autonomic dysfunction). The unadjusted relation between peak heart rate and the social health status dimension of the Sickness Impact Profile was significant at 5 years, but not when adjusted for confounders. We found associations between peak heart rate and PASIPD for both 1 and 5 years after discharge; however, these were not significant after correction for potential confounding factors. CONCLUSIONS Autonomic dysfunction after SCI is a crucial factor influencing quality of life. We found that cardiovascular autonomic impairment, assessed from low peak heart rate, was associated with reduced participation after 1 year. The results suggest that peak heart rate at discharge from rehabilitation after SCI should be used to identify those needing additional support to facilitate physical activity and participation after discharge.
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Affiliation(s)
- H J Rianne Ravensbergen
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada; International Collaboration On Repair Discoveries, Vancouver, BC, Canada; Research Institute MOVE Amsterdam, Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands
| | - Sonja de Groot
- Amsterdam Rehabilitation Research Center
- Reade, Amsterdam, The Netherlands; Center for Human Movement Sciences Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marcel W Post
- Brain Center Rudolf Magnus and Center of Excellence in Rehabilitation Medicine, University Medical Center Utrecht and De Hoogstraat, Utrecht, The Netherlands; Center for Rehabilitation, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Lucas H van der Woude
- Center for Human Movement Sciences Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Center for Rehabilitation, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada; International Collaboration On Repair Discoveries, Vancouver, BC, Canada.
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7
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Protheroe CL, Ravensbergen HRJC, Inskip JA, Claydon VE. Tilt testing with combined lower body negative pressure: a "gold standard" for measuring orthostatic tolerance. J Vis Exp 2013:e4315. [PMID: 23542558 DOI: 10.3791/4315] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT(1). In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope(2). Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes(2-6). Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance(7). Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients(2-6). However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity(8,9). Thus, different methods were explored to increase the orthostatic stress and improve sensitivity. Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline(4,7,10,11) or sublingual nitrate(12,13). However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity(10,14), with a high positive response rate immediately after administration(15). Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate(1). Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s(16-18). This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1±0.6 min(16,17). This allows not only diagnosis and pathophysiological assessment(19-22), but also the evaluation of treatments for orthostatic intolerance due to its high repeatability(23-30). For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.
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Affiliation(s)
- Clare L Protheroe
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
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8
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Villar R, Hughson RL. Effect of altered arterial perfusion pressure on vascular conductance and muscle blood flow dynamic response during exercise in humans. J Appl Physiol (1985) 2013; 114:620-7. [DOI: 10.1152/japplphysiol.01094.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in vascular conductance (VC) are required to counter changes in muscle perfusion pressure (MPP) to maintain muscle blood flow (MBF) during exercise. We investigated the recruitment of VC as a function of peak VC measured in three body positions at two different work rates to test the hypothesis that adaptations in VC compensated changes in MPP at low-power output (LPO), but not at high-power output (HPO). Eleven healthy volunteers exercised at LPO and HPO (repeated plantar flexion contractions at 20–30% maximal voluntary contraction, respectively) in horizontal (HOR), 35° head-down tilt (HDT), and 45° head-up tilt (HUT). Muscle blood flow velocity and popliteal diameter were measured by ultrasound to determine MBF, and VC was estimated by dividing MBF flow by MPP. Peak VC was unaffected by body position. The rates of increase in MBF and VC were significantly faster in HUT and slower in HDT than HOR, and rates were faster in LPO than HPO. During LPO exercise, the increase in, and steady-state values of, MBF were less for HUT and HDT than HOR; the increase in VC was less in HUT than HOR and HDT. During HPO exercise, MBF in the HDT was reduced compared with HOR and HUT, even though VC reached 92% VC peak, which was greater than HOR, which was, in turn, greater than HUT. Reduced MBF during HPO HDT exercise had the functional consequence of a significant increase in muscle electromyographic index, revealing the effects of MPP on O2 delivery during exercise.
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Affiliation(s)
- Rodrigo Villar
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada; and
- Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Brasilia, Brazil
| | - Richard L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada; and
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West CR, AlYahya A, Laher I, Krassioukov A. Peripheral vascular function in spinal cord injury: a systematic review. Spinal Cord 2012. [DOI: 10.1038/sc.2012.136] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Villar R, Hughson RL. Lower limb vascular conductance and resting popliteal blood flow during head-up and head-down postural challenges. Clin Physiol Funct Imaging 2012; 33:186-91. [PMID: 23522011 DOI: 10.1111/cpf.12008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
Affiliation(s)
| | - Richard L. Hughson
- Faculty of Applied Health Sciences; University of Waterloo; Waterloo; ON; Canada
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West CR, Mills P, Krassioukov AV. Influence of the neurological level of spinal cord injury on cardiovascular outcomes in humans: a meta-analysis. Spinal Cord 2012; 50:484-92. [DOI: 10.1038/sc.2012.17] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Groothuis JT, Thijssen DHJ, Lenders JWM, Deinum J, Hopman MTE. Leg vasoconstriction during head-up tilt in patients with autonomic failure is not abolished. J Appl Physiol (1985) 2011; 110:416-22. [PMID: 21127209 DOI: 10.1152/japplphysiol.01098.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maintaining blood pressure during orthostatic challenges is primarily achieved by baroreceptor-mediated activation of the sympathetic nervous system, which can be divided into preganglionic and postganglionic parts. Despite their preganglionic autonomic failure, spinal cord-injured individuals demonstrate a preserved peripheral vasoconstriction during orthostatic challenges. Whether this also applies to patients with postganglionic autonomic failure is unknown. Therefore, we assessed leg vasoconstriction during 60° head-up tilt in five patients with pure autonomic failure (PAF) and two patients with autonomic failure due to dopamine-β-hydroxylase (DBH) deficiency. Ten healthy subjects served as controls. Leg blood flow was measured using duplex ultrasound in the right superficial femoral artery. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. DBH-deficient patients were tested off and on the norepinephrine pro-drug l-threo-dihydroxyphenylserine (l-DOPS). During 60° head-up tilt, leg vascular resistance increased significantly in PAF patients [0.40 ± 0.38 (+30%) mmHg·ml−1·min−1]. The increase in leg vascular resistance was not significantly different from controls [0.88 ± 1.04 (+72%) mmHg·ml−1·min−1]. In DBH-deficient patients, leg vascular resistance increased by 0.49 ± 0.01 (+153%) and 1.52 ± 1.47 (+234%) mmHg·ml−1·min−1 off and on l-DOPS, respectively. Despite the increase in leg vascular resistance, orthostatic hypotension was present in PAF and DBH-deficient patients. Our results demonstrate that leg vasoconstriction during orthostatic challenges in patients with PAF or DBH deficiency is not abolished. This indicates that the sympathetic nervous system is not the sole or pivotal mechanism inducing leg vasoconstriction during orthostatic challenges. Additional vasoconstrictor mechanisms may compensate for the loss in sympathetic nervous system control.
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Affiliation(s)
- Jan T. Groothuis
- Departments of 1Physiology and
- Department of Rehabilitation, Sint Maartenskliniek, Nijmegen, The Netherlands
| | - Dick H. J. Thijssen
- Departments of 1Physiology and
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; and
| | - Jacques W. M. Lenders
- Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen
- Department of Medicine III, Carl Gustav Carus University Medical Center, Dresden, Germany
| | - Jaap Deinum
- Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen
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Groothuis JT, Rongen GA, Geurts AC, Smits P, Hopman MT. Effect of different sympathetic stimuli-autonomic dysreflexia and head-up tilt-on leg vascular resistance in spinal cord injury. Arch Phys Med Rehabil 2011; 91:1930-5. [PMID: 21112436 DOI: 10.1016/j.apmr.2010.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/19/2010] [Accepted: 09/01/2010] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To compare the effect of different sympathetic stimuli, that is, exaggerated sympathetic activity and orthostatic challenges, on the increase in leg vascular resistance in persons with spinal cord injury (SCI) without and controls with supraspinal sympathetic control. DESIGN Case-control intervention study. SETTING Physiology research laboratory. PARTICIPANTS Persons with SCI (N=9; motor and sensory complete spinal cord lesion above the sixth thoracic spinal segment) and able-bodied controls (N=9). INTERVENTIONS In persons with SCI, exaggerated sympathetic activity was evoked by autonomic dysreflexia, and in controls, by using a cold pressor test (CPT). A 30° head-up tilt (HUT) was performed in both groups. MAIN OUTCOME MEASURE Leg blood flow was measured by using venous occlusion plethysmography during the different sympathetic stimuli. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. RESULTS In persons with SCI, leg vascular resistance significantly increased during autonomic dysreflexia and 30° HUT (25±20 and 24±13 arbitrary units [AU], respectively), with no difference (P=.87) between stimuli. In controls, leg vascular resistance significantly increased during CPT and 30° HUT (15±13 and 29±12AU, respectively) with no difference (P=.03) between stimuli. There were no differences (P=.22) in increase in leg vascular resistance during the different sympathetic stimuli between persons with SCI and controls. CONCLUSIONS The increase in leg vascular resistance during autonomic dysreflexia in persons with SCI is not different from that during 30° HUT, which might be caused by a limited vasoconstrictor reserve. Despite the lack of supraspinal sympathetic control in persons with SCI, the increase in leg vascular resistance during exaggerated sympathetic activity was not different from controls.
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Affiliation(s)
- Jan T Groothuis
- Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands
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14
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Angiotensin II contributes to the increased baseline leg vascular resistance in spinal cord-injured individuals. J Hypertens 2010; 28:2094-101. [DOI: 10.1097/hjh.0b013e32833cd2f4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brothers RM, Wingo JE, Hubing KA, Del Coso J, Crandall CG. Effect of whole body heat stress on peripheral vasoconstriction during leg dependency. J Appl Physiol (1985) 2009; 107:1704-9. [PMID: 19815719 DOI: 10.1152/japplphysiol.00711.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The venoarteriolar response (VAR) increases vascular resistance upon increases in venous transmural pressure in cutaneous, subcutaneous, and muscle vascular beds. During orthostasis, it has been proposed that up to 45% of the increase in systemic vascular tone is due to VAR-related local mechanism(s). The objective of this project was to test the hypothesis that heat stress attenuates VAR-mediated cutaneous and whole leg vasoconstriction. During normothermic conditions, measurements of cutaneous blood flow (laser-Doppler flowmetry) and femoral artery blood flow (Doppler ultrasound) were obtained from both legs during supine and leg-dependent conditions. These measurements were repeated following a whole body heat stress (increase in internal temperature of 1.4 +/- 0.2 degrees C). Before leg dependency, cutaneous (CVC) and femoral vascular conductances (FVC) were significantly elevated in both legs during heat stress relative to normothermia (P < 0.001). During leg dependency the absolute decrease in CVC was attenuated during heat stress (P < 0.01) while the absolute decrease in FVC was unaffected (P = 0.90). When CVC and FVC data were analyzed as a relative change from their respective baseline values, heat stress significantly attenuated the magnitude of vasoconstriction due to leg dependency in the cutaneous and femoral circulations (P < 0.001 for both variables). These data suggest that an attenuated local vasoconstriction, evoked via the venoarteriolar response, may contribute to reduced blood pressure control and thus reduced orthostatic tolerance that occurs in heat-stressed individuals.
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Affiliation(s)
- R Matthew Brothers
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas; and 2University of Texas Southwestern Medical Center at Dallas, Texas 75231, USA
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Kooijman M, Rongen GA, Smits P, van Kuppevelt HJM, Hopman MTE. The role of the alpha-adrenergic receptor in the leg vasoconstrictor response to orthostatic stress. Acta Physiol (Oxf) 2009; 195:357-66. [PMID: 18801054 DOI: 10.1111/j.1748-1716.2008.01904.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM The prompt increase in peripheral vascular resistance, mediated by sympathetic alpha-adrenergic stimulation, is believed to be the key event in blood pressure control during postural stress. However, despite the absence of central sympathetic control of the leg vasculature, postural leg vasoconstriction is preserved in spinal cord-injured individuals (SCI). This study aimed at assessing the contribution of both central and local sympathetically induced alpha-adrenergic leg vasoconstriction to head-up tilt (HUT) by including healthy individuals and SCI, who lack central sympathetic baroreflex control over the leg vascular bed. METHODS In 10 controls and nine SCI the femoral artery was cannulated for drug infusion. Upper leg blood flow (LBF) was measured bilaterally using venous occlusion strain gauge plethysmography before and during 30 degrees HUT throughout intra-arterial infusion of saline or the non-selective alpha-adrenergic receptor antagonist phentolamine respectively. Additionally, in six controls the leg vascular response to the cold pressor test was assessed during continued infusion of phentolamine, in order to confirm complete alpha-adrenergic blockade by phentolamine. RESULTS During infusion of phentolamine HUT still caused vasoconstriction in both groups: leg vascular resistance (mean arterial pressure/LBF) increased by 10 +/- 2 AU (compared with 12 +/- 2 AU during saline infusion), and 13 +/- 3 AU (compared with 7 +/- 3 AU during saline infusion) in controls and SCI respectively. CONCLUSION Effective alpha-adrenergic blockade did not reduce HUT-induced vasoconstriction, regardless of intact baroreflex control of the leg vasculature. Apparently, redundant mechanisms compensate for the absence of sympathetic alpha-adrenoceptor leg vasoconstriction in response to postural stress.
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Affiliation(s)
- M Kooijman
- Department of Physiology and Institute of Fundamental and Clinical Movement Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein Noord 21, Nijmegen, The Netherlands
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Thijssen DHJ, Green DJ, Steendijk S, Hopman MTE. Sympathetic vasomotor control does not explain the change in femoral artery shear rate pattern during arm-crank exercise. Am J Physiol Heart Circ Physiol 2009; 296:H180-5. [DOI: 10.1152/ajpheart.00686.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During lower limb exercise, blood flow through the resting upper limbs exhibits a change characterized by increased anterograde flow during systole, but also large increases in retrograde diastolic flow. One explanation for the retrograde flow is that increased sympathetic nervous system (SNS) tone and concomitant increased peripheral resistance generate a rebound during diastole. To examine whether the SNS contributes to retrograde flow patterns, we measured femoral artery blood flow during arm-crank exercise in 10 healthy men (31 ± 4 yr) and 10 spinal cord-injured (SCI) subjects who lack sympathetic innervation in the legs (33 ± 5 yr). Before, and every 5 min during 25-min arm-crank exercise at 50% maximal capacity, femoral artery blood flow and peak anterograde and retrograde shear rate were assessed using echo Doppler sonography. Femoral artery baseline blood flow was significantly lower in SCI compared with controls. Exercise increased femoral artery blood flow in both groups (ANOVA, P < 0.05), whereas leg vascular conductance did not change during exercise in either group. Mean shear rate was lower in SCI than in controls ( P < 0.05). Peak anterograde shear rate was higher in SCI than in controls ( P < 0.05), whereas peak retrograde shear rate did not differ between groups. Arm-crank exercise induced an increase in peak anterograde and retrograde shear rate in the femoral artery in controls and SCI subjects ( P < 0.05). This suggests that the SNS is not obligatory to change the flow pattern in inactive regions during exercise. Local mechanisms may play a role in the arm-crank exercise-induced changes in flow pattern in the femoral artery.
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Groothuis JT, Poelkens F, Wouters CW, Kooijman M, Hopman MTE. Leg intravenous pressure during head-up tilt. J Appl Physiol (1985) 2008; 105:811-5. [PMID: 18635882 DOI: 10.1152/japplphysiol.90304.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Leg vascular resistance is calculated as the arterial-venous pressure gradient divided by blood flow. During orthostatic challenges it is assumed that the hydrostatic pressure contributes equally to leg arterial, as well as to leg venous pressure. Because of venous valves, one may question whether, during orthostatic challenges, a continuous hydrostatic column is formed and if leg venous pressure is equal to the hydrostatic pressure. The purpose of this study was, therefore, to measure intravenous pressure in the great saphenous vein of 12 healthy individuals during 30 degrees and 70 degrees head-up tilt and compare this with the calculated hydrostatic pressure. The height difference between the heart and the right medial malleolus level represented the hydrostatic column. The results demonstrate that there were no differences between the measured intravenous pressure and the calculated hydrostatic pressure during 30 degrees (47.2 +/- 1.0 and 46.9 +/- 1.5 mmHg, respectively) and 70 degrees head-up tilt (83.9 +/- 0.9 and 85.1 +/- 1.2 mmHg, respectively). Steady-state levels of intravenous pressure were reached after 95 +/- 12 s during 30 degrees and 161 +/- 15 s during 70 degrees head-up tilt. In conclusion, the measured leg venous pressure is similar to the calculated hydrostatic pressure during orthostatic challenges. Therefore, the assumption that hydrostatic pressure contributes equally to leg arterial as well as to leg venous pressure during orthostatic challenges can be made.
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Affiliation(s)
- Jan T Groothuis
- Radboud Univ. Nijmegen Medical Centre, Dept. of Physiology, Geert Grooteplein-noord 21, 6525 EZ Nijmegen, The Netherlands
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Kooijman M, de Hoog M, Rongen GA, van Kuppevelt HJM, Smits P, Hopman MTE. Local vasoconstriction in spinal cord-injured and able-bodied individuals. J Appl Physiol (1985) 2007; 103:1070-7. [PMID: 17626837 DOI: 10.1152/japplphysiol.00053.2007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Local vasoconstriction plays an important role in maintaining blood pressure in spinal cord-injured individuals (SCI). We aimed to unravel the mechanisms of local vasoconstriction [venoarteriolar reflex (VAR) and myogenic response] using both limb dependency and cuff inflation in SCI and compare these with control subjects. Limb blood flow was measured in 11 male SCI (age: 24–55 yr old) and 9 male controls (age: 23–56 yr old) using venous occlusion plethysmography in forearm and calf during three levels of 1) limb dependency, and 2) cuff inflation. During limb dependency, vasoconstriction relies on both the VAR and the myogenic response. During cuff inflation, the decrease in blood flow is caused by the VAR and by a decrease in arteriovenous pressure difference, whereas the myogenic response does not play a role. At the highest level of leg dependency, the percent increase in calf vascular resistance (mean arterial pressure/calf blood flow) was more pronounced in SCI than in controls (SCI 186 ± 53%; controls 51 ± 17%; P = 0.032). In contrast, during cuff inflation, no differences were found between SCI and controls (SCI 17 ± 17%; controls 14 ± 10%). Percent changes in forearm vascular resistance in response to either forearm dependency or forearm cuff inflation were equal in both groups. Thus local vasoconstriction during dependency of the paralyzed leg in SCI is enhanced. The contribution of the VAR to local vasoconstriction does not differ between the groups, since no differences between groups existed for cuff inflation. Therefore, the augmented local vasoconstriction in SCI during leg dependency relies, most likely, on the myogenic response.
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Affiliation(s)
- M Kooijman
- Department of Physiology, Radboud University Nijmegen Medical Centre, Geert Grooteplein Noord 21, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Groothuis JT, van Dijk N, Ter Woerds W, Wieling W, Hopman MTE. Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances leg blood flow. Clin Sci (Lond) 2007; 112:193-201. [PMID: 16987103 DOI: 10.1042/cs20060241] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In patients with orthostatic intolerance, the mechanisms to maintain BP (blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore the purpose of the present study was to examine the peripheral haemodynamic effects of leg crossing combined with muscle tensing during 70° head-up tilt. Healthy subjects (n=13) were monitored for 10 min in the supine position followed by 10 min in 70° head-up tilt and, finally, for 2 min of leg crossing with muscle tensing in 70° head-up tilt. MAP (mean arterial BP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg blood flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as leg blood flow/MAP. A significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (−5 beats/min) and no change in total peripheral resistance during the physical counter-manoeuvre were observed when compared with baseline 70° head-up tilt. A significant increase in leg blood flow (325 ml/min) and leg vascular conductance (2.9 arbitrary units) were seen during the physical counter-manoeuvre when compared with baseline 70° head-up tilt. In conclusion, the present study indicates that the physical counter-manoeuvre of leg crossing combined with muscle tensing clearly enhances leg blood flow and, at the same time, elevates MAP.
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Affiliation(s)
- Jan T Groothuis
- Department of Physiology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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