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Sukhoplyasova M, Hamner JW, Draghici AE. The role of sympathetic control in bone vasculature: insights from spinal cord injury. J Bone Miner Res 2025; 40:404-412. [PMID: 39714231 PMCID: PMC11909726 DOI: 10.1093/jbmr/zjae204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Revised: 12/09/2024] [Accepted: 12/20/2024] [Indexed: 12/24/2024]
Abstract
Bone vasculature is richly innervated by an extensive network of sympathetic nerves. However, our understanding of bone blood flow regulation and its contribution to human bone health is limited. Here, we further our previous findings by characterizing bone vascular responses in the absence of sympathetic control-studying individuals with spinal cord injury (SCI), a population with known peripheral sympathetic disruption. We assessed tibial vascular responses to isometric handgrip exercise (IHE) in individuals with SCI (n = 12) and controls (n = 12). When sustained to fatigue, IHE increases perfusion pressure and sympathetic vasoconstriction in the nonactive tissues of the legs. During IHE, we measured blood pressure, whole leg blood velocity (LBV) via ultrasound, and tibial perfusion (as hemoglobin content) via near-infrared spectroscopy. Controls demonstrated active sympathetic vasoconstriction in the whole leg (ie, increased vascular resistance [VR], arterial pressure/LBV) and tibia (ie, decreased hemoglobin). In contrast, SCI individuals demonstrated modest whole leg vasoconstriction with lesser increases in VR than controls (p < .04). Tibial vasculature evidenced absent or blunted vasoconstriction compared to controls (p < .01), indicated by increasing tibial hemoglobin until plateauing at higher pressure levels. This suggests that, in the absence of sympathetic control, tibial vascular response may involve other regulatory mechanisms like myogenic vasoconstriction. Lastly, we leveraged existent whole-body DXA scans in a subgroup of 9 individuals with SCI, and we found a strong relationship between leg BMD and tibial hemoglobin at the end of IHE (r2 = 0.67, p < .01). Our findings indicate that in the absence of sympathetic mechanisms, myogenic control may play a compensatory role in regulating blood flow, though to a lesser extent in bone compared to muscle. The close relationship between lesser declines in bone blood content and higher BMD underscores the link between blood flow and bone health.
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Affiliation(s)
- Maria Sukhoplyasova
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA 02138, United States
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, United States
| | - Jason W Hamner
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA 02138, United States
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, United States
| | - Adina E Draghici
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA 02138, United States
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, United States
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02115, United States
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2
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Weijs RWJ, Oudegeest-Sander MH, Hopman MTE, Thijssen DHJ, Claassen JAHR. Cerebrovascular CO 2 reactivity and dynamic cerebral autoregulation through the eighth decade of life and their implications for cognitive decline. J Cereb Blood Flow Metab 2024; 44:712-725. [PMID: 38064286 PMCID: PMC11197147 DOI: 10.1177/0271678x231219568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 11/09/2023] [Accepted: 11/16/2023] [Indexed: 04/26/2024]
Abstract
Aging is accompanied by a decrease in cerebral blood flow (CBF), especially in the presence of preclinical cognitive decline. The role of cerebrovascular physiology including regulatory mechanisms of CBF in processes underlying aging and subclinical cognitive decline is, however, not fully understood. We explored changes in cerebrovascular CO2 reactivity and dynamic cerebral autoregulation (dCA) through the eighth decade of life, and their relation with early cognitive decline. After 10.9 years, twenty-eight (age, 80.0 ± 3.5 years; 46% female) out of forty-eight healthy older adults who had participated in a previous study (age at baseline, 70 ± 4 years; 42% female), underwent repeated transcranial Doppler assessments. Linear mixed-model analyses revealed small reductions in cerebrovascular CO2 reactivity with aging (-0.37%/mmHg, P = 0.041), whereas dCA was modestly enhanced (gain: -0.009 cm/s/mmHg, P = 0.038; phase: +8.9 degrees, P = 0.004). These changes were more pronounced in participants who had developed subjective memory complaints at follow-up. Our observations confirm that dCA is not impaired in aging, despite lower cerebral perfusion and cerebrovascular reactivity. Altogether, this unique longitudinal study highlights the involvement of cerebrovascular health in preclinical cognitive decline, which is of clinical relevance in the development of dementia management strategies.
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Affiliation(s)
- Ralf WJ Weijs
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Madelijn H Oudegeest-Sander
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Geriatric Medicine, Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maria TE Hopman
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dick HJ Thijssen
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Jurgen AHR Claassen
- Department of Geriatric Medicine, Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
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3
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The acute effect of dopamine infusion on lipid and cytokine concentrations in persons with a cervical spinal cord injury-a pilot study. Spinal Cord 2021; 59:274-281. [PMID: 33564118 DOI: 10.1038/s41393-021-00613-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 01/01/2021] [Accepted: 01/06/2021] [Indexed: 11/08/2022]
Abstract
STUDY DESIGN Acute experimental study. OBJECTIVES To investigate the acute response of markers of lipid metabolism and interleukin (IL)-6 to dopamine infusion in people with a cervical spinal cord injury (CSCI). SETTING Laboratory of Wakayama Medical University, Japan. METHODS Ten participants, four with CSCI and six AB individuals, underwent 50 min of dopamine infusion. Blood samples were collected prior to, immediately after and 1 h following cessation of dopamine infusion for the determination of circulating catecholamine, lipid, ketone body and IL-6 concentrations. RESULTS The adrenaline concentration following dopamine infusion was increased by 59 ± 7% in CSCI (p = 0.038, Cohen's d effect size (ES): 1.47), while this was not changed in AB (p = 0.223). Triglycerides and acetoacetic acid concentration were increased in both groups, immediately after and 1 h post-infusion (triglycerides p ≤ 0.042, ES CSCI: 1.00, ES AB: 1.12; acetoacetic acid p ≤ 0.030; ES CSCI: 1.72, ES AB: 1.31). 3-Hydroxybutyric acid concentration was increased in CSCI only (48 ± 15%, p = 0.039, ES: 1.44; AB p = 0.115). Dopamine infusion did not affect plasma IL-6 concentration in either group (p ≥ 0.368). CONCLUSIONS Dopamine infusion induced a sustained increase in triglyceride and ketone body concentrations in persons with CSCI. In contrast, cytokine concentrations were not affected by dopamine infusion. These findings suggest that circulating catecholamines can stimulate metabolism in people with CSCI despite the presence of autonomic dysfunction.
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Campos R, Mónica FZ, Justo AFO, Cogo JC, Oliveira EDT, Moreno RA, Antunes E, De Nucci G. Electrical field stimulation-induced contractions on Pantherophis guttatus corpora cavernosa and aortae. PLoS One 2018; 13:e0196123. [PMID: 29672643 PMCID: PMC5908133 DOI: 10.1371/journal.pone.0196123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 04/06/2018] [Indexed: 01/30/2023] Open
Abstract
A tetrodotoxin (TTX)-resistant mechanism is responsible for the electrical field stimulation (EFS)-induced contractions and relaxations of Crotalus durissus terrificus corpora cavernosa. Here it was investigated whether this mechanism also occurs in corpora cavernosa and aortae of the non-venomous snake Pantherophis guttatus corpora cavernosa and aortae. Corpora cavernosa and aortic rings isolated from Pantherophis guttatus snake were mounted in organ bath system for isometric tension recording. EFS-induced contractions in both tissues were performed in the presence and absence of guanethidine (30 μM), phentolamine (10 μM) and tetrodotoxin (1 μM). In another set of experiments, the endothelium was removed from aortic rings and EFS-induced contractions were performed in the denuded rings. Electrical field stimulation-induced contractions were frequency-dependent in Pantherophis guttatus corpora cavernosa and aortic rings. The contractions were significantly reduced in the presence of guanethidine (30 μM) or phentolamine (10 μM). Pre-treatment with tetrodotoxin had no effect on the EFS-induced contractions of either corpora cavernosa or aortic rings. Surprisingly, the EFS-induced contractions of aortic rings denuded of endothelium were almost abolished. These results indicate that the TTX-resistant mechanism is present in EFS-induced contractions of Pantherophis guttatus corpora cavernosa and aortae. The experiments performed in the aorta indicate that the endothelium is the main source for the release of catecholamines induced by EFS.
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Affiliation(s)
- Rafael Campos
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, (UNICAMP), Campinas, Brazil
- * E-mail:
| | - Fabíola Z. Mónica
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, (UNICAMP), Campinas, Brazil
| | | | - José Carlos Cogo
- Faculty of Biomedical Engineering, Brazil University, Itaquera—São Paulo, Brazil
| | | | - Ronilson Agnaldo Moreno
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, (UNICAMP), Campinas, Brazil
| | - Edson Antunes
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, (UNICAMP), Campinas, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, (UNICAMP), Campinas, Brazil
- Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, Brazil
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El-Kotob R, Craven BC, Mathur S, Ditor DS, Oh P, Miyatani M, Verrier MC. Assessing Heart Rate Variability As a Surrogate Measure of Cardiac Autonomic Function in Chronic Traumatic Spinal Cord Injury. Top Spinal Cord Inj Rehabil 2018; 24:28-36. [PMID: 29434458 DOI: 10.1310/sci17-00002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background: Although cardiac autonomic dysfunction is a contributing factor for cardiovascular disease development in individuals with a spinal cord injury (SCI), it remains poorly understood. Heart rate variability (HRV) analysis has the potential to non-invasively assess the cardiac autonomic nervous system. The study objectives are (a) to determine if there are differences in HRV measures across neurological level of impairment (NLI) and American Spinal Cord Injury Association Impairment Scale (AIS) subgroups, and (b) to determine if there is a relationship between HRV frequency measures (low frequency [LF] and high frequency [HF]) at rest. Methods: We conducted a secondary data analysis of a primary data set from a published cross-sectional study of electrocardiogram recordings of 56 subjects (44 men and 12 women, mean age ± SD = 46.75 ± 12.44 years) with a chronic traumatic SCI (C1-T12, AIS A-D, ≥2 years post injury). HRV was analyzed using time and frequency domain measures. Results: There were no significant HRV differences across NLI and AIS subgroups. The LF and HF indices were positively correlated in the entire sample (r = 0.708, p < .0001) and among impairment subgroups. Conclusion: No differences were observed in the HRV time and frequency measures when compared across NLI and AIS subgroups. The results were considered inconclusive, since possible explanations include inadequate sample size as well as other physiological considerations. A positive correlation was found between LF and HF when assessed at rest. The relationship between LF and HF may not necessarily represent a rebalanced autonomic nervous system, but it does question the utility of solely measuring LF:HF at rest in persons with chronic SCI.
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Affiliation(s)
- Rasha El-Kotob
- University Health Network, Toronto Rehabilitation Institute, Lyndhurst Centre, Toronto, Ontario, Canada.,Graduate Department of Rehabilitation Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - B Catharine Craven
- University Health Network, Toronto Rehabilitation Institute, Lyndhurst Centre, Toronto, Ontario, Canada.,Department of Medicine, Division of Physical Medicine & Rehabilitation, University of Toronto, Toronto, Ontario, Canada
| | - Sunita Mathur
- University Health Network, Toronto Rehabilitation Institute, University Centre, Toronto, Ontario, Canada.,Department of Physical Therapy, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - David S Ditor
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Paul Oh
- University Health Network, Toronto Rehabilitation Institute, Rumsey Centre, Toronto, Ontario, Canada.,Department of Medicine, Clinical Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Masae Miyatani
- University Health Network, Toronto Rehabilitation Institute, Lyndhurst Centre, Toronto, Ontario, Canada
| | - Mary C Verrier
- University Health Network, Toronto Rehabilitation Institute, Lyndhurst Centre, Toronto, Ontario, Canada.,Department of Physical Therapy, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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6
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Cold pressor test in spinal cord injury—revisited. Spinal Cord 2017; 56:528-537. [DOI: 10.1038/s41393-017-0037-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 11/08/2017] [Accepted: 11/11/2017] [Indexed: 11/08/2022]
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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: 0.8] [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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Tørhaug T, Brurok B, Hoff J, Helgerud J, Leivseth G. Arm Cycling Combined with Passive Leg Cycling Enhances VO 2peak in Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra. Top Spinal Cord Inj Rehabil 2017; 24:86-95. [PMID: 29434464 PMCID: PMC5791928 DOI: 10.1310/sci17-00029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Objective: To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO2peak) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results: In the SCI-high group, mean (SD) VO2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg-1·min-1; p = .002], while VO2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg-1·min-1; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion: Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.
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Affiliation(s)
- Tom Tørhaug
- St. Olavs University Hospital, Clinic of Physical Medicine and Rehabilitation, Department of Spinal Cord Injuries, Trondheim, Norway
- Norwegian University of Science and Technology, Faculty of Medicine, Department of Neuromedicine and Movement Science, Trondheim, Norway
| | - Berit Brurok
- St. Olavs University Hospital, Clinic of Physical Medicine and Rehabilitation, Department of Spinal Cord Injuries, Trondheim, Norway
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging Norwegian University of Science and Technology, Trondheim, Norway
| | - Jan Hoff
- St. Olavs University Hospital, Clinic of Physical Medicine and Rehabilitation, Department of Spinal Cord Injuries, Trondheim, Norway
- Norwegian University of Science and Technology, Faculty of Medicine, Department of Circulation and Imaging, Trondheim, Norway
| | - Jan Helgerud
- Norwegian University of Science and Technology, Faculty of Medicine, Department of Circulation and Imaging, Trondheim, Norway
- Hokksund Medical Rehabilitation Centre, Hokksund, Norway
- Telemark University College, Department of Sports and Outdoor Life Studies, Bø, Norway
| | - Gunnar Leivseth
- Norwegian University of Science and Technology, Faculty of Medicine, Department of Neuromedicine and Movement Science, Trondheim, Norway
- Department of Clinical Medicine, Neuromuscular Diseases Research Group, University of Tromsø, Norway
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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: 10] [Impact Index Per Article: 1.3] [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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10
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Accelerated Arterial Stiffening Change in Early Years of Spinal Cord Injury. Am J Phys Med Rehabil 2017; 96:120-123. [DOI: 10.1097/phm.0000000000000565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Oudegeest-Sander MH, Olde Rikkert MGM, Smits P, Thijssen DHJ, van Dijk APJ, Levine BD, Hopman MTE. The effect of an advanced glycation end-product crosslink breaker and exercise training on vascular function in older individuals: a randomized factorial design trial. Exp Gerontol 2014; 48:1509-17. [PMID: 24400341 DOI: 10.1016/j.exger.2013.10.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Aging leads to accumulation of irreversible advanced glycation end-products (AGEs), contributing to vascular stiffening and endothelial dysfunction. When combined with the AGE-crosslink breaker Alagebrium, exercise training reverses cardiovascular aging in experimental animals. This study is the first to examine the effect of Alagebrium, with and without exercise training, on endothelial function, arterial stiffness and cardiovascular risk in older individuals. Forty-eight non-exercising individuals (mean age 70 ± 4 years) without manifest diseases or use of medication were allocated into 4 groups for a 1-year intervention: Exercise training & Alagebrium (200 mg/day); exercise training & placebo; no exercise training & Alagebrium (200 mg/day); and no exercise training & placebo. We performed a maximal exercise test (VO2max) and measured endothelial function using venous occlusion plethysmography and intra-arterial infusion of acetylcholine, sodium nitroprusside and NG-monomethyl-l-arginine. Arterial stiffness was measured using pulse wave velocity. Cardiovascular risk was calculated using the Lifetime Risk Score (LRS). In the exercise training groups, LRS and VO2max improved significantly (23.9 ± 4.5 to 27.2 ± 4.6mLO2/min/kg, p < 0.001). Endothelial response to the vasoactive substances did not change, nor did arterial stiffness in any of the four groups. In conclusion, one year of exercise training significantly improved physical fitness and lifetime risk for cardiovascular disease without affecting endothelial function or arterial stiffness. The use of the AGE-crosslink breaker Alagebrium had no independent effect on vascular function, nor did it potentiate the effect of exercise training. Despite the clinical benefits of exercise training for older individuals, neither exercise training nor Alagebrium (alone or in combination) was able to reverse the vascular effects of decades of sedentary aging.
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Tzen YT, Brienza DM, Karg PE, Loughlin PJ. Effectiveness of local cooling for enhancing tissue ischemia tolerance in people with spinal cord injury. J Spinal Cord Med 2013; 36:357-64. [PMID: 23820151 PMCID: PMC3758532 DOI: 10.1179/2045772312y.0000000085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVE To investigate the effects of localized cooling and cooling rate on pressure-induced ischemia for people with and without neurological deficits. DESIGN A 2 × 3 mixed factorial design with two groups: (1) people with spinal cord injury (SCI) and (2) people without neurological deficits (control), and three test conditions: (1) pressure only, (2) pressure with fast cooling (-4°C/min), and (3) pressure with slow cooling (-0.33°C/min). SETTING University laboratory. PARTICIPANTS Fourteen controls and 14 individuals with SCI. INTERVENTIONS Pressure on the sacrum was 0.4 kPa for 5 minutes, then 8 kPa for 20 minutes, and finally 0.4 kPa for 15 minutes. Fast and slow cooling to 25°C applied during 8 kPa of pressure. OUTCOME MEASURES Reactive hyperemia and its spectral densities in the metabolic, neurogenic, and myogenic frequency ranges. RESULTS In controls, reactive hyperemia was greater in pressure only as compared with both cooling conditions. No change was noted in all spectral densities in both cooling conditions, and only neurogenic spectral density increased without cooling. In subjects with SCI, no difference was noted in reactive hyperemia among conditions. However, metabolic and myogenic spectral densities increased without cooling and all spectral densities increased with slow cooling. No change was noted in all spectral densities with fast cooling. CONCLUSION Local cooling reduced the severity of ischemia in controls. This protective effect may be masked in subjects with SCI due to chronic microvascular changes; however, spectral analysis suggested local cooling may reduce metabolic vasodilation. These findings provide evidence towards the development of support surfaces with temperature control for weight-bearing soft tissues.
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Affiliation(s)
- Yi-Ting Tzen
- University of Pittsburgh, Pittsburgh, PA 15206, USA.
| | - David M. Brienza
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Patricia E. Karg
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA, USA
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13
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Hybrid equation/agent-based model of ischemia-induced hyperemia and pressure ulcer formation predicts greater propensity to ulcerate in subjects with spinal cord injury. PLoS Comput Biol 2013; 9:e1003070. [PMID: 23696726 PMCID: PMC3656105 DOI: 10.1371/journal.pcbi.1003070] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/09/2013] [Indexed: 12/18/2022] Open
Abstract
Pressure ulcers are costly and life-threatening complications for people with spinal cord injury (SCI). People with SCI also exhibit differential blood flow properties in non-ulcerated skin. We hypothesized that a computer simulation of the pressure ulcer formation process, informed by data regarding skin blood flow and reactive hyperemia in response to pressure, could provide insights into the pathogenesis and effective treatment of post-SCI pressure ulcers. Agent-Based Models (ABM) are useful in settings such as pressure ulcers, in which spatial realism is important. Ordinary Differential Equation-based (ODE) models are useful when modeling physiological phenomena such as reactive hyperemia. Accordingly, we constructed a hybrid model that combines ODEs related to blood flow along with an ABM of skin injury, inflammation, and ulcer formation. The relationship between pressure and the course of ulcer formation, as well as several other important characteristic patterns of pressure ulcer formation, was demonstrated in this model. The ODE portion of this model was calibrated to data related to blood flow following experimental pressure responses in non-injured human subjects or to data from people with SCI. This model predicted a higher propensity to form ulcers in response to pressure in people with SCI vs. non-injured control subjects, and thus may serve as novel diagnostic platform for post-SCI ulcer formation.
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14
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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: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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15
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Previnaire JG, Soler JM, Leclercq V, Denys P. Severity of autonomic dysfunction in patients with complete spinal cord injury. Clin Auton Res 2011; 22:9-15. [DOI: 10.1007/s10286-011-0132-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 06/08/2011] [Indexed: 01/07/2023]
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Thijssen DHJ, Green DJ, Hopman MTE. Blood vessel remodeling and physical inactivity in humans. J Appl Physiol (1985) 2011; 111:1836-45. [PMID: 21737819 DOI: 10.1152/japplphysiol.00394.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Physical inactivity is associated with an increase in cardiovascular risk that cannot be fully explained by traditional or novel risk factors. Inactivity is also associated with changes in hemodynamic stimuli, which exert direct effects on the vasculature leading to remodeling and a proatherogenic phenotype. In this review, we synthesize and summarize in vivo evidence relating to the impact of local and systemic models of physical inactivity on conduit arteries, resistance vessels, and the microcirculation in humans. Taken together, the literature suggests that a rapid inward structural remodeling of vessels occurs in response to physical inactivity. The magnitude of this response is dependent on the "dose" of inactivity. Moreover, changes in vascular function are found at resistance and microvessel levels in humans. In conduit arteries, a strong interaction between vascular function and structure is present, which results in conflicting data regarding the impact of inactivity on conduit artery function. While much of the cardioprotective effect of exercise is related to the nitric oxide pathway, deconditioning may primarily be associated with activation of vasoconstrictor pathways. The effects of deconditioning on the vasculature are therefore not simply the opposite of those in response to exercise training. Given the importance of sedentary behavior, future studies should provide further insight into the impact of inactivity on the vasculature and other (novel) markers of vascular health. Moreover, studies should examine the role of (hemodynamic) stimuli that underlie the characteristic vascular adaptations during deconditioning. Our review concludes with some suggestions for future research directions.
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Affiliation(s)
- Dick H J Thijssen
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom.
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Bernjak A, Deitrick G, Bauman W, Stefanovska A, Tuckman J. Basal sympathetic activity to the microcirculation in tetraplegic man revealed by wavelet transform of laser Doppler flowmetry. Microvasc Res 2011; 81:313-8. [DOI: 10.1016/j.mvr.2011.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/14/2011] [Accepted: 01/14/2011] [Indexed: 10/18/2022]
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18
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Phillips AA, Cote AT, Warburton DER. A systematic review of exercise as a therapeutic intervention to improve arterial function in persons living with spinal cord injury. Spinal Cord 2011; 49:702-14. [DOI: 10.1038/sc.2010.193] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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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: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Prévinaire JG, Mathias CJ, El Masri W, Soler JM, Leclercq V, Denys P. The isolated sympathetic spinal cord: Cardiovascular and sudomotor assessment in spinal cord injury patients: A literature survey. Ann Phys Rehabil Med 2010; 53:520-32. [PMID: 20797928 DOI: 10.1016/j.rehab.2010.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 06/21/2010] [Accepted: 06/29/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVES To present a comprehensive approach to the assessment of the severity of the autonomic lesion in spinal cord injury (SCI) patients, with regard to the level of lesion. To discuss how to assess an isolated sympathetic spinal cord that has lost supraspinal control (sympathetically complete lesion). METHOD PubMed was searched for articles related to cardiovascular (mainly cold pressor test, respiratory and postural challenges) and sudomotor (sympathetic skin responses) tests that have been used. The results of these evaluations are analysed with regard to the site of stimulation (above or below the lesion) according to three types of SCI that offer typical autonomic reactions (tetraplegics, paraplegics at T6 and at T10). RESULTS Non-invasive cardiovascular and sudomotor testing allows the assessment of the isolated sympathetic spinal cord in SCI patients. Typical responses are found in relation with the level of the sympathetic lesion. Its definition would allow comparison with the somatic motor and sensory level of lesion of SCI patients and provide additional aid to the classification of those patients. CONCLUSION For research purposes on the integrity of the spinal sympathetic pathways, a battery of test approach is probably needed, using a combination of stimuli above and below the lesion, evaluating both cardiovascular and sudomotor pathways.
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Affiliation(s)
- J G Prévinaire
- Département médullaire, centre Calvé, fondation Hopale, 62600 Berck-sur-Mer, France.
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Groothuis JT, Rongen GA, Deinum J, Pickkers P, Danser AHJ, Geurts AC, Smits P, Hopman MT. Sympathetic Nonadrenergic Transmission Contributes to Autonomic Dysreflexia in Spinal Cord–Injured Individuals. Hypertension 2010; 55:636-43. [DOI: 10.1161/hypertensionaha.109.147330] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Autonomic dysreflexia is a hypertensive episode in spinal cord–injured individuals induced by exaggerated sympathetic activity and thought to be α-adrenergic mediated. α-Adrenoceptor antagonists have been a rational first choice; nevertheless, calcium channel blockers are primarily used in autonomic dysreflexia management. However, α-adrenoceptor blockade may leave a residual vasoconstrictor response to sympathetic nonadrenergic transmission unaffected. The aim was to assess the α-adrenergic contribution and, in addition, the role of supraspinal control to leg vasoconstriction during exaggerated sympathetic activity provoked by autonomic dysreflexia in spinal cord–injured individuals and by a cold pressure test in control individuals. Upper leg blood flow was measured using venous occlusion plethysmography during supine rest and during exaggerated sympathetic activity in 6 spinal cord–injured individuals and 7 able-bodied control individuals, without and with phentolamine (α-adrenoceptor antagonist) and nicardipine (calcium channel blocker) infusion into the right femoral artery. Leg vascular resistance was calculated. In spinal cord–injured individuals, phentolamine significantly reduced the leg vascular resistance increase during autonomic dysreflexia (8±5 versus 24±13 arbitrary units;
P
=0.04) in contrast to nicardipine (15±10 versus 24±13 arbitrary units;
P
=0.12). In controls, phentolamine completely abolished the leg vascular resistance increase during a cold pressure test (1±2 versus 18±14 arbitrary units;
P
=0.02). The norepinephrine increase during phentolamine infusion was larger (
P
=0.04) in control than in spinal cord–injured individuals. These results indicate that the leg vascular resistance increase during autonomic dysreflexia in spinal cord–injured individuals is not entirely α-adrenergic mediated and is partly explained by nonadrenergic transmission, which may, in healthy subjects, be suppressed by supraspinal control.
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Affiliation(s)
- Jan T. Groothuis
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Gerard A. Rongen
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Jaap Deinum
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Peter Pickkers
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - A. H. Jan Danser
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Alexander C.H. Geurts
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Paul Smits
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Maria T.E. Hopman
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
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22
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Thijssen DHJ, Maiorana AJ, O’Driscoll G, Cable NT, Hopman MTE, Green DJ. Impact of inactivity and exercise on the vasculature in humans. Eur J Appl Physiol 2010; 108:845-75. [PMID: 19943061 PMCID: PMC2829129 DOI: 10.1007/s00421-009-1260-x] [Citation(s) in RCA: 198] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2009] [Indexed: 12/12/2022]
Abstract
The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.
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Affiliation(s)
- Dick H. J. Thijssen
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, 15–21 Webster Street, Liverpool, L3 2ET UK
- Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Andrew J. Maiorana
- Advanced Heart Failure and Cardiac Transplant Service, Royal Perth Hospital, Perth, Australia
- School of Physiotherapy, Curtin University of Technology, Perth, Australia
| | - Gerry O’Driscoll
- Advanced Heart Failure and Cardiac Transplant Service, Royal Perth Hospital, Perth, Australia
- School of Medicine, University of Notre Dame, Fremantle, Australia
| | - Nigel T. Cable
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, 15–21 Webster Street, Liverpool, L3 2ET UK
| | - Maria T. E. Hopman
- Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Daniel J. Green
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, 15–21 Webster Street, Liverpool, L3 2ET UK
- School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia
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23
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La Fountaine MF, Radulovic M, Cardozo CP, Spungen AM, DeMeersman RE, Bauman WA. Effects of acute nitric oxide synthase inhibition on lower leg vascular function in chronic tetraplegia. J Spinal Cord Med 2009; 32:538-44. [PMID: 20025149 PMCID: PMC2792459 DOI: 10.1080/10790268.2009.11754555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND/OBJECTIVE To improve our understanding of the lower-leg vascular responses of nitric oxide synthase inhibition in persons with tetraplegia. PARTICIPANTS Six people with chronic tetraplegia and 6 age-matched controls. METHODS Lower-leg relative vascular resistance and venous volume variation were obtained by venous occlusion plethysmography and blood pressure by auscultation at baseline. Postintravenous infusion of the nitric oxide synthase inhibitor NG-nitro-L-arginine-methyl-ester (1 mg x kg(-1) or placebo on separate days. RESULTS At baseline in the group with tetraplegia compared with controls, mean arterial pressure and relative vascular resistance of the leg were significantly lower. After nitric oxide synthase inhibition, mean arterial pressure and lower leg vascular resistance were significantly elevated in both groups. There were no group or intervention differences in venous volume variation. CONCLUSION These preliminary results suggest that nitric oxide synthase inhibition with 1 mg x kg(-1) N(G)-nitro-L-arginine-methyl-ester normalizes seated blood pressure and lower leg vascular resistance to control group baseline levels.
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Affiliation(s)
- Michael F La Fountaine
- VA Center of Excellence on the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, SCI Room 1E-02, 130 W. Kingsbridge Road, Bronx, NY 10468, USA.
| | - Miroslav Radulovic
- VA Center of Excellence on the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, Bronx, New York
| | - Christopher P Cardozo
- VA Center of Excellence on the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, Bronx, New York
| | - Ann M Spungen
- VA Center of Excellence on the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, Bronx, New York
| | - Ronald E DeMeersman
- Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, New York
| | - William A Bauman
- VA Center of Excellence on the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, Bronx, New York
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24
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25
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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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26
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Ballaz L, Fusco N, Crétual A, Langella B, Brissot R. Peripheral Vascular Changes After Home-Based Passive Leg Cycle Exercise Training in People With Paraplegia: A Pilot Study. Arch Phys Med Rehabil 2008; 89:2162-6. [DOI: 10.1016/j.apmr.2008.04.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/11/2008] [Accepted: 04/15/2008] [Indexed: 11/28/2022]
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27
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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: 1.1] [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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28
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The effects of functional electrical stimulation leg cycle ergometry training on arterial compliance in individuals with spinal cord injury. Spinal Cord 2008; 46:722-6. [PMID: 18414425 DOI: 10.1038/sc.2008.34] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
STUDY DESIGN A prospective intervention of functional electrical stimulation leg cycle ergometry (FES-LCE) of four women with spinal cord injury (SCI). OBJECTIVE To evaluate the effect of FES-LCE training on arterial compliance in individuals with chronic SCI of traumatic origin. SETTING Tertiary rehabilitation center in Canada. METHODS Large and small artery compliance were measured at the radial artery before and after a 3-month training program using FES-LCE. RESULTS There was no significant change in large artery compliance after FES-LCE (16.0+/-4.2 to 16.8+/-6.1 ml mm Hg(-1) x 10, P=NS). There was a marked (63%) increase in small artery compliance after the FES training program (4.2+/-1.8 to 6.9+/-3.2 ml mm Hg(-1) x 100, P<0.05). CONCLUSION It appears that FES-LCE is effective in improving small artery compliance in females with SCI.
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Wecht JM, Weir JP, Goldstein DS, Krothe-Petroff A, Spungen AM, Holmes C, Bauman WA. Direct and reflexive effects of nitric oxide synthase inhibition on blood pressure. Am J Physiol Heart Circ Physiol 2007; 294:H190-7. [PMID: 17965289 DOI: 10.1152/ajpheart.00366.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Direct effects of vasoactive substances on blood pressure can be examined in individuals with tetraplegia due to disruption of descending spinal pathways to sympathetic preganglionic neurons, as cervical lesions interfere with baroreceptor reflex buffering of sympathetic outflow. In this study, we assessed effects of the nitric oxide synthase inhibitor nitro-L-arginine methyl ester (L-NAME) on mean arterial pressure, heart rate, and plasma norepinephrine concentrations in individuals with tetraplegia vs. effects shown in a neurologically intact control group. Seven individuals with tetraplegia and seven age-matched controls received, on separate visits and in the following order, placebo (30 ml normal saline) and 0.5, 1, 2, and 4 mg/kg L-NAME intravenously over 60 min. Supine hemodynamic data were collected, and blood was sampled at the end of each infusion and at 120, 180, and 240 min thereafter. L-NAME increased mean arterial pressure, and the relative increase was greater in the tetraplegia group than in the control group. Heart rate was reduced after L-NAME administration in both groups. L-NAME decreased plasma norepinephrine in the control group but not in the group with tetraplegia. These findings suggest that reflexive sympathoinhibition normally buffers the pressor response to nitric oxide synthase inhibition, an effect that is not evident in individuals with tetraplegia as a result of decentralized sympathetic vasomotor control.
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Affiliation(s)
- Jill M Wecht
- Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, 130 West Kingsbridge Rd., Bronx, NY 10468, USA.
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30
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Thijssen DHJ, Rongen GA, van Dijk A, Smits P, Hopman MTE. Enhanced endothelin-1-mediated leg vascular tone in healthy older subjects. J Appl Physiol (1985) 2007; 103:852-7. [PMID: 17556493 DOI: 10.1152/japplphysiol.00357.2007] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
UNLABELLED Advanced age is associated with a decreased leg blood flow and reduced physical activity. Endothelin (ET-1), a powerful vasoconstrictor, may play a role in the increased leg vascular tone in older men. objectives: to assess the ET-1-mediated vascular tone in the legs of healthy sedentary older men, both before and after 8 wk of exercise training. methods: in 8 younger subjects (19-50 yr) and 8 older men (67-76 yr), bilateral leg blood flow was measured using venous occlusion plethysmography before and after antagonizing ET-1 (using selective ET(A/B)-receptor antagonists). In older men, reversibility of the observations was assessed after 8 wk of cycling. results: ET-receptor inhibition increased leg blood flow significantly more in older men compared with younger individuals (29 +/- 9% and 10 +/- 4%, respectively, P < 0.05). Eight-week cycling training increased baseline blood flow in older men. The blood flow response to ET-receptor inhibition in older men was not affected by the training program (25 +/- 8%, P > 0.05 for comparison with pretraining). The flow ratio (blood flows infused leg/noninfused leg) decreased significantly by training from 26 +/- 8% to 7+3% (P < 0.05). CONCLUSION the increased baseline vascular tone in aging is at least in part mediated by the endothelin. Eight-weeks cycling training in older sedentary men decreased leg vascular tone and seems to partly decrease the ET-1-mediated vascular tone.
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Affiliation(s)
- Dick H J Thijssen
- Department of Physiology, Radboud University Nijmegen Medical Centre, Geert Grooteplein-Noord 21, 6525 EZ, Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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31
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Thijssen DHJ, Ellenkamp R, Kooijman M, Pickkers P, Rongen GA, Hopman MTE, Smits P. A Causal Role for Endothelin-1 in the Vascular Adaptation to Skeletal Muscle Deconditioning in Spinal Cord injury. Arterioscler Thromb Vasc Biol 2007; 27:325-31. [PMID: 17122448 DOI: 10.1161/01.atv.0000253502.83167.31] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Endothelin-1 (ET-1) contributes to the increased peripheral resistance in heart failure and hypertension. Physical inactivity is associated with cardiovascular disease and characterized by increased vascular tone. In this study, we assess the contribution of ET-1 to the increased vascular tone in the extremely deconditioned legs of spinal cord-injured (SCI) individuals before and after exercise training. METHODS AND RESULTS In 8 controls and 8 SCI individuals, bilateral thigh blood flow was measured by plethysmography before and during the administration of an ET(A)/ET(B)-receptor blocker into the femoral artery. In SCI, this procedure was repeated after 6 weeks of electro-stimulated training. In a subset of SCI (n=4), selective ET(A)-receptor blockade was performed to determine the role of the ET(A)-receptors. In controls, dual ET-receptor blockade increased leg blood flow at the infused side (10%, P<0.05), indicating a small contribution of ET-1 to leg vascular tone. In SCI, baseline blood flow was lower compared with controls (P=0.05). In SCI, dual ET-receptor blockade increased blood flow (41%, P<0.001). This vasodilator response was significantly larger in SCI compared with controls (P<0.001). The response to selective ET(A)-receptor blockade was similar to the effect of dual blockade. Electro-stimulated training normalized baseline blood flow in SCI and reduced the response to dual ET-receptor blockade in the infused leg (29%, P=0.04). CONCLUSIONS ET-1 mediates the increased vascular tone of extremely inactive legs of SCI individuals by increased activation of ET(A)-receptors. Physical training reverses the ET-1-pathway, which normalizes basal leg vascular tone.
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Affiliation(s)
- Dick H J Thijssen
- Department of Physiology, Institute of Fundamental and Clinical Movement Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein-Noord 21, 6525 EZ, Nijmegen, The Netherlands
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Thijssen DHJ, de Groot P, Kooijman M, Smits P, Hopman MTE. Sympathetic nervous system contributes to the age-related impairment of flow-mediated dilation of the superficial femoral artery. Am J Physiol Heart Circ Physiol 2006; 291:H3122-9. [PMID: 16844924 DOI: 10.1152/ajpheart.00240.2006] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The physiological aging process is associated with endothelial dysfunction, as assessed by flow-mediated dilation (FMD). Aging is also characterized by increased sympathetic tone. Therefore, the aim of the present study is to assess whether acute changes in sympathetic activity alter FMD in the leg. For this purpose, the FMD of the superficial femoral artery was determined in 10 healthy young (22 +/- 1 yr) and 8 healthy older (69 +/- 1 yr) men in three different conditions: 1) at baseline, 2) during reduction of sympathetic activity, and 3) during sympathetic stimulation. Reduction of sympathetic activity was achieved by performing a maximal cycling exercise, leading to postexercise attenuation of the sympathetic responsiveness in the exercised limb. A cold pressor test was used to increase sympathetic activity. Nitroglycerin (NTG) was used to assess endothelium-independent vasodilation in all three conditions. Our results showed that, in older men, the FMD and NTG responses were significantly lower compared with young men (P = 0.001 and P = 0.02, respectively). In older men, sympathetic activity significantly affected the FMD response [repeated-measures (RM) ANOVA: P = 0.01], with a negative correlation between the level of sympathetic activity and FMD (R = -0.41, P = 0.049). This was not the case for NTG responses (ANOVA; P = 0.48). FMD and NTG responses in young men did not differ among the three conditions (RM-ANOVA: P = 0.32 and P = 0.31, respectively). In conclusion, in older men, FMD of the femoral artery is impaired. Local attenuation of the sympathetic responsiveness partly restores the FMD in these subjects. In contrast, in young subjects, acute modulation of the sympathetic nervous system activity does not alter flow-mediated vasodilation in the leg.
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Affiliation(s)
- Dick H J Thijssen
- Dept. of Physiology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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de Groot PC, Bleeker MW, van Kuppevelt DH, van der Woude LH, Hopman MT. Rapid and extensive arterial adaptations after spinal cord injury. Arch Phys Med Rehabil 2006; 87:688-96. [PMID: 16635632 DOI: 10.1016/j.apmr.2006.01.022] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 01/27/2006] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the time course of adaptations in leg vascular dimension and function within the first 6 weeks after a spinal cord injury (SCI). DESIGN Longitudinal study design. SETTING University medical center and rehabilitation clinic. PARTICIPANTS Six men were studied serially at 1, 2, 3, 4, and 6 weeks after SCI. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Diameter, blood flow, and shear rate levels of the common femoral artery (CFA), superficial femoral artery (SFA), brachial artery, and carotid artery were measured with echo Doppler ultrasound (diameter, blood flow, shear rate). Endothelial function in the SFA was measured with flow-mediated dilation (FMD). In addition, leg volume and blood pressure measurements were performed. RESULTS Femoral artery diameter (CFA, 25%; SFA, 16%; P<.01) and leg volume (22%, P<.01) decreased simultaneously, and these reductions were largely accomplished within 3 weeks postinjury. Significant increases were observed for basal shear rate levels (64% increase at week 3; 117% increase at week 6; P<.01), absolute FMD responses (8% increase at week 3, 23% increase at week 6; P<.05) and relative FMD responses (26% increase at week 3, 44% increase at week 6; P<.001). CONCLUSIONS Our findings show a rapid onset of adaptations in arterial dimension and function to extreme inactivity in humans. Vascular adaptations include extensive reductions in femoral diameter and leg volume, as well as increased basal shear rate levels and FMD responses, which all appear to be largely accomplished within 3 weeks after an SCI.
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Affiliation(s)
- Patricia C de Groot
- Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
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Clark JM, Jelbart M, Rischbieth H, Strayer J, Chatterton B, Schultz C, Marshall R. Physiological effects of lower extremity functional electrical stimulation in early spinal cord injury: lack of efficacy to prevent bone loss. Spinal Cord 2006; 45:78-85. [PMID: 16636686 DOI: 10.1038/sj.sc.3101929] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Controlled, repeat-measures study. OBJECTIVES To determine if functional electrical stimulation (FES) can affect bone atrophy in early spinal cord injury (SCI), and the safety, tolerance and feasibility of this modality in bone loss remediation. SETTING Spinal Injuries Units, Royal Adelaide Hospital and Hampstead Rehabilitation Centre, South Australia. METHODS Patients with acute SCI (ASIA A-D) were allocated to FES (n=23, 28+/-9 years, C4-T10, 13 Tetra) and control groups (CON, n=10, 31+/-11 years, C5-T12, four Tetra). The intervention group received discontinuous FES to lower limb muscles (15 min sessions to each leg twice daily, over a 5-day week, for 5 months). Dual energy X-ray absorptiometry (DEXA) measured total body bone mineral density (tbBMD), hip, spine BMD and fat mass (FM) within 3 weeks, and 3 and 6 months postinjury. RESULTS FES and CON groups' tbBMD differed significantly at 3 months postinjury (P<0.01), but not thereafter. Other DEXA measures (hip, spine BMD, FM) did not differ between groups at any time. No adverse events were identified. CONCLUSION Electrically stimulated muscle activation was elicited, and tetanic effects were reproducible; however, there were no convincing trends to suggest that FES can play a clinically relevant role in osteoporosis prevention (or subsequent fracture risk) in the recently injured patient. The lack of an osteogenic response in paralysed extremities to electrically evoked exercise during subacute and rehabilitation/recovery phases cannot be fully explained, and may warrant further evaluation.
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Affiliation(s)
- J M Clark
- Division of Orthopaedics and Trauma Service, Faculty of Health Sciences, University of Adelaide, Adelaide, SA, Australia
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de Groot P, Crozier J, Rakobowchuk M, Hopman M, MacDonald M. Electrical stimulation alters FMD and arterial compliance in extremely inactive legs. Med Sci Sports Exerc 2005; 37:1356-64. [PMID: 16118583 DOI: 10.1249/01.mss.0000174890.13395.e7] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The main aim of the study was to assess the effect and time course of 4 wk of electrically induced leg training on arterial compliance and endothelial function. METHODS Six spinal cord-injured (SCI) individuals participated in 4 wk of daily one-leg functional electrical stimulation (FES) training for 30 min per session. Eight able-bodied individuals served as a control group (C) and were tested on one occasion. Echo Doppler measurements were performed before the FES training and after 1, 2, and 4 wk of training to measure vascular characteristics of femoral artery (FA), brachial artery (BA), and carotid artery (CA). RESULTS Baseline arterial compliance of FA (SCI: 0.0185 +/- 0.063 mm2 x mm Hg(-1); C: 0.066 +/- 0.017 mm2 x mm Hg(-1), P = 0.001) and CA (SCI: 0.073 +/- 0.02 mm2 x mm Hg(-1); C: 0.102 +/- 0.02 mm2 x mm Hg(-1), P = 0.02) was significantly decreased in SCI. Baseline endothelial function in the leg was significantly enhanced in SCI compared with C (SCI: 11 +/- 1.3%; C: 7.9 +/- 0.9%, P = 0.001). No differences between the groups were found for arterial compliance and endothelial function in the arm. Vascular changes after FES training showed an increase in arterial compliance (significant at week 4, P < 0.05) and a decrease in FMD response (significant at weeks 2 and 4, P < 0.05) in the FA of the trained leg only, with no changes evident in the other arteries examined. CONCLUSION Daily electrically induced training of an extremely deconditioned leg appears to enhance arterial compliance in the femoral artery and may normalize endothelial function.
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Affiliation(s)
- Patricia de Groot
- Department of Physiology, University Medical Center Nijmegen, the Netherlands
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Groothuis JT, Boot CRL, Houtman S, van Langen H, Hopman MTE. Leg vascular resistance increases during head-up tilt in paraplegics. Eur J Appl Physiol 2005; 94:408-14. [PMID: 15843958 DOI: 10.1007/s00421-005-1340-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2005] [Indexed: 10/25/2022]
Abstract
Despite loss of centrally mediated sympathetic vasoconstriction to the legs, spinal cord-injured individuals cope surprisingly well with an orthostatic challenge. This study assessed changes in leg vascular resistance following head-up tilt in healthy (C) and in paraplegic (P) individuals. After 10 min of supine rest, subjects were tilted 30 degrees head-up. Mean arterial pressure (MAP) and total peripheral resistance (TPR) increased in C (MAP from 76.7 +/ -6.6 mmHg to 80.6 +/- 8.2 mmHg; TPR from 1.12 +/- 0.26 AU to 1.19 +/ -0.31 AU) while both remained unchanged in P. Echo Doppler ultrasound determined red blood cell velocity in the femoral artery, which decreased (P from 18.9+/-6.2 cm/s to 12.5 +/- 4.5 cm/s, P = 0.001; C from 16.3 +/- 6.2 cm/s to 10.8 +/- 5.0 cm/s, P = 0.001) and leg vascular resistance, which increased (P from 402 +/- 137 AU to 643 +/- 274 AU, P = 0.001; C from 238 +/- 68 AU to 400 +/- 122 AU, P = 0.003) from supine to upright. The present study shows that independent of supraspinal sympathetic control, humans are able to increase leg vascular resistance and maintain blood pressure during head-up tilt.
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Affiliation(s)
- Jan T Groothuis
- Department of Physiology, University Medical Centre Nijmegen, The Netherlands
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Groothuis JT, Boot CRL, Houtman S, van Langen H, Hopman MTE. Does peripheral nerve degeneration affect circulatory responses to head-up tilt in spinal cord-injured individuals? Clin Auton Res 2005; 15:99-106. [DOI: 10.1007/s10286-005-0248-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Accepted: 11/15/2004] [Indexed: 10/25/2022]
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Bleeker MWP, Kooijman M, Rongen GA, Hopman MTE, Smits P. Preserved contribution of nitric oxide to baseline vascular tone in deconditioned human skeletal muscle. J Physiol 2005; 565:685-94. [PMID: 15802292 PMCID: PMC1464521 DOI: 10.1113/jphysiol.2005.085936] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Deconditioning is a risk factor for cardiovascular disease. Exercise reduces this risk, possibly by improving the vascular endothelial nitric oxide (NO) pathway. The effect of deconditioning on the NO pathway is largely unknown. This study was designed to assess baseline NO availability in the leg vascular bed after extreme, long-term deconditioning (spinal cord-injured individuals, SCI) as well as after moderate, short-term deconditioning (4 weeks of unilateral lower limb suspension, ULLS). For this purpose, seven SCI were compared with seven matched controls. Additionally, seven healthy subjects were studied pre- and post-ULLS. Leg blood flow was measured by venous occlusion plethysmography at baseline and during infusion of 5 incremental dosages of N(G)-monomethyl-L-arginine (L-NMMA) into the femoral artery. Sodium nitroprusside (SNP) was infused to test vascular responsiveness to NO. Baseline leg vascular resistance tended to be higher in SCI compared with controls (37+/-4 versus 31+/-2 arbitrary units (AU), P=0.06). Deconditioning altered neither the vasoconstrictor response to L-NMMA (increase in resistance in SCI versus controls: 102+/-33% versus 69+/-9%; pre- versus post-ULLS: 95+/-18% versus 119+/-15%), nor the vascular responsiveness to NO. In conclusion, two human in vivo models of deconditioning show a preserved baseline NO availability in the leg skeletal muscle vascular bed.
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Affiliation(s)
- Michiel W P Bleeker
- Department of Pharmacology-Toxicology 233, Radboud University Nijmegen Medical Centre, Geert Grooteplein Noord 21, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Thijssen DHJ, Bleeker MWP, Smits P, Hopman MTE. Reproducibility of blood flow and post-occlusive reactive hyperaemia as measured by venous occlusion plethysmography. Clin Sci (Lond) 2005; 108:151-7. [PMID: 15494042 DOI: 10.1042/cs20040177] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Venous occlusion plethysmography is commonly used as a tool to assess BF (blood flow) and VR (vascular resistance) at baseline and during PORH (post-occlusive reactive hyperaemia). However, little is known about the reproducibility of this method. The purpose of the present study was to investigate short- (hours) and medium (week)-term reproducibility of forearm, calf and thigh BF and VR at baseline and during PORH. Reproducibility was assessed by the CV (coefficient of variation). In eight subjects, baseline BF and VR of the forearm, calf and thigh were measured using venous occlusion plethysmography (50 mmHg). PORH and minimal VR were measured after 13 min of arterial occlusion (220 mmHg). Reproducibility of baseline forearm and calf BF was acceptable and in agreement with previous studies (CV, 12.9–21.2%). Short- and medium-term reproducibility of thigh BF was good (CV, 5.9% and 8.7% respectively). Baseline VR showed acceptable-to-good reproducibility for forearm, calf and thigh (8.3–22.5%). Forearm PORH showed a CV of 6.1% (short term) and 8.6% (medium term); this was 6.1% (short term) and 6.4% (medium term) for the calf and 6.4% (short term) and 8.0% (medium term) for the thigh. Minimal VR showed good-to-acceptable reproducibility (CV, 6.1–11.7%). In conclusion, forearm, calf and thigh BF and PORH measured by plethysmography have an acceptable-to-good short- and medium-term reproducibility. Short- and medium-term reproducibility of forearm and calf baseline BF are acceptable and thigh baseline BF has a good short- and medium-term reproducibility. Therefore plethysmography is a suitable low-cost tool to assess thigh baseline BF and PORH.
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Affiliation(s)
- Dick H J Thijssen
- Department of Physiology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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