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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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Habazettl H, Stahn A, Nitsche A, Nordine M, Pries AR, Gunga HC, Opatz O. Microvascular responses to (hyper-)gravitational stress by short-arm human centrifuge: arteriolar vasoconstriction and venous pooling. Eur J Appl Physiol 2015; 116:57-65. [PMID: 26280651 DOI: 10.1007/s00421-015-3241-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 08/08/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE We hypothesized that lower body microvessels are particularly challenged during exposure to gravity and hypergravity leading to failure of resistance vessels to withstand excessive transmural pressure during hypergravitation and gravitation-dependent microvascular blood pooling. METHODS Using a short-arm human centrifuge (SAHC), 12 subjects were exposed to +1Gz, +2Gz and +1Gz, all at foot level, for 4 min each. Laser Doppler imaging and near-infrared spectroscopy were used to measure skin perfusion and tissue haemoglobin concentrations, respectively. RESULTS Pretibial skin perfusion decreased by 19% during +1Gz and remained at this level during +2Gz. In the dilated area, skin perfusion increased by 24 and 35% during +1Gz and +2Gz, respectively. In the upper arm, oxygenated haemoglobin (Hb) decreased, while deoxy Hb increased with little change in total Hb. In the calf muscle, O2Hb and deoxy Hb increased, resulting in total Hb increase by 7.5 ± 1.4 and 26.6 ± 2.6 µmol/L at +1Gz and +2Gz, respectively. The dynamics of Hb increase suggests a fast and a slow component. CONCLUSION Despite transmural pressures well beyond the upper myogenic control limit, intact lower body resistance vessels withstand these pressures up to +2Gz, suggesting that myogenic control may contribute only little to increased vascular resistance. The fast component of increasing total Hb indicates microvascular blood pooling contributing to soft tissue capacitance. Future research will have to address possible alterations of these acute adaptations to gravity after deconditioning by exposure to micro-g.
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Affiliation(s)
- H Habazettl
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany. .,German Heart Institute Berlin, Berlin, Germany. .,Center for Space Medicine Berlin, Berlin, Germany.
| | - Alexander Stahn
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany.,Center for Space Medicine Berlin, Berlin, Germany
| | - Andrea Nitsche
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Michael Nordine
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany.,Center for Space Medicine Berlin, Berlin, Germany
| | - A R Pries
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany.,Center for Cardiovascular Research, Charité-University Medicine Berlin, Berlin, Germany
| | - H-C Gunga
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany.,Center for Space Medicine Berlin, Berlin, Germany
| | - O Opatz
- Institute of Physiology, Charité-University Medicine Berlin, Charitéplatz 1, 10117, Berlin, Germany.,Center for Space Medicine Berlin, Berlin, Germany
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The impact of orthostatic challenge on arteriovenous hemodynamics and volume changes of the lower extremity. J Vasc Surg Venous Lymphat Disord 2013; 1:250-6. [DOI: 10.1016/j.jvsv.2012.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 10/23/2012] [Accepted: 12/05/2012] [Indexed: 11/19/2022]
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Snyder KAM, Shamimi-Noori S, Wilson TE, Monahan KD. Age- and limb-related differences in the vasoconstrictor response to limb dependency are not mediated by a sympathetic mechanism in humans. Acta Physiol (Oxf) 2012; 205:372-80. [PMID: 22276905 DOI: 10.1111/j.1748-1716.2012.02416.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 11/30/2011] [Accepted: 01/16/2012] [Indexed: 11/30/2022]
Abstract
AIMS We tested the hypotheses that vasoconstrictor responses to limb dependency are: (i) greater in the leg than the arm, (ii) impaired with age and (iii) not sympathetically mediated. METHODS Vascular responses to limb dependency (i.e. lowering the limb from heart level to 30 cm below heart level) were determined in 17 young and 17 older adults. Indices of blood flow were obtained in the brachial and popliteal arteries (Doppler ultrasound) as well as in the cutaneous circulation (forearm and calf using laser-Doppler flowmetry). Vasoconstriction was quantified by calculating the indices of vascular resistance as height corrected mean arterial pressure/limb blood velocity or skin flux. A second group of subjects repeated the limb dependency trials after acute systemic sympathetic blockade. RESULTS Limb dependency increased vascular resistance index in the brachial artery (∆59 ± 8%; P<0.05) and popliteal artery (∆99 ± 10%; P<0.05 for change in heart level and brachial vs. popliteal) of young and older adults (∆60 + 9% brachial and ∆61 ± 7% popliteal arteries; P<0.05 for change in heart level and response in popliteal young vs. older adults). In contrast, cutaneous vasoconstrictor responses to limb dependency were similar in the forearm (∆218 ± 29% and ∆200 ± 29% for young and older adults, respectively) and calf (∆257 ± 32% and ∆236 ± 29%; all P<0.05 from heart level) of young and older adults. Vasoconstrictor responses to limb dependency were not affected by sympathetic blockade in young or older adults. CONCLUSION These findings indicate that age-, limb-, and tissue-related differences may exist in the vasoconstrictor response to limb dependency in healthy humans, which are not sympathetically mediated.
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Affiliation(s)
- K. A. M. Snyder
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
| | - S. Shamimi-Noori
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
| | - T. E. Wilson
- Departments of Biomedical Sciences & of Specialty Medicine; Ohio University Heritage College of Osteopathic Medicine; Athens; OH; USA
| | - K. D. Monahan
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
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Groothuis JT, Esselink RAJ, Seeger JPH, van Aalst MJH, Hopman MTE, Bloem BR. Lower vascular tone and larger plasma volume in Parkinson's disease with orthostatic hypotension. J Appl Physiol (1985) 2011; 111:443-8. [DOI: 10.1152/japplphysiol.00069.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pathophysiology of orthostatic hypotension in Parkinson's disease (PD) is incompletely understood. The primary focus has thus far been on failure of the baroreflex, a central mediated vasoconstrictor mechanism. Here, we test the role of two other possible factors: 1) a reduced peripheral vasoconstriction (which may contribute because PD includes a generalized sympathetic denervation); and 2) an inadequate plasma volume (which may explain why plasma volume expansion can manage orthostatic hypotension in PD). We included 11 PD patients with orthostatic hypotension (PD + OH), 14 PD patients without orthostatic hypotension (PD − OH), and 15 age-matched healthy controls. Leg blood flow was examined using duplex ultrasound during 60° head-up tilt. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. In a subset of 9 PD + OH, 9 PD − OH, and 8 controls, plasma volume was determined by indicator dilution method with radiolabeled albumin (125I-HSA). The basal leg vascular resistance was significantly lower in PD + OH (0.7 ± 0.3 mmHg·ml−1·min) compared with PD − OH (1.3 ± 0.6 mmHg·ml−1·min, P < 0.01) and controls (1.3 ± 0.5 mmHg·ml−1·min, P < 0.01). Leg vascular resistance increased significantly during 60° head-up tilt with no significant difference between the groups. Plasma volume was significantly larger in PD + OH (3,869 ± 265 ml) compared with PD − OH (3,123 ± 377 ml, P < 0.01) and controls (3,204 ± 537 ml, P < 0.01). These results indicate that PD + OH have a lower basal leg vascular resistance in combination with a larger plasma volume compared with PD − OH and controls. Despite the increase in leg vascular resistance during 60° head-up tilt, PD + OH are unable to maintain their blood pressure.
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Affiliation(s)
- J. T. Groothuis
- Department of 1Physiology and
- Department of Rehabilitation, Sint Maartenskliniek, Nijmegen, The Netherlands
| | - R. A. J. Esselink
- Parkinson Centre Nijmegen, Department of Neurology, Donders Centre for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Centre, Nijmegen; and
| | | | | | | | - B. R. Bloem
- Parkinson Centre Nijmegen, Department of Neurology, Donders Centre for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Centre, Nijmegen; and
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