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Watanabe H, Saito S, Washio T, Bailey DM, Ogoh S. Acute Gravitational Stress Selectively Impairs Dynamic Cerebrovascular Reactivity in the Anterior Circulation Independent of Changes to the Central Respiratory Chemoreflex. Front Physiol 2022; 12:749255. [PMID: 35069233 PMCID: PMC8770752 DOI: 10.3389/fphys.2021.749255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 12/03/2021] [Indexed: 11/13/2022] Open
Abstract
Cerebrovascular reactivity (CVR) to changes in the partial pressure of arterial carbon dioxide (PaCO2) is an important mechanism that maintains CO2 or pH homeostasis in the brain. To what extent this is influenced by gravitational stress and corresponding implications for the regulation of cerebral blood flow (CBF) remain unclear. The present study examined the onset responses of pulmonary ventilation (V̇E) and anterior middle (MCA) and posterior (PCA) cerebral artery mean blood velocity (Vmean) responses to acute hypercapnia (5% CO2) to infer dynamic changes in the central respiratory chemoreflex and cerebrovascular reactivity (CVR), in supine and 50° head-up tilt (HUT) positions. Each onset response was evaluated using a single-exponential regression model consisting of the response time latency [CO2-response delay (t0)] and time constant (τ). Onset response of V̇E and PCA Vmean to changes in CO2 was unchanged during 50° HUT compared with supine (τ: V̇E, p = 0.707; PCA Vmean, p = 0.071 vs. supine) but the MCA Vmean onset response was faster during supine than during 50° HUT (τ: p = 0.003 vs. supine). These data indicate that gravitational stress selectively impaired dynamic CVR in the anterior cerebral circulation, whereas the posterior circulation was preserved, independent of any changes to the central respiratory chemoreflex. Collectively, our findings highlight the regional heterogeneity underlying CBF regulation that may have translational implications for the microgravity (and hypercapnia) associated with deep-space flight notwithstanding terrestrial orthostatic diseases that have been linked to accelerated cognitive decline and neurodegeneration.
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Affiliation(s)
- Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan
| | - Shotaro Saito
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Damian Miles Bailey
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan.,Neurovascular Research Laboratory, University of South Wales, Pontypridd, United Kingdom
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan.,Neurovascular Research Laboratory, University of South Wales, Pontypridd, United Kingdom
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Labrecque L, Burma JS, Roy MA, Smirl JD, Brassard P. Reproducibility and diurnal variation of the directional sensitivity of the cerebral pressure-flow relationship in men and women. J Appl Physiol (1985) 2021; 132:154-166. [PMID: 34855525 DOI: 10.1152/japplphysiol.00653.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. ∆MCAvT/∆MAPT and ∆PCAvT/∆MAPT were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAvT/%MAPT, %PCAvT/%MAPT). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAvT/∆MAPT (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.
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Affiliation(s)
- Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada.,Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Jonathan David Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada.,Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
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Watanabe H, Washio T, Saito S, Ogoh S. Effect of breath-hold on the responses of arterial blood pressure and cerebral blood velocity to isometric exercise. Eur J Appl Physiol 2021; 122:157-168. [PMID: 34618221 DOI: 10.1007/s00421-021-04822-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 09/25/2021] [Indexed: 12/01/2022]
Abstract
PURPOSE The present study examined the effect of breath-hold without a Valsalva maneuver during isometric exercise on arterial blood pressure (ABP) and cerebral blood flow (CBF). METHODS Twenty healthy adults (15 men and five women) randomly performed only breath-hold without a Valsalva maneuver (BH), and an isometric handgrip exercise for 30 s at 40% of individual maximal voluntary contraction with continuous breathing (IHG) and with breath-hold without the Valsalva maneuver (IHG-BH). Mean ABP (MAP) and blood velocity in the middle (MCA Vmean) and posterior cerebral arteries (PCA Vmean) were continuously measured throughout each protocol. RESULTS MAP was elevated during the IHG-BH compared with IHG (P < 0.001) and BH (P = 0.001). Similarly, both MCA Vmean and PCA Vmean were higher during IHG-BH compared with IHG and BH (all P < 0.001). Moreover, the relative change in MAP from the baseline was correlated with that in both cerebral blood velocities during the BH (MCA Vmean: r = 0.739, P < 0.001 and PCA Vmean: r = 0.570, P = 0.009) and IHG-BH (MCA Vmean: r = 0.755, P < 0.001 and PCA Vmean: r = 0.617, P = 0.003) condition, but not the IHG condition (P = 0.154 and P = 0.306). CONCLUSION These results indicate that during isometric exercise, a breath-hold enhances an exercise-induced increase in MAP and, consequently, MCA Vmean and PCA Vmean.
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Affiliation(s)
- Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Shotaro Saito
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan. .,Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK.
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Perry BG, Lucas SJE. The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise. SPORTS MEDICINE-OPEN 2021; 7:36. [PMID: 34046740 PMCID: PMC8160070 DOI: 10.1186/s40798-021-00314-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/07/2021] [Indexed: 12/18/2022]
Abstract
Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.
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Affiliation(s)
- Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences & Centre for Human Brain Health, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK
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Lie SL, Hisdal J, Høiseth LØ. Cerebral blood flow velocity during simultaneous changes in mean arterial pressure and cardiac output in healthy volunteers. Eur J Appl Physiol 2021; 121:2207-2217. [PMID: 33890157 PMCID: PMC8260418 DOI: 10.1007/s00421-021-04693-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 04/15/2021] [Indexed: 02/03/2023]
Abstract
Purpose Cerebral blood flow (CBF) needs to be precisely controlled to maintain brain functions. While previously believed to be autoregulated and near constant over a wide blood pressure range, CBF is now understood as more pressure passive. However, there are still questions regarding the integrated nature of CBF regulation and more specifically the role of cardiac output. Our aim was, therefore, to explore the effects of MAP and cardiac output on CBF in a combined model of reduced preload and increased afterload. Method 16 healthy volunteers were exposed to combinations of different levels of simultaneous lower body negative pressure and isometric hand grip. We measured blood velocity in the middle cerebral artery (MCAV) and internal carotid artery (ICAV) by Doppler ultrasound, and cerebral oxygen saturation (ScO2) by near-infrared spectroscopy, as surrogates for CBF. The effect of changes in MAP and cardiac output on CBF was estimated with mixed multiple regression. Result Both MAP and cardiac output had independent effects on MCAV, ICAV and ScO2. For ICAV and ScO2 there was also a statistically significant interaction effect between MAP and cardiac output. The estimated effect of a change of 10 mmHg in MAP on MCAV was 3.11 cm/s (95% CI 2.51–3.71, P < 0.001), and the effect of a change of 1 L/min in cardiac output was 3.41 cm/s (95% CI 2.82–4.00, P < 0.001). Conclusion The present study indicates that during reductions in cardiac output, both MAP and cardiac output have independent effects on CBF. Supplementary Information The online version contains supplementary material available at 10.1007/s00421-021-04693-6.
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Affiliation(s)
- Sole Lindvåg Lie
- Faculty of Medicine, University of Oslo, Oslo, Norway. .,Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, 0424, Oslo, Norway.
| | - Jonny Hisdal
- Faculty of Medicine, University of Oslo, Oslo, Norway.,Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, 0424, Oslo, Norway
| | - Lars Øivind Høiseth
- Department of Anesthesiology, Division of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
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Cerebrovascular haemodynamics during isometric resistance exercise with and without the Valsalva manoeuvre. Eur J Appl Physiol 2020; 120:467-479. [PMID: 31912226 DOI: 10.1007/s00421-019-04291-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/20/2019] [Indexed: 12/30/2022]
Abstract
PURPOSE To examine the interactive effects of VM and isometric resistance exercise on cerebral haemodynamics. METHODS Eleven healthy participants (mean ± SD 28 ± 9 years; 2 females) completed 20-s bilateral isometric leg extension at 50% of maximal voluntary contraction with continued ventilation (RE), a 20-s VM at mouth pressure of 40 mmHg (VM), and a combination (RE + VM), in randomised order. Mean beat-to-beat blood velocity in the posterior (PCAvmean) and middle cerebral arteries (MCAvmean), vertebral artery blood flow, end-tidal partial pressure of CO2 and mean arterial pressure (MAP) were measured. RE data were time aligned to RE + VM and analysed according to standard VM phases. RESULTS Interaction effects (VM phase × condition) were observed for MCAvmean, PCAvmean, vertebral artery blood flow and MAP (all ≤ 0.010). Phase I MCAvmean was greatest for RE [88 ± 19, vs. 71 ± 11 and 78 ± 12 cm s-1 for VM (P = 0.008) and RE + VM (P = 0.021), respectively]. Greater increases in MCAvmean than PCAvmean occurred in phase I of RE only (24 ± 15% vs. 16 ± 16%, post hoc P = 0.044). In phase IIb, MAP was lower in RE than RE + VM (115 ± 15 vs. 138 ± 21 mmHg, P = 0.004), but did not reduce MCAvmean (78 ± 8 vs. 79 ± 9 cm s-1, P = 0.579) or PCAvmean (45 ± 11 vs .46 ± 11 cm s-1, P = 0.617). Phase IIb MCAvmean and PCAvmean was lowest in VM (66 ± 6 and 39 ± 8 cm s-1, respectively, all P < 0.001), whereas in Phase IV, MCAvmean, PCAvmean and MAP were greater in VM than in RE and RE + VM (all P < 0.020). CONCLUSION RE and RE + VM produce similar cerebrovascular responses despite different MAP profiles. However, the VM produced the greatest cerebrovascular challenge afterward.
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