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Pijacka W, Katayama PL, Salgado HC, Lincevicius GS, Campos RR, McBryde FD, Paton JFR. Variable role of carotid bodies in cardiovascular responses to exercise, hypoxia and hypercapnia in spontaneously hypertensive rats. J Physiol 2018; 596:3201-3216. [PMID: 29313987 DOI: 10.1113/jp275487] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/29/2017] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Carotid bodies play a critical role in maintaining arterial pressure during hypoxia and this has important implications when considering resection therapy of the carotid body in disease states such as hypertension. Curbing hypertension in patients whether resting or under stress remains a major global health challenge. We demonstrated previously the benefits of removing carotid body afferent input into the brain for both alleviating sympathetic overdrive and reducing blood pressure in neurogenic hypertension. We describe a new approach in rats for selective ablation of the carotid bodies that spares the functional integrity of the carotid sinus baroreceptors, and demonstrate the importance of the carotid bodies in the haemodynamic response to forced exercise, hypoxia and hypercapnia in conditions of hypertension. Selective ablation reduced blood pressure in hypertensive rats and re-set baroreceptor reflex function accordingly; the increases in blood pressure seen during exercise, hypoxia and hypercapnia were unaffected, abolished and augmented, respectively, after selective carotid body removal. The data suggest that carotid body ablation may trigger potential cardiovascular risks particularly during hypoxia and hypercapnia and that suppression rather than obliteration of their activity may be a more effective and safer route to pursue. ABSTRACT The carotid body has recently emerged as a promising therapeutic target for treating cardiovascular disease, but the potential impact of carotid body removal on the dynamic cardiovascular responses to acute stressors such as exercise, hypoxia and hypercapnia in hypertension is an important safety consideration that has not been studied. We first validated a novel surgical approach to selectively resect the carotid bodies bilaterally (CBR) sparing the carotid sinus baroreflex. Second, we evaluated the impact of CBR on the cardiovascular responses to exercise, hypoxia and hypercapnia in conscious, chronically instrumented spontaneously hypertensive (SH) rats. The results confirm that our CBR technique successfully and selectively abolished the chemoreflex, whilst preserving carotid baroreflex function. CBR produced a sustained fall in arterial pressure in the SH rat of ∼20 mmHg that persisted across both dark and light phases (P < 0.001), with baroreflex function curves resetting around lower arterial pressure levels. The cardiovascular and respiratory responses to moderate forced exercise were similar between CBR and Sham rats. In contrast, CBR abolished the pressor response to hypoxia seen in Sham animals, although the increases in heart rate and respiration were similar between Sham and CBR groups. Both the pressor and the respiratory responses to 7% hypercapnia were augmented after CBR (P < 0.05) compared to sham. Our finding that the carotid bodies play a critical role in maintaining arterial pressure during hypoxia has important implications when considering resection therapy of the carotid body in disease states such as hypertension as well as heart failure with sleep apnoea.
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Affiliation(s)
- Wioletta Pijacka
- Bristol CardioNomics Group, School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Pedro L Katayama
- Bristol CardioNomics Group, School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK.,Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Gisele S Lincevicius
- Bristol CardioNomics Group, School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK.,Cardiovascular Division - Department of Physiology, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Brazil
| | - Ruy R Campos
- Cardiovascular Division - Department of Physiology, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Brazil
| | - Fiona D McBryde
- Cardiovascular Autonomic Research Cluster, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Julian F R Paton
- Bristol CardioNomics Group, School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK.,Cardiovascular Autonomic Research Cluster, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
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McBryde FD, Hart EC, Ramchandra R, Paton JF. Evaluating the carotid bodies and renal nerves as therapeutic targets for hypertension. Auton Neurosci 2017; 204:126-130. [DOI: 10.1016/j.autneu.2016.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/28/2016] [Accepted: 08/01/2016] [Indexed: 11/30/2022]
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Pijacka W, McBryde FD, Marvar PJ, Lincevicius GS, Abdala APL, Woodward L, Li D, Paterson DJ, Paton JFR. Carotid sinus denervation ameliorates renovascular hypertension in adult Wistar rats. J Physiol 2016; 594:6255-6266. [PMID: 27510951 DOI: 10.1113/jp272708] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/03/2016] [Indexed: 01/24/2023] Open
Abstract
KEY POINTS Peripheral chemoreflex sensitization is a feature of renovascular hypertension. Carotid sinus nerve denervation (CSD) has recently been shown to relieve hypertension and reduce sympathetic activity in other rat models of hypertension. We show that CSD in renovascular hypertension halts further increases in blood pressure. Possible mechanisms include improvements in baroreceptor reflex sensitivity and renal function, restoration of cardiac calcium signalling towards control levels, and reduced neural inflammation. Our data suggest that the peripheral chemoreflex may be a viable therapeutic target for renovascular hypertension. ABSTRACT The peripheral chemoreflex is known to be hyper-responsive in both spontaneously hypertensive (SHR) and Goldblatt hypertensive (two kidney one clip; 2K1C) rats. We have previously shown that carotid sinus nerve denervation (CSD) reduces arterial blood pressure (ABP) in SHR. In the present study, we show that CSD ameliorates 2K1C hypertension and reveal the potential underlying mechanisms. Adult Wistar rats were instrumented to record ABP via telemetry, and then underwent CSD (n = 9) or sham CSD (n = 9) 5 weeks after renal artery clipping, in comparison with normal Wistar rats (n = 5). After 21 days, renal function was assessed, and tissue was collected to assess sympathetic postganglionic intracellular calcium transients ([Ca2+ ]i ) and immune cell infiltrates. Hypertensive 2K1C rats showed a profound elevation in ABP (Wistar: 98 ± 4 mmHg vs. 2K1C: 147 ± 8 mmHg; P < 0.001), coupled with impairments in renal function and baroreflex sensitivity, increased neuroinflammatory markers and enhanced [Ca2+ ]I in stellate neurons (P < 0.05). CSD reduced ABP in 2K1C+CSD rats and prevented the further progressive increase in ABP seen in 2K1C+sham CSD rats, with a between-group difference of 14 ± 2 mmHg by week 3 (P < 0.01), which was accompanied by improvements in both baroreflex control and spectral indicators of cardiac sympatho-vagal balance. Furthermore, CSD improved protein and albuminuria, decreased [Ca2+ ]i evoked responses from stellate neurons, and also reduced indicators of brainstem inflammation. In summary, CSD in 2K1C rats reduces the hypertensive burden and improves renal function. This may be mediated by improvements in autonomic balance, functional remodelling of post-ganglionic neurons and reduced inflammation. Our results suggest that the peripheral chemoreflex may be considered as a potential therapeutic target for controlling renovascular hypertension.
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Affiliation(s)
- Wioletta Pijacka
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Fiona D McBryde
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK.,Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Marvar
- Department of Pharmacology and Physiology, The George Washington University School of Medical and Health Sciences, Washington, DC, USA
| | - Gisele S Lincevicius
- Cardiovascular Division - Department of Physiology, Escola Paulista de Medicina, Universidade Federal de, Sao Paulo, Brazil
| | - Ana P L Abdala
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK
| | - Lavinia Woodward
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - Dan Li
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - Julian F R Paton
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences, University of Bristol, Bristol, UK.
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Abstract
This brief review highlights new ideas about the role of the sympathetic nervous system in human blood pressure regulation. We emphasize how this role varies with age and sex and use our findings to raise questions about the sympathetic nervous system and hypertension in humans. We also focus on three additional areas, including (1) novel ideas about the carotid body and sympathoexcitation as it relates to hypertension, (2) clinical trials of renal denervation that attempted to treat hypertension by reducing ongoing sympathoexcitation, and (3) new ideas about resistant hypertension and cerebral blood flow. We further highlight that success of device-based therapy to modulate the sympathetic nervous system relies heavily on patient selection. Furthermore, data suggest that the majority of patients respond to anti-hypertensive therapy and the major cause of "resistant" hypertension is poor patient adherence. While the enthusiasm for device therapy or perhaps even "precision medicine" is high, it is likely that by far the most benefit to the most patients will occur via better screening, more aggressive therapy, and the development of strategies that improve patient adherence to medication regimens and lifestyle changes.
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Affiliation(s)
- Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, 200 1st Street SW, Rochester, MN, USA.
| | - Jacqueline K Limberg
- Department of Anesthesiology, Mayo Clinic, 200 1st Street SW, Rochester, MN, USA
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Oliveira-Sales EB, Colombari E, Abdala AP, Campos RR, Paton JFR. Sympathetic overactivity occurs before hypertension in the two-kidney, one-clip model. Exp Physiol 2015; 101:67-80. [PMID: 26537847 DOI: 10.1113/ep085390] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 11/03/2015] [Indexed: 12/21/2022]
Abstract
Our knowledge of mechanisms responsible for both the development and the maintenance of hypertension remains incomplete in the Goldblatt (two-kidney, one-clip; 2K1C) model. We tested the hypothesis that elevated sympathetic nerve activity (SNA) occurs before the onset of hypertension in 2K1C rats, considering the time course of the increase in SNA in relationship to the onset of the hypertension. We used a decorticated in situ working heart-brainstem preparation of three groups of male Wistar rats, namely sham-operated animals (SHAM, n = 7) and animals 3 weeks post-2K1C, of which some were hypertensive (2K1C-H, n = 6) and others normotensive (2K1C-N, n = 9), as determined in vivo a priori. Perfusion pressure was higher in both 2K1C groups (2K1C-H, 76 ± 1 mmHg; 2K1C-N, 74 ± 3 mmHg; versus SHAM, 60 ± 2 mmHg, P < 0.05). The SNA was significantly elevated in both 2K1C groups (2K1C-H, 47.7 ± 6.1 μV; 2K1C-N, 32.8 ± 2.8 μV; versus SHAM, 20.5 ± 2.5 μV, P < 0.05) owing to its increased respiratory modulation; the chemoreflex was augmented and baroreflex depressed. Precollicular transection reduced SNA in all groups (2K1C-H, -32.5 ± 7.5%; 2K1C-NH, -48 ± 6.9%; versus SHAM, -13.2 ± 1%, P < 0.05). Subsequent medullary spinal cord transection abolished SNA in both SHAM and 2K1C-N groups, but decreased it by only 57 ± 5.5% in 2K1C-H preparations. Thus, SNA is raised before the onset of hypertension, by the third week after renal artery clipping, and this originates, in part, from its enhanced respiratory modulation. Spinal circuits contribute to the elevation of SNA in the 2K1C model, but only after hypertension has developed.
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Affiliation(s)
- Elizabeth B Oliveira-Sales
- School of Physiology & Pharmacology, Bristol Heart Institute, University of Bristol, Bristol, UK.,Department of Physiology, Federal University of Sao Paulo, UNIFESP, SP, Brazil
| | - Eduardo Colombari
- School of Physiology & Pharmacology, Bristol Heart Institute, University of Bristol, Bristol, UK.,Department of Physiology & Pathology, School of Dentistry of Araraquara, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Ana Paula Abdala
- School of Physiology & Pharmacology, Bristol Heart Institute, University of Bristol, Bristol, UK
| | - Ruy R Campos
- Department of Physiology, Federal University of Sao Paulo, UNIFESP, SP, Brazil
| | - Julian F R Paton
- School of Physiology & Pharmacology, Bristol Heart Institute, University of Bristol, Bristol, UK
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Jordan J. Rebuttal from Jens Jordan. J Physiol 2014; 592:3945. [PMID: 25225254 DOI: 10.1113/jphysiol.2014.279711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jens Jordan
- Institute of Clinical Pharmacology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany
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Schlaich MP, Sata Y, Esler MD. Rebuttal from Markus P. Schlaich, Yusuke Sata and Murray D. Esler. J Physiol 2014; 592:3947. [PMID: 25225255 DOI: 10.1113/jphysiol.2014.279729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Markus P Schlaich
- Neurovascular Hypertension & Kidney Disease, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia Department of Cardiovascular Medicine, Alfred Hospital, Melbourne, Victoria, Australia Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Yusuke Sata
- Neurovascular Hypertension & Kidney Disease, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia
| | - Murray D Esler
- Neurovascular Hypertension & Kidney Disease, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia Department of Cardiovascular Medicine, Alfred Hospital, Melbourne, Victoria, Australia
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