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Salman IM. Key challenges in exploring the rat as a preclinical neurostimulation model for aortic baroreflex modulation in hypertension. Hypertens Res 2024; 47:399-415. [PMID: 37919429 DOI: 10.1038/s41440-023-01486-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Abstract
Electrode-based electrophysiological interfaces with peripheral nerves have come a long way since the 1960s, with several neurostimulation applications witnessing widespread clinical implementation since then. In resistant hypertension, previous clinical trials have shown that "carotid" baroreflex stimulation using device-based baroreflex activation therapy (BAT) can effectively lower blood pressure (BP). However, device-based "aortic" baroreflex stimulation remains untouched for clinical translation. The rat is a remarkable animal model that facilitates exploration of mechanisms pertaining to the baroreceptor reflex and preclinical development of novel therapeutic strategies for BP modulation and hypertension treatment. Specifically, the aortic depressor nerve (ADN) in rats carries a relatively pure population of barosensitive afferent neurons, which enable selective investigation of the aortic baroreflex function. In a rat model of essential hypertension, the spontaneously hypertensive rat (SHR), we have recently investigated the aortic baroreceptor afferents as an alternate target for BP modulation, and showed that "low intensity" stimulation is able to evoke clinically meaningful reductions in BP. Deriving high quality short-term and long-term data on aortic baroreflex modulation in rats is currently hampered by a number of unresolved experimental challenges, including anatomical variations across rats which complicates identification of the ADN, the use of unrefined neurostimulation tools or paradigms, and issues arising from anesthetized and conscious surgical preparations. With the goal of refining existing experimental protocols designed for preclinical investigation of the baroreflex, this review seeks to outline current challenges hindering further progress in aortic baroreflex modulation studies in rats and present some practical considerations and recently emerging ideas to overcome them. Aortic baroreflex modulation.
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Affiliation(s)
- Ibrahim M Salman
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia.
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Salman IM. Differential frequency-dependent reflex summation of the aortic baroreceptor afferent input. Pflugers Arch 2023:10.1007/s00424-023-02820-0. [PMID: 37219603 DOI: 10.1007/s00424-023-02820-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/24/2023]
Abstract
Reflex summation in the expression of left and right aortic baroreflex control of hemodynamic functions was investigated. In anesthetized Sprague-Dawley rats, mean arterial pressure (MAP), heart rate (HR), and mesenteric vascular resistance (MVR) were recorded following left, right, and bilateral stimulation of the aortic depressor nerve (ADN). Stimulation frequency was varied between low (1 Hz), moderate (5 Hz), and high (20 Hz). At 1 Hz, left and right ADN stimulation evoked similar depressor, bradycardic and MVR responses, whereas bilateral stimulation induced larger MAP, HR, and MVR reductions compared with stimulations of either side. The sum of the separate and combined stimulation effects on MAP, HR, and MVR was similar, indicating an additive summation. A similar additive summation was observed with HR responses at 5 and 20 Hz. Left-sided and bilateral stimulation produced greater depressor and MVR responses than right-sided stimulation, with responses of the bilateral stimulation mimicking those of the left side. The bilateral MAP or MVR response was smaller than the sum of the separate responses, suggesting an inhibitory summation. In conclusion, reflex summation of the left and right aortic baroreceptor afferent input is differentially expressed in relation to the frequency of the input signal. Summation of baroreflex control of HR is always additive and independent of stimulation frequency. Summation of baroreflex control of MAP is additive when the frequency input is small and inhibitory when the frequency input is moderate to high, with MAP changes mainly driven by parallel baroreflex-triggered changes in vascular resistance.
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Affiliation(s)
- Ibrahim M Salman
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, 11533, Saudi Arabia.
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Salgado HC, Brognara F, Ribeiro AB, Lataro RM, Castania JA, Ulloa L, Kanashiro A. Autonomic Regulation of Inflammation in Conscious Animals. Neuroimmunomodulation 2023; 30:102-112. [PMID: 37232031 DOI: 10.1159/000530908] [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: 01/10/2023] [Accepted: 04/20/2023] [Indexed: 05/27/2023] Open
Abstract
Bioelectronic medicine is a novel field in modern medicine based on the specific neuronal stimulation to control organ function, cardiovascular, and immune homeostasis. However, most studies addressing neuromodulation of the immune system have been conducted on anesthetized animals, which can affect the nervous system and neuromodulation. Here, we review recent studies involving conscious experimental rodents (rats and mice) to better understand the functional organization of neural control of immune homeostasis. We highlight typical experimental models of cardiovascular regulation, such as electrical activation of the aortic depressor nerve or the carotid sinus nerve, bilateral carotid occlusion, the Bezold-Jarisch reflex, and intravenous administration of the bacterial endotoxin lipopolysaccharide. These models have been used to investigate the relationship between neuromodulation of the cardiovascular and immune systems in conscious rodents (rats and mice). These studies provide critical information about the neuromodulation of the immune system, particularly the role of the autonomic nervous system, i.e., the sympathetic and parasympathetic branches acting both centrally (hypothalamus, nucleus ambiguus, nucleus tractus solitarius, caudal ventrolateral medulla, and rostral ventrolateral medulla), and peripherally (particularly spleen and adrenal medulla). Overall, the studies in conscious experimental models have certainly highlighted to the reader how the methodological approaches used to investigate cardiovascular reflexes in conscious rodents (rats and mice) can also be valuable for investigating the neural mechanisms involved in inflammatory responses. The reviewed studies have clinical implications for future therapeutic approaches of bioelectronic modulation of the nervous system to control organ function and physiological homeostasis in conscious physiology.
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Affiliation(s)
- Helio Cesar Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Fernanda Brognara
- Department of Nursing, General and Specialized, Nursing School of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | | | - Renata Maria Lataro
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Jaci Airton Castania
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Luis Ulloa
- Department of Anesthesiology, Center for Perioperative Organ Protection, Duke University Medical Center, Durham, North Carolina, USA
| | - Alexandre Kanashiro
- Department of Dermatology, School of Medicine and Public Health, University of Wisconsin Medical Sciences Center, Madison, Wisconsin, USA
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O'Leary DS, Mannozzi J, Augustyniak RA, Ichinose M, Spranger MD. Hypertension depresses arterial baroreflex control of both heart rate and cardiac output during rest, exercise, and metaboreflex activation. Am J Physiol Regul Integr Comp Physiol 2022; 323:R720-R727. [PMID: 36121147 PMCID: PMC9602692 DOI: 10.1152/ajpregu.00093.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/24/2022] [Accepted: 09/08/2022] [Indexed: 01/19/2023]
Abstract
Rapid regulation of arterial blood pressure on a beat-by-beat basis occurs primarily via arterial baroreflex control of cardiac output (CO) via rapid changes in heart rate (HR). Previous studies have shown that changes in HR do not always cause changes in CO, because stroke volume may vary. Whether these relationships are altered in hypertension is unknown. Using the spontaneous baroreflex sensitivity (SBRS) approach, we investigated whether baroreflex control of HR and CO were impaired after the induction of hypertension in conscious, chronically instrumented canines at rest, during mild exercise, and during exercise with metaboreflex activation (induced via reductions in hindlimb blood flow) both before and after induction of hypertension (induced via a modified Goldblatt approach-unilateral reduction in renal blood flow to ∼30% of control values until systolic pressure ≥ 140 mmHg and a diastolic pressure ≥ 90 mmHg for >30 days). After induction of hypertension, SBRS control of both HR and CO was reduced in all settings. In control, only about 50% of SBRS changes in HR caused changes in CO. This pattern was sustained in hypertension. Thus, in hypertension, the reduced SBRS in the control of HR caused reduced SBRS control of CO and this likely contributes to the increased incidence of orthostatic hypotension seen in hypertensive patients.
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Affiliation(s)
- Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Robert A Augustyniak
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
| | - Marty D Spranger
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Low intensity stimulation of aortic baroreceptor afferent fibers as a potential therapeutic alternative for hypertension treatment. Sci Rep 2022; 12:12242. [PMID: 35851099 PMCID: PMC9293925 DOI: 10.1038/s41598-022-15761-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 06/29/2022] [Indexed: 11/17/2022] Open
Abstract
Carotid baroreceptor stimulation has been clinically explored for antihypertensive benefits, but neuromodulation of aortic baroreceptor afferents remains unexplored for potential translation into the clinic. Published studies have used supramaximal stimulations, which are unphysiological and energy inefficient. The objective of the present study was to identify optimal low-charge nerve stimulation parameters that would provide a clinically-relevant (20–30 mmHg) decrease in mean arterial pressure (MAP) in anesthetized spontaneously hypertensive rats. Stimulations of 20 s were delivered to the left aortic depressor nerve (ADN) of these rats using low ranges of pulse amplitudes (≤ 0.6 mA), widths (≤ 0.5 ms) and frequencies (≤ 5 Hz). We also assessed the effects of continuous (20 s) versus intermittent (5 s ON/3 s OFF and 5 s ON/3 s OFF for 20 s) stimulation on MAP, heart rate (HR), mesenteric (MVR) and femoral (FVR) vascular resistance using low (5 Hz) and high (15 Hz) frequencies. Lower pulse amplitudes (0.2 mA) produced 9 ± 2 to 18 ± 2 mmHg decreases in MAP. Higher pulse amplitudes (0.4 mA) produced a median MAP reduction of 28 ± 4 mmHg at 0.2 ms and 5 Hz, with no added benefit seen above 0.4 mA. Continuous and intermittent low frequency stimulation at 0.4 mA and 0.2 ms produced similar sustained decreases in MAP, HR, MVR and FVR. Continuous high frequency stimulation at 0.4 mA and 0.2 ms produced larger reductions in MAP, HR, MVR and FVR compared with all low frequency and/or intermittent high frequency stimulations. We conclude from these findings that “low intensity intermittent” electrical stimulation is an effective alternate way for neuromodulation of the aortic baroreceptor afferents and to evoke a required restoration of MAP levels in spontaneously hypertensive rats. This approach enables low energy consumption and markedly lowers the excessive decreases in MAP and hemodynamic disturbances elicited by continuous high-charge injection protocols.
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Cavalcante GL, Brognara F, Oliveira LVDC, Lataro RM, Durand MDT, Oliveira AP, Nóbrega ACL, Salgado HC, Sabino JPJ. Benefits of pharmacological and electrical cholinergic stimulation in hypertension and heart failure. Acta Physiol (Oxf) 2021; 232:e13663. [PMID: 33884761 DOI: 10.1111/apha.13663] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/12/2021] [Accepted: 04/06/2021] [Indexed: 12/11/2022]
Abstract
Systemic arterial hypertension and heart failure are cardiovascular diseases that affect millions of individuals worldwide. They are characterized by a change in the autonomic nervous system balance, highlighted by an increase in sympathetic activity associated with a decrease in parasympathetic activity. Most therapeutic approaches seek to treat these diseases by medications that attenuate sympathetic activity. However, there is a growing number of studies demonstrating that the improvement of parasympathetic function, by means of pharmacological or electrical stimulation, can be an effective tool for the treatment of these cardiovascular diseases. Therefore, this review aims to describe the advances reported by experimental and clinical studies that addressed the potential of cholinergic stimulation to prevent autonomic and cardiovascular imbalance in hypertension and heart failure. Overall, the published data reviewed demonstrate that the use of central or peripheral acetylcholinesterase inhibitors is efficient to improve the autonomic imbalance and hemodynamic changes observed in heart failure and hypertension. Of note, the baroreflex and the vagus nerve activation have been shown to be safe and effective approaches to be used as an alternative treatment for these cardiovascular diseases. In conclusion, pharmacological and electrical stimulation of the parasympathetic nervous system has the potential to be used as a therapeutic tool for the treatment of hypertension and heart failure, deserving to be more explored in the clinical setting.
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Affiliation(s)
- Gisele L. Cavalcante
- Graduate Program in Pharmaceutical Sciences Department of Biophysics and Physiology Federal University of Piaui Teresina PI Brazil
- Department of Pharmacology Ribeirão Preto Medical School University of São Paulo Ribeirão Preto SP Brazil
| | - Fernanda Brognara
- Department of Physiology Ribeirão Preto Medical School University of São Paulo Ribeirão Preto SP Brazil
| | - Lucas Vaz de C. Oliveira
- Graduate Program in Pharmaceutical Sciences Department of Biophysics and Physiology Federal University of Piaui Teresina PI Brazil
| | - Renata M. Lataro
- Department of Physiological Sciences Center of Biological Sciences Federal University of Santa Catarina Florianópolis SP Brazil
| | | | - Aldeidia P. Oliveira
- Graduate Program in Pharmacology Department of Biophysics and Physiology Federal University of Piaui Teresina PI Brazil
| | | | - Helio C. Salgado
- Department of Physiology Ribeirão Preto Medical School University of São Paulo Ribeirão Preto SP Brazil
| | - João Paulo J. Sabino
- Graduate Program in Pharmaceutical Sciences Department of Biophysics and Physiology Federal University of Piaui Teresina PI Brazil
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Plachta DTT, Zentner J, Aguirre D, Cota O, Stieglitz T, Gierthmuehlen M. Effect of Cardiac-Cycle-Synchronized Selective Vagal Stimulation on Heart Rate and Blood Pressure in Rats. Adv Ther 2016; 33:1246-61. [PMID: 27220533 DOI: 10.1007/s12325-016-0348-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Activation of the baroreflex system through the selective vagal nerve stimulation (sVNS) may become a treatment option for therapy-resistant hypertension, which is a frequently observed problem in the antihypertensive therapy. In previous studies, we used continuous sVNS to lower blood pressure (BP) without major side effects in a rat model. As continuous stimulation is energy consuming and sVNS could be implemented in an antihypertensive stimulator, it was the aim of this study to investigate the efficacy of pulsatile, cardiac-cycle-synchronized sVNS (cssVNS) on the reduction of BP. METHODS A multichannel cuff electrode was wrapped around the left vagal nerve in six male Wistar rats under Isoflurane anesthesia. BP was recorded in the left carotid artery. An electrocardiogram (ECG) was obtained via subcutaneous needle electrodes. The aortic depressor nerve fibers in the vagal nerve bundle were selectively stimulated with 18 parameter settings within a window of 15-30 ms after the R-peak in the ECG. The stimulation paradigm included every heartbeat, every second heart beat, and every third heart beat. BP and heart rate were initially recorded over 10 min. RESULTS Using cssVNS, BP could be significantly reduced over 30 min and maintained at this level. While the highest BP reduction was seen during cssVNS at every heartbeat with minimal bradycardia, less-yet significant-BP reduction was seen during cssVNS at every second or third heartbeat without causing detectable bradycardia. CONCLUSION cssVNS can chronically reduce BP in rats avoiding measurable bradycardic side effects. This energy-efficient technique might allow the implementation of sVNS using an implantable device to permanently lower BP in patients. FUNDING The study was funded by Bundesministerium fur Bildung und Forschung/German Federal Ministry of Education and Research among the call "Individualisierte Medizintechnik" under the grant number FKZ 13GW0120B.
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Affiliation(s)
- Dennis T T Plachta
- Department of Neurosurgery, Medical Center, Faculty of Medicine, University of Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany
| | - Josef Zentner
- Department of Neurosurgery, Medical Center, Faculty of Medicine, University of Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany
| | - Debora Aguirre
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 106, 79110, Freiburg, Germany
| | - Oscar Cota
- Neuroloop GmbH, Engesserstr. 4, 79108, Freiburg, Germany
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 106, 79110, Freiburg, Germany
| | - Mortimer Gierthmuehlen
- Department of Neurosurgery, Medical Center, Faculty of Medicine, University of Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany.
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Gierthmuehlen M, Aguirre D, Cota O, Zentner J, Stieglitz T, Plachta DTT. Influence of Clonidine on Antihypertensive Selective Afferent Vagal Nerve Stimulation in Rats. Neuromodulation 2016; 19:597-606. [DOI: 10.1111/ner.12463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 04/22/2016] [Accepted: 05/09/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Mortimer Gierthmuehlen
- Department of Neurosurgery; Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg; Germany
| | - Debora Aguirre
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK; University of Freiburg; Freiburg Germany
- Neuroloop GmbH; Freiburg Germany
| | - Oscar Cota
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK; University of Freiburg; Freiburg Germany
- Neuroloop GmbH; Freiburg Germany
| | - Josef Zentner
- Department of Neurosurgery; Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg; Germany
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK; University of Freiburg; Freiburg Germany
| | - Dennis T. T. Plachta
- Department of Neurosurgery; Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg; Germany
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK; University of Freiburg; Freiburg Germany
- Neuroloop GmbH; Freiburg Germany
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Pinto TOCT, Lataro RM, Castania JA, Durand MT, Silva CAA, Patel KP, Fazan R, Salgado HC. Electrical stimulation of the aortic depressor nerve in conscious rats overcomes the attenuation of the baroreflex in chronic heart failure. Am J Physiol Regul Integr Comp Physiol 2016; 310:R612-8. [DOI: 10.1152/ajpregu.00392.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/14/2016] [Indexed: 11/22/2022]
Abstract
Chronic heart failure (CHF) is characterized by autonomic dysfunction combined with baroreflex attenuation. The hypotensive and bradycardic responses produced by electrical stimulation of the aortic depressor nerve (ADN) were examined in conscious CHF and control male Wistar rats (12–13 wk old). Furthermore, the role of parasympathetic and sympathetic nervous system in mediating the cardiovascular responses to baroreflex activation was evaluated by selective β1-adrenergic and muscarinic receptor antagonists. CHF was induced by myocardial infarction. After 6 wk, the subjects were implanted with electrodes for ADN stimulation. Twenty-four hours later, electrical stimulation of the ADN was applied for 20 s using five different frequencies (5, 15, 30, 60, and 90 Hz), while the arterial pressure was recorded by a catheter implanted into the femoral artery. Electrical stimulation of the ADN elicited progressive and similar hypotensive and bradycardic responses in control ( n = 12) and CHF ( n = 11) rats, while the hypotensive response was not affected by methylatropine. Nevertheless, the reflex bradycardia was attenuated by methylatropine in control, but not in CHF rats. Atenolol did not affect the hypotensive or bradycardic response in either group. The ADN function was examined under anesthesia through electroneurographic recordings. The arterial pressure-ADN activity relationship was attenuated in CHF rats. In conclusion, despite the attenuation of baroreceptor function in CHF rats, the electrical stimulation of the ADN elicited a stimulus-dependent hypotension and bradycardia of similar magnitude as observed in control rats. Therefore, electrical activation of the aortic baroreflex overcomes both the attenuation of parasympathetic function and the sympathetic overdrive.
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Affiliation(s)
- Tomás O. C. Teixeira Pinto
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Renata M. Lataro
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Jaci A. Castania
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Marina T. Durand
- Department of Medicine, University of Ribeirão Preto, Ribeirão Preto, São Paulo, Brazil; and
| | - Carlos A. A. Silva
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Kaushik P. Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Rubens Fazan
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Helio C. Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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Brognara F, Dias DPM, Castania JA, Fazan R, Lewis SJ, Salgado HC. Cardiovascular responses elicited by continuous versus intermittent electrical stimulation of the aortic depressor nerve in conscious rats. Life Sci 2016; 148:99-105. [PMID: 26876918 DOI: 10.1016/j.lfs.2016.02.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 01/29/2016] [Accepted: 02/08/2016] [Indexed: 12/01/2022]
Abstract
AIMS Short-term (seconds or minutes) continuous electrical activation of the aortic depressor nerve (ADN) in conscious rats has been successfully used to investigate baroafferent function in experimental hypertension, heart failure, and peripheral inflammation. The aim of this study was to characterize the hemodynamic responses elicited by longer periods (60min) of continuous or intermittent electrical baroreflex activation. MAIN METHODS Wistar rats were implanted with an electrode around the left ADN and a catheter into a femoral artery. The systolic, diastolic and mean arterial pressure and heart rate were recorded in subjects randomly assigned to continuous or intermittent electrical stimulation. The time-course of cardiovascular responses in conscious rats was examined during longer-term (60min) continuous (n=6) or intermittent (5s ON/3s OFF; n=10) electrical stimulation (0.5mA; 0.25ms; 30Hz) of the ADN. KEY FINDINGS The prompt (20s) hypotensive response was greater under continuous stimulation, but no difference was detected in the bradycardic response. The hypotensive response was sustained only by continuous stimulation while no sustained bradycardia was observed in either protocol. SIGNIFICANCE These findings indicate that continuous stimulation of the ADN is more effective in reducing arterial pressure over a longer period (60min) of stimulation. Nevertheless, both protocols - continuous or intermittent - were unable to elicit a sustained bradycardia.
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Affiliation(s)
- Fernanda Brognara
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Daniel P Martins Dias
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jaci A Castania
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Rubens Fazan
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Stephen J Lewis
- Department of Pediatrics, Division of Pulmonology, Allergy and Immunology, Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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Bassi GS, Brognara F, Castania JA, Talbot J, Cunha TM, Cunha FQ, Ulloa L, Kanashiro A, Dias DPM, Salgado HC. Baroreflex activation in conscious rats modulates the joint inflammatory response via sympathetic function. Brain Behav Immun 2015; 49:140-7. [PMID: 25986215 PMCID: PMC7023897 DOI: 10.1016/j.bbi.2015.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 05/07/2015] [Accepted: 05/10/2015] [Indexed: 12/19/2022] Open
Abstract
The baroreflex is a critical physiological mechanism controlling cardiovascular function by modulating both the sympathetic and parasympathetic activities. Here, we report that electrical activation of the baroreflex attenuates joint inflammation in experimental arthritis induced by the administration of zymosan into the femorotibial cavity. Baroreflex activation combined with lumbar sympathectomy, adrenalectomy, celiac subdiaphragmatic vagotomy or splenectomy dissected the mechanisms involved in the inflammatory modulation, highlighting the role played by sympathetic inhibition in the attenuation of joint inflammation. From the immunological standpoint, baroreflex activation attenuates neutrophil migration and the synovial levels of inflammatory cytokines including TNF, IL-1β and IL-6, but does not affect the levels of the anti-inflammatory cytokine IL-10. The anti-inflammatory effects of the baroreflex system are not mediated by IL-10, the vagus nerve, adrenal glands or the spleen, but by the inhibition of the sympathetic drive to the knee. These results reveal a novel physiological neuronal network controlling peripheral local inflammation.
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Affiliation(s)
- Gabriel S. Bassi
- Departments of Immunology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Fernanda Brognara
- Departments of Physiology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jaci A. Castania
- Departments of Physiology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jhimmy Talbot
- Departments of Pharmacology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Thiago M. Cunha
- Departments of Immunology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil,Departments of Pharmacology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Fernando Q. Cunha
- Departments of Immunology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil,Departments of Pharmacology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luis Ulloa
- Rutgers University – New Jersey Medical School, Newark, NJ 07103, USA
| | - Alexandre Kanashiro
- Departments of Pharmacology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Daniel P. Martins Dias
- Departments of Physiology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Helio C. Salgado
- Departments of Physiology from the Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil,Corresponding author at: Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, 14049-900 Ribeirão Preto, SP, Brazil. Tel.: +55 16 33153201. (H.C. Salgado)
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Plachta DTT, Gierthmuehlen M, Cota O, Espinosa N, Boeser F, Herrera TC, Stieglitz T, Zentner J. Blood pressure control with selective vagal nerve stimulation and minimal side effects. J Neural Eng 2014; 11:036011. [PMID: 24809832 DOI: 10.1088/1741-2560/11/3/036011] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Hypertension is the largest threat to patient health and a burden to health care systems. Despite various options, 30% of patients do not respond sufficiently to medical treatment. Mechanoreceptors in the aortic arch relay blood pressure (BP) levels through vagal nerve (VN) fibers to the brainstem and trigger the baroreflex, lowering the BP. Selective electrical stimulation of these nerve fibers reduced BP in rats. However, there is no technique described to localize and stimulate these fibers inside the VN without inadvertent stimulation of non-baroreceptive fibers causing side effects like bradycardia and bradypnea. APPROACH We present a novel method for selective VN stimulation to reduce BP without the aforementioned side effects. Baroreceptor compound activity of rat VN (n = 5) was localized using a multichannel cuff electrode, true tripolar recording and a coherent averaging algorithm triggered by BP or electrocardiogram. MAIN RESULTS Tripolar stimulation over electrodes near the barofibers reduced the BP without triggering significant bradycardia and bradypnea. The BP drop was adjusted to 60% of the initial value by varying the stimulation pulse width and duration, and lasted up to five times longer than the stimulation. SIGNIFICANCE The presented method is robust to impedance changes, independent of the electrode's relative position, does not compromise the nerve and can run on implantable, ultra-low power signal processors.
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Affiliation(s)
- Dennis T T Plachta
- Department of Microsystems Engineering (IMTEK), Laboratory for Biomedical Microtechnology, University of Freiburg, Georges-Koehler-Allee 102, D-79110 Freiburg, Germany
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