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Gao Z, Namsrai B, Han Z, Joshi P, Rao JS, Ravikumar V, Sharma A, Ring HL, Idiyatullin D, Magnuson EC, Iaizzo PA, Tolkacheva EG, Garwood M, Rabin Y, Etheridge M, Finger EB, Bischof JC. Vitrification and Rewarming of Magnetic Nanoparticle-Loaded Rat Hearts. ADVANCED MATERIALS TECHNOLOGIES 2022; 7:2100873. [PMID: 35668819 PMCID: PMC9164386 DOI: 10.1002/admt.202100873] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Indexed: 05/24/2023]
Abstract
To extend the preservation of donor hearts beyond the current 4-6 h, this paper explores heart cryopreservation by vitrification-cryogenic storage in a glass-like state. While organ vitrification is made possible by using cryoprotective agents (CPA) that inhibit ice during cooling, failure occurs during convective rewarming due to slow and non-uniform rewarming which causes ice crystallization and/or cracking. Here an alternative, "nanowarming", which uses silica-coated iron oxide nanoparticles (sIONPs) perfusion loaded through the vasculature is explored, that allows a radiofrequency coil to rewarm the organ quickly and uniformly to avoid convective failures. Nanowarming has been applied to cells and tissues, and a proof of principle study suggests it is possible in the heart, but proper physical and biological characterization especially in organs is still lacking. Here, using a rat heart model, controlled machine perfusion loading and unloading of CPA and sIONPs, cooling to a vitrified state, and fast and uniform nanowarming without crystallization or cracking is demonstrated. Further, nanowarmed hearts maintain histologic appearance and endothelial integrity superior to convective rewarming and indistinguishable from CPA load/unload control hearts while showing some promising organ-level (electrical) functional activity. This work demonstrates physically successful heart vitrification and nanowarming and that biological outcomes can be expected to improve by reducing or eliminating CPA toxicity during loading and unloading.
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Affiliation(s)
- Zhe Gao
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
| | - Baterdene Namsrai
- Department of Surgery, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA
| | - Zonghu Han
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
| | - Purva Joshi
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA
| | - Joseph Sushil Rao
- Department of Surgery, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA
| | - Vasanth Ravikumar
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA
| | - Anirudh Sharma
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
| | - Hattie L Ring
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 6th Street S.E. Minneapolis, Minneapolis, MN 55455, USA
| | - Djaudat Idiyatullin
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 6th Street S.E. Minneapolis, Minneapolis, MN 55455, USA
| | - Elliott C Magnuson
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
| | - Paul A Iaizzo
- Department of Surgery, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA
| | - Elena G Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA
| | - Michael Garwood
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 6th Street S.E. Minneapolis, Minneapolis, MN 55455, USA
| | - Yoed Rabin
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA
| | - Michael Etheridge
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
| | - Erik B Finger
- Department of Surgery, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA
| | - John C Bischof
- Department of Mechanical Engineering, University of Minnesota, 111 Church St. SE., Minneapolis, MN 55455, USA
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Scalco A, Moro N, Mongillo M, Zaglia T. Neurohumoral Cardiac Regulation: Optogenetics Gets Into the Groove. Front Physiol 2021; 12:726895. [PMID: 34531763 PMCID: PMC8438220 DOI: 10.3389/fphys.2021.726895] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/27/2021] [Indexed: 12/25/2022] Open
Abstract
The cardiac autonomic nervous system (ANS) is the main modulator of heart function, adapting contraction force, and rate to the continuous variations of intrinsic and extrinsic environmental conditions. While the parasympathetic branch dominates during rest-and-digest sympathetic neuron (SN) activation ensures the rapid, efficient, and repeatable increase of heart performance, e.g., during the "fight-or-flight response." Although the key role of the nervous system in cardiac homeostasis was evident to the eyes of physiologists and cardiologists, the degree of cardiac innervation, and the complexity of its circuits has remained underestimated for too long. In addition, the mechanisms allowing elevated efficiency and precision of neurogenic control of heart function have somehow lingered in the dark. This can be ascribed to the absence of methods adequate to study complex cardiac electric circuits in the unceasingly moving heart. An increasing number of studies adds to the scenario the evidence of an intracardiac neuron system, which, together with the autonomic components, define a little brain inside the heart, in fervent dialogue with the central nervous system (CNS). The advent of optogenetics, allowing control the activity of excitable cells with cell specificity, spatial selectivity, and temporal resolution, has allowed to shed light on basic neuro-cardiology. This review describes how optogenetics, which has extensively been used to interrogate the circuits of the CNS, has been applied to untangle the knots of heart innervation, unveiling the cellular mechanisms of neurogenic control of heart function, in physiology and pathology, as well as those participating to brain-heart communication, back and forth. We discuss existing literature, providing a comprehensive view of the advancement in the understanding of the mechanisms of neurogenic heart control. In addition, we weigh the limits and potential of optogenetics in basic and applied research in neuro-cardiology.
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Affiliation(s)
- Arianna Scalco
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Nicola Moro
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Marco Mongillo
- Veneto Institute of Molecular Medicine, Padova, Italy
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Tania Zaglia
- Veneto Institute of Molecular Medicine, Padova, Italy
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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Berg K, Bjerre KP, Clemmensen TS, Løgstrup BB, Mølgaard H, Poulsen SH, Eiskjær H. Burden of arrhythmia and silent ischemia in heart transplant patients with cardiac allograft vasculopathy. SCAND CARDIOVASC J 2021; 55:300-307. [PMID: 34313167 DOI: 10.1080/14017431.2021.1955961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND The incidence of sudden cardiac death (SCD) following heart transplantation (HTx) accounts for approximately 10% of post-HTx deaths. Ischemia, brady- and tachy-arrhythmias caused by rejection and cardiac allograft vasculopathy (CAV) seem related to SCD. Hence, we aimed to investigate the relation between CAV, arrhythmias and silent ischemia in long-term HTx patients. Methods. 49 HTx patients were included. Patients were CAV classified in accordance with guidelines from the International Society of Heart and Lung Transplantation. Patients were divided into predefined CAV groups (CAV 0, CAV 1, CAV 2 + 3). Incidences of arrhythmia and silent ischemia were detected by 48-h electrocardiogram monitoring and analyzed blinded to CAV-status. Results. Median time since transplantation was 9 years [IQR 4-14]. We observed a higher incidence of non-sustained ventricular tachycardia (NSVT) in CAV 2 + 3 patients than CAV 0 and 1 patients (p = .01). Likewise, isolated premature ventricular complexes (PVC) (p = .01) and PQ-interval prolongation (p = .01) were more frequent in CAV 2 + 3 patients than CAV 0 and 1 patients. Silent ischemia was only observed among CAV 3 patients (p = .04). We saw no significant difference in the incidence of supraventricular tachycardia among CAV groups (p = .21). Likewise, no difference in the right bundle branch block was observed (p = .68). Conclusion. NSVT was associated with CAV status in long-term HTx patients. Patients with moderate to severe CAV showed higher incidences of PVCs and PQ-interval prolongation than patients with mild or no CAV. Silent ischemia was only seen in patients with severe CAV.
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Affiliation(s)
- Katrine Berg
- Department of Cardiology, Aarhus University Hospital, Aarhus N, Denmark
| | | | | | | | - Henning Mølgaard
- Department of Cardiology, Aarhus University Hospital, Aarhus N, Denmark
| | | | - Hans Eiskjær
- Department of Cardiology, Aarhus University Hospital, Aarhus N, Denmark
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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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Wang Y, Po SS, Scherlag BJ, Yu L, Jiang H. The role of low-level vagus nerve stimulation in cardiac therapy. Expert Rev Med Devices 2019; 16:675-682. [PMID: 31306049 DOI: 10.1080/17434440.2019.1643234] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Introduction: Cardiovascular diseases are accompanied by autonomic nervous system (ANS) imbalance which is characterized by decreased vagal tone. Preclinical and clinical studies have revealed that increasing vagal activity via vagus nerve stimulation (VNS) could protect the heart. Based on these studies, VNS has emerged as a potential non-pharmaceutical treatment strategy. Although it's still difficult to find the optimal stimulus parameters, however, in arrhythmia model, it is reported that low-level VNS (LL-VNS) exacts paradoxical effects from the high-level VNS. Thus, the concept of LL-VNS is introduced. Areas covered: Animal and human studies have discussed the safety and efficacy of VNS and LL-VNS, and this review will discuss the research data in cardiovascular diseases, including atrial arrhythmia, ventricular arrhythmia, ischemia/reperfusion injury, heart failure, and hypertension. Expert opinion: In this regard, various clinical studies have been performed to verify the safety and efficacy of VNS. It is shown that VNS is well-tolerated and safe, but the results of its efficacy are conflicting, which may well block the translational process of VNS. The appearance of LL-VNS brings new idea and inspiration, suggesting an important role of subthreshold stimulation. A better understanding of the LL-VNS will contribute to translational research of VNS.
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Affiliation(s)
- Yuhong Wang
- a Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University; Hubei Key Laboratory of Cardiology , Wuhan , Hubei , China.,b Key Laboratory of Myocardial Ischemia, Ministry of Education, Harbin Medical University , Harbin , China
| | - Sunny S Po
- c Heart Rhythm Institute and Department of Medicine, University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Benjamin J Scherlag
- c Heart Rhythm Institute and Department of Medicine, University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Lilei Yu
- a Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University; Hubei Key Laboratory of Cardiology , Wuhan , Hubei , China
| | - Hong Jiang
- a Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University; Hubei Key Laboratory of Cardiology , Wuhan , Hubei , China
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Annoni EM, Van Helden D, Guo Y, Levac B, Libbus I, KenKnight BH, Osborn JW, Tolkacheva EG. Chronic Low-Level Vagus Nerve Stimulation Improves Long-Term Survival in Salt-Sensitive Hypertensive Rats. Front Physiol 2019; 10:25. [PMID: 30766489 PMCID: PMC6365472 DOI: 10.3389/fphys.2019.00025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/10/2019] [Indexed: 12/31/2022] Open
Abstract
Chronic hypertension (HTN) affects more than 1 billion people worldwide, and is associated with an increased risk of cardiovascular disease. Despite decades of promising research, effective treatment of HTN remains challenging. This work investigates vagus nerve stimulation (VNS) as a novel, device-based therapy for HTN treatment, and specifically evaluates its effects on long-term survival and HTN-associated adverse effects. HTN was induced in Dahl salt-sensitive rats using a high-salt diet, and the rats were randomly divided into two groups: VNS (n = 9) and Sham (n = 8), which were implanted with functional or non-functional VNS stimulators, respectively. Acute and chronic effects of VNS therapy were evaluated through continuous monitoring of blood pressure (BP) and ECG via telemetry devices. Autonomic tone was quantified using heart rate (HR), HR variability (HRV) and baroreflex sensitivity (BRS) analysis. Structural cardiac changes were quantified through gross morphology and histology studies. VNS significantly improved the long-term survival of hypertensive rats, increasing median event-free survival by 78% in comparison to Sham rats. Acutely, VNS improved autonomic balance by significantly increasing HRV during stimulation, which may lead to beneficial chronic effects of VNS therapy. Chronic VNS therapy slowed the progression of HTN through an attenuation of SBP and by preserving HRV. Finally, VNS significantly altered cardiac structure, increasing heart weight, but did not alter the amount of fibrosis in the hypertensive hearts. These results suggest that VNS has the potential to improve outcomes in subjects with severe HTN.
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Affiliation(s)
- Elizabeth M Annoni
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Dusty Van Helden
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States
| | - Yugene Guo
- Department of Biology, University of Minnesota, Minneapolis, MN, United States
| | - Brett Levac
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN, United States
| | | | | | - John W Osborn
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States
| | - Elena G Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
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Lee SW, Anderson A, Guzman PA, Nakano A, Tolkacheva EG, Wickman K. Atrial GIRK Channels Mediate the Effects of Vagus Nerve Stimulation on Heart Rate Dynamics and Arrhythmogenesis. Front Physiol 2018; 9:943. [PMID: 30072916 PMCID: PMC6060443 DOI: 10.3389/fphys.2018.00943] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/27/2018] [Indexed: 01/09/2023] Open
Abstract
Diminished parasympathetic influence is central to the pathogenesis of cardiovascular diseases, including heart failure and hypertension. Stimulation of the vagus nerve has shown promise in treating cardiovascular disease, prompting renewed interest in understanding the signaling pathway(s) that mediate the vagal influence on cardiac physiology. Here, we evaluated the contribution of G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels to the effect of vagus nerve stimulation (VNS) on heart rate (HR), HR variability (HRV), and arrhythmogenesis in anesthetized mice. As parasympathetic fibers innervate both atria and ventricle, and GIRK channels contribute to the cholinergic impact on atrial and ventricular myocytes, we collected in vivo electrocardiogram recordings from mice lacking either atrial or ventricular GIRK channels, during VNS. VNS decreased HR and increased HRV in control mice, in a muscarinic receptor-dependent manner. This effect was preserved in mice lacking ventricular GIRK channels, but was nearly completely absent in mice lacking GIRK channels in the atria. In addition, atrial-specific ablation of GIRK channels conferred resistance to arrhythmic episodes induced by VNS. These data indicate that atrial GIRK channels are the primary mediators of the impact of VNS on HR, HRV, and arrhythmogenesis in the anesthetized mouse.
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Affiliation(s)
- Steven W. Lee
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Pilar A. Guzman
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States
| | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Elena G. Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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Kulkarni K, Xie X, Fernandez de Velasco EM, Anderson A, Martemyanov KA, Wickman K, Tolkacheva EG. The influences of the M2R-GIRK4-RGS6 dependent parasympathetic pathway on electrophysiological properties of the mouse heart. PLoS One 2018; 13:e0193798. [PMID: 29668674 PMCID: PMC5905881 DOI: 10.1371/journal.pone.0193798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/20/2018] [Indexed: 02/07/2023] Open
Abstract
A large body of work has established the prominent roles of the atrial M2R-IKACh signaling pathway, and the negative regulatory protein RGS6, in modulating critical aspects of parasympathetic influence on cardiac function, including pace-making, heart rate (HR) variability (HRV), and atrial arrhythmogenesis. Despite increasing evidence of its innervation of the ventricles, and the expression of M2R, IKACh channel subunits, and RGS6 in ventricle, the effects of parasympathetic modulation on ventricular electrophysiology are less clear. The main objective of our study was to investigate the contribution of M2R-IKACh signaling pathway elements in murine ventricular electrophysiology, using in-vivo ECG measurements, isolated whole-heart optical mapping and constitutive knockout mice lacking IKACh (Girk4–/–) or RGS6 (Rgs6-/-). Consistent with previous findings, mice lacking GIRK4 exhibited diminished HR and HRV responses to the cholinergic agonist carbachol (CCh), and resistance to CCh-induced arrhythmic episodes. In line with its role as a negative regulator of atrial M2R-IKACh signaling, loss of RGS6 correlated with a mild resting bradycardia, enhanced HR and HRV responses to CCh, and increased propensity for arrhythmic episodes. Interestingly, ventricles from mice lacking GIRK4 or RGS6 both exhibited increased action potential duration (APD) at baseline, and APD was prolonged by CCh across all genotypes. Similarly, CCh significantly increased the slope of APD restitution in all genotypes. There was no impact of genotype or CCh on either conduction velocity or heterogeneity. Our data suggests that altered parasympathetic signaling through the M2R-IKACh pathway can affect ventricular electrophysiological properties distinct from its influence on atrial physiology.
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Affiliation(s)
- Kanchan Kulkarni
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Xueyi Xie
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kirill A. Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Elena G. Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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Lee SW, Kulkarni K, Annoni EM, Libbus I, KenKnight BH, Tolkacheva EG. Stochastic vagus nerve stimulation affects acute heart rate dynamics in rats. PLoS One 2018; 13:e0194910. [PMID: 29590213 PMCID: PMC5874066 DOI: 10.1371/journal.pone.0194910] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 03/13/2018] [Indexed: 01/09/2023] Open
Abstract
Vagus nerve stimulation (VNS) is an approved therapy for treatment of epilepsy and depression. While also shown to be promising in several preclinical and clinical studies to treat cardiovascular diseases, optimal therapeutic stimulation paradigms are still under investigation. Traditionally, parameters such as frequency, current, and duty cycle are used to adjust the efficacy of VNS therapy. This study explored the effect of novel stochastic VNS (S-VNS) on acute heart rate (HR) dynamics. The effect of S-VNS was evaluated in Sprague Dawley rats by comparing the acute HR and HR variability (HRV) responses to standard, periodic VNS (P-VNS) across different frequencies (FREQs, 10-30 Hz). Our results demonstrate that both S-VNS and P-VNS produced negative chronotropic effects in a FREQ-dependent manner with S-VNS inducing a significantly smaller drop in HR at 10 Hz and 20 Hz compared to P-VNS (p<0.05). S-VNS demonstrated a FREQ-dependent drop in the SD1/SD2 ratio, a measure of HRV, which was absent in P-VNS, suggesting that S-VNS may acutely modulate the nonlinear relationship between short- and long-term HRV. In conclusion, S-VNS is a novel stimulation procedure that may provide different physiological outcomes from standard P-VNS, as indicated by our analysis of HR dynamics. Our study provides a rationale for further detailed investigations into the therapeutic potential of S-VNS as a novel neuromodulation technique.
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Affiliation(s)
- Steven W Lee
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Kanchan Kulkarni
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Elizabeth M Annoni
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Imad Libbus
- LivaNova, PLC (Cyberonics, Inc.), Houston, TX, United States of America
| | - Bruce H KenKnight
- LivaNova, PLC (Cyberonics, Inc.), Houston, TX, United States of America
| | - Elena G Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
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Expression and relevance of the G protein-gated K + channel in the mouse ventricle. Sci Rep 2018; 8:1192. [PMID: 29352184 PMCID: PMC5775354 DOI: 10.1038/s41598-018-19719-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022] Open
Abstract
The atrial G protein-gated inwardly rectifying K+ (GIRK) channel is a critical mediator of parasympathetic influence on cardiac physiology. Here, we probed the details and relevance of the GIRK channel in mouse ventricle. mRNAs for the atrial GIRK channel subunits (GIRK1, GIRK4), M2 muscarinic receptor (M2R), and RGS6, a negative regulator of atrial GIRK-dependent signaling, were detected in mouse ventricle at relatively low levels. The cholinergic agonist carbachol (CCh) activated small GIRK currents in adult wild-type ventricular myocytes that exhibited relatively slow kinetics and low CCh sensitivity; these currents were absent in ventricular myocytes from Girk1-/- or Girk4-/- mice. While loss of GIRK channels attenuated the CCh-induced shortening of action potential duration and suppression of ventricular myocyte excitability, selective ablation of GIRK channels in ventricle had no effect on heart rate, heart rate variability, or electrocardiogram parameters at baseline or after CCh injection. Additionally, loss of ventricular GIRK channels did not impact susceptibility to ventricular arrhythmias. These data suggest that the mouse ventricular GIRK channel is a GIRK1/GIRK4 heteromer, and show that while it contributes to the cholinergic suppression of ventricular myocyte excitability, this influence does not substantially impact cardiac physiology or ventricular arrhythmogenesis in the mouse.
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Somann JP, Albors GO, Neihouser KV, Lu KH, Liu Z, Ward MP, Durkes A, Robinson JP, Powley TL, Irazoqui PP. Chronic cuffing of cervical vagus nerve inhibits efferent fiber integrity in rat model. J Neural Eng 2017; 15:036018. [PMID: 29219123 DOI: 10.1088/1741-2552/aaa039] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Numerous studies of vagal nerve stimulation (VNS) have been published showing it to be a potential treatment for chronic inflammation and other related diseases and disorders. Studies in recent years have shown that electrical stimulation of the vagal efferent fibers can artificially modulate cytokine levels and reduce systematic inflammation. Most VNS research in the treatment of inflammation have been acute studies on rodent subjects. Our study tested VNS on freely moving animals by stimulating and recording from the cervical vagus with nerve cuff electrodes over an extended period of time. APPROACH We used methods of electrical stimulation, retrograde tracing (using Fluorogold) and post necropsy histological analysis of nerve tissue, flow cytometry to measure plasma cytokine levels, and MRI scanning of gastric emptying. This novel combination of methods allowed examination of physiological aspects of VNS previously unexplored. MAIN RESULTS Through our study of 53 rat subjects, we found that chronically cuffing the left cervical vagus nerve suppressed efferent Fluorogold transport in 43 of 44 animals (36 showed complete suppression). Measured cytokine levels and gastric emptying rates concurrently showed nominal differences between chronically cuffed rats and those tested with similar acute methods. Meanwhile, results of electrophysiological and histological tests of the cuffed nerves revealed them to be otherwise healthy, consistent with previous literature. SIGNIFICANCE We hypothesize that due to these unforeseen and unexplored physiological consequences of the chronically cuffed vagus nerve in a rat, that inflammatory modulation and other vagal effects by VNS may become unreliable in chronic studies. Given our findings, we submit that it would benefit the VNS community to re-examine methods used in previous literature to verify the efficacy of the rat model for chronic VNS studies.
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Affiliation(s)
- Jesse P Somann
- Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, United States of America. Center for Implantable Devices (CID), Purdue University, West Lafayette, Indiana, United States of America
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Lee S, Peh WYX, Wang J, Yang F, Ho JS, Thakor NV, Yen S, Lee C. Toward Bioelectronic Medicine-Neuromodulation of Small Peripheral Nerves Using Flexible Neural Clip. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2017; 4:1700149. [PMID: 29201608 PMCID: PMC5700646 DOI: 10.1002/advs.201700149] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 04/30/2017] [Indexed: 05/24/2023]
Abstract
Neural modulation technology and the capability to affect organ function have spawned the new field of bioelectronic medicine. Therapeutic interventions depend on wireless bioelectronic neural interfaces that can conformally and easily attach to small (few hundred micrometers) nerves located deep in the body without neural damage. Besides size, factors like flexibility and compliance to attach and adapt to visceral nerves associated moving organs are of paramount importance and have not been previously addressed. This study proposes a novel flexible neural clip (FNC) that can be used to interface with a variety of different peripheral nerves. To illustrate the flexibility of the design, this study stimulates the pelvic nerve, the vagus nerve, and branches of the sciatic nerve and evaluates the feasibility of the design in modulating the function of each of these nerves. It is found that this FNC allows fine-tuning of physiological processes such as micturition, heart rate, and muscle contractions. Furthermore, this study also tests the ability of wirelessly powered FNC to enable remote modulation of visceral pelvic nerves located deep in the body. These results show that the FNC can be used with a range of different nerves, providing one of the critical pieces in the field of bioelectronics medicines.
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Affiliation(s)
- Sanghoon Lee
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
- Center for Intelligent Sensors and MEMSNational University of Singapore4 Engineering Drive 3Singapore117576Singapore
- NUS Suzhou Research Institute (NUSRI)Industrial ParkSuzhou215123P. R. China
| | - Wendy Yen Xian Peh
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
| | - Jiahui Wang
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
- Center for Intelligent Sensors and MEMSNational University of Singapore4 Engineering Drive 3Singapore117576Singapore
- NUS Suzhou Research Institute (NUSRI)Industrial ParkSuzhou215123P. R. China
| | - Fengyuan Yang
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
| | - John S. Ho
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
| | - Nitish V. Thakor
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
- Graduate School for Integrative Science and EngineeringNational University of SingaporeSingapore117456Singapore
- Department of Biomedical EngineeringSchool of MedicineJohns Hopkins UniversityBaltimoreMD21205USA
| | - Shih‐Cheng Yen
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer EngineeringNational University of Singapore4 Engineering Drive 3Singapore117583Singapore
- Singapore Institute for Neurotechnology (SINAPSE)National University of Singapore28 Medical Drive, #05‐CORSingapore117456Singapore
- Center for Intelligent Sensors and MEMSNational University of Singapore4 Engineering Drive 3Singapore117576Singapore
- NUS Suzhou Research Institute (NUSRI)Industrial ParkSuzhou215123P. R. China
- Graduate School for Integrative Science and EngineeringNational University of SingaporeSingapore117456Singapore
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Lee SW, Li Q, Libbus I, Xie X, KenKnight BH, Garry MG, Tolkacheva EG. Chronic cyclic vagus nerve stimulation has beneficial electrophysiological effects on healthy hearts in the absence of autonomic imbalance. Physiol Rep 2016; 4:e12786. [PMID: 27173672 PMCID: PMC4873636 DOI: 10.14814/phy2.12786] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 04/13/2016] [Indexed: 11/24/2022] Open
Abstract
Cardiovascular disease degrades the regulatory function of the autonomic nervous system. Cyclic vagus nerve stimulation (VNS) is an already FDA-approved therapy for drug-resistant epilepsy and depression, and has been shown to normalize autonomic function and improve objective measures of heart function and subjective measures of heart failure symptoms. However, it remains unclear whether VNS may induce negative effects in patients with potentially healthy hearts where VNS can be used for epileptic patients. Hence, this study aims to investigate the effects of VNS on the hearts of healthy rats with normal autonomic balance. Sprague-Dawley rats were implanted with stimulators and randomized to either Sham or VNS groups. Rats in VNS group received 10 weeks of chronic intermittent VNS via stimulation of the right cervical vagus nerve. Echocardiography was performed at Baseline (prior to VNS), Week 2, and Week 9. After 10 weeks, high-resolution optical mapping was performed in ex vivo perfused hearts to evaluate the electrophysiological remodeling that occurs in the heart as a result of the VNS therapy. Chronic VNS modified the electrophysiological properties of healthy rat hearts by reducing the action potential duration at 50% (APD50) and 80% (APD80) repolarization. Chronic VNS also affected the restitution properties of the heart at the APD50 level and increased myocardial conduction velocity (CV). VNS did not induce any significant changes to ventricular ejection fraction (EF) and spatial dispersion of APD, thus indicating that VNS did not negatively affect cardiac function. VNS also reduced the susceptibility to ventricular arrhythmias (ventricular fibrillation [VF] and ventricular tachycardia [VT]) during ex vivo programmed electrical stimulation. In summary, chronic application of cyclic VNS induces changes to the electrophysiological properties of healthy rat hearts. The observed decrease in APD and increase in CV suggest that the beneficial effects of VNS do not require the presence of existing autonomic imbalance.
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Affiliation(s)
- Steven W Lee
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Qinglu Li
- Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | | | - Xueyi Xie
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Bruce H KenKnight
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota Cyberonics Inc., Houston, Texas
| | - Mary G Garry
- Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | - Elena G Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
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