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Guevara A, Smith CER, Wang L, Caldwell JL, Tapa S, Francis Stuart SD, Ma BW, Ng GA, Habecker BA, Wang Z, Ripplinger CM. Sympathetic structural and electrophysiological remodeling in a rabbit model of reperfused myocardial infarction. Am J Physiol Heart Circ Physiol 2024; 327:H631-H638. [PMID: 39028283 DOI: 10.1152/ajpheart.00398.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/16/2024] [Accepted: 07/16/2024] [Indexed: 07/20/2024]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) inhibit sympathetic reinnervation in rodent hearts post-myocardial infarction (MI), causing regional hypoinnervation that is associated with supersensitivity of β-adrenergic receptors and increased arrhythmia susceptibility. To investigate the role of CSPGs and hypoinnervation in the heart of larger mammals, we used a rabbit model of reperfused MI and tested electrophysiological responses to sympathetic nerve stimulation (SNS). Innervated hearts from MI and sham rabbits were optically mapped using voltage and Ca2+-sensitive dyes. SNS was performed with electrical stimulation of the spinal cord, and β-adrenergic responsiveness was tested using isoproterenol. Sympathetic nerve density and CSPG expression were evaluated using immunohistochemistry. CSPGs were robustly expressed in the infarct region of all MI hearts, and the presence of CSPGs was associated with reduced sympathetic nerve density in the infarct versus remote region. Action potential duration (APD) dispersion and tendency for induction of ventricular tachycardia/fibrillation (VT/VF) were increased with SNS in MI but not sham hearts. SNS decreased APD at 80% repolarization (APD80) in MI but not sham hearts, whereas isoproterenol decreased APD80 in both groups. Isoproterenol also shortened Ca2+ transient duration at 80% repolarization in both groups but to a greater extent in MI hearts. Our data suggest that sympathetic remodeling post-MI is similar between rodents and rabbits, with CSPGs associated with sympathetic hypoinnervation. Despite a reduction in sympathetic nerve density, the infarct region of MI hearts remained responsive to both physiological SNS and isoproterenol, potentially through preserved or elevated β-adrenergic responsiveness, which may underlie increased APD dispersion and tendency for VT/VF.NEW & NOTEWORTHY Here, we show that CSPGs are present in the infarcts of rabbit hearts with reperfused MI, where they are associated with reduced sympathetic nerve density. Despite hypoinnervation, sympathetic responsiveness is maintained or enhanced in MI rabbit hearts, which also demonstrate increased APD dispersion and tendency for arrhythmias following sympathetic modulation. Together, this study indicates that the mechanisms of sympathetic remodeling post-MI are similar between rodents and rabbits, with hypoinnervation likely associated with enhanced β-adrenergic sensitivity.
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Affiliation(s)
- Amanda Guevara
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Charlotte E R Smith
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Jessica L Caldwell
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Srinivas Tapa
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | | | - Betty W Ma
- Campus Veterinary Services, University of California Davis, Davis, California, United States
| | - G Andre Ng
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health & Care Research, Leicester Biomedical Research Centre, Leicester, United Kingdom
- Glenfield Hospital, Leicester, United Kingdom
| | - Beth A Habecker
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon, United States
- Department of Medicine and Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Zhen Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
- Shantou University Medical College, Shantou, China
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, United States
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Guevara A, Smith CER, Wang L, Caldwell JL, Tapa S, Stuart SDF, Ma BW, Ng GA, Habecker BA, Wang Z, Ripplinger CM. Sympathetic structural and electrophysiological remodeling in a rabbit model of reperfused myocardial infarction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.05.597494. [PMID: 38895350 PMCID: PMC11185619 DOI: 10.1101/2024.06.05.597494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) inhibit sympathetic reinnervation in rodent hearts post myocardial infarction (MI), causing regional hypo-innervation that is associated with supersensitivity of β-adrenergic receptors and increased arrhythmia susceptibility. To investigate the role of CSPGs and hypo-innervation in the heart of larger mammals, we used a rabbit model of reperfused MI and tested electrophysiological responses to sympathetic nerve stimulation (SNS). Innervated hearts from MI and sham rabbits were optically mapped using voltage and Ca 2+ -sensitive dyes. SNS was performed with electrical stimulation of the spinal cord and β-adrenergic responsiveness was tested using isoproterenol. Sympathetic nerve density and CSPG expression were evaluated using immunohistochemistry. CSPGs were robustly expressed in the infarct and border zone of all MI hearts, and the presence of CSPGs was associated with reduced sympathetic nerve density in the infarct vs. remote region. Action potential duration (APD) dispersion and susceptibility to ventricular tachycardia/fibrillation (VT/VF) were increased with SNS in MI hearts but not in sham. SNS decreased APD 80 in MI but not sham hearts, while isoproterenol decreased APD 80 in both groups. Isoproterenol also shortened Ca 2+ transient duration (CaTD 80 ) in both groups but to a greater extent in MI hearts. Our data suggest sympathetic remodeling post-MI is similar between species, with CSPGs associated with sympathetic hypo-innervation. Despite a reduction in sympathetic nerve density, the infarct region of MI hearts remained responsive to both physiological SNS and isoproterenol, potentially through preserved or elevated β-adrenergic responsiveness, which may underly increased APD dispersion and susceptibility for VT/VF. NEW & NOTEWORTHY Here we show that CSPGs are present in the infarcts of rabbit hearts with reperfused MI, where they are associated with reduced sympathetic nerve density. Despite hypo-innervation, sympathetic responsiveness is maintained or enhanced in MI rabbit hearts, which also demonstrate increased APD dispersion and tendency for arrhythmias following sympathetic modulation. Together, this study indicates that the mechanisms of sympathetic remodeling post-MI are similar between species, with hypo-innervation likely associated with enhanced β-adrenergic sensitivity.
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Guevara A, Smith CER, Caldwell JL, Ngo L, Mott LR, Lee IJ, Tapa S, Wang Z, Wang L, Woodward WR, Ng GA, Habecker BA, Ripplinger CM. Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart. Am J Physiol Heart Circ Physiol 2024; 326:H1337-H1349. [PMID: 38551482 DOI: 10.1152/ajpheart.00749.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/09/2024]
Abstract
Nicotine is the primary addictive component of tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. To assess the underlying mechanisms, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days before performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the first to third thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated following norepinephrine (NE) perfusion. Baseline ex vivo heart rate (HR) and SNS stimulation threshold were higher in NIC versus CT (P = 0.004 and P = 0.003, respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC versus CT at baseline (P = 0.002) and during SNS (P = 0.0003), with similar results obtained for Ca2+ transient alternans. SNS shortened the PCL at which alternans emerged in CT but not in NIC hearts. NIC-exposed hearts tended to have slower and reduced HR responses to NE perfusion, but ventricular responses to NE were comparable between groups. Although fibrosis was unaltered, NIC hearts had lower sympathetic nerve density (P = 0.03) but no difference in NE content versus CT. These results suggest both sympathetic hypoinnervation of the myocardium and regional differences in β-adrenergic responsiveness with NIC. This autonomic remodeling may contribute to the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with long-term use.NEW & NOTEWORTHY Here, we show that chronic nicotine exposure was associated with increased heart rate, increased susceptibility to alternans, and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to sympathetic hypoinnervation of the myocardium and diminished β-adrenergic responsiveness of the sinoatrial node following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this proarrhythmic remodeling.
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Affiliation(s)
- Amanda Guevara
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Charlotte E R Smith
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Jessica L Caldwell
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Lena Ngo
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Lilian R Mott
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - I-Ju Lee
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Srinivas Tapa
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Zhen Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
- Shantou University Medical College, Shantou, People's Republic of China
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - William R Woodward
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon, United States
| | - G Andre Ng
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health and Care Research, Leicester Biomedical Research Centre, Leicester, United Kingdom
- Glenfield Hospital, Leicester, United Kingdom
| | - Beth A Habecker
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon, United States
- Department of Medicine and Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, United States
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Haq KT, McLean K, Salameh S, Swift L, Posnack NG. Electroanatomical Adaptations in the Guinea Pig Heart from Neonatal to Adulthood. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.26.577234. [PMID: 38352347 PMCID: PMC10862765 DOI: 10.1101/2024.01.26.577234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2024]
Abstract
Background Electroanatomical adaptations during the neonatal to adult phase have not been comprehensively studied in preclinical animal models. To explore the impact of age as a biological variable on cardiac electrophysiology, we employed neonatal and adult guinea pigs, which are a recognized animal model for developmental research. Methods Healthy guinea pigs were categorized into three age groups (neonates, n=10; younger adults, n=13; and older adults, n=26). Electrocardiogram (ECG) recordings were collected in vivo from anesthetized animals (2-3% isoflurane). A Langendorff-perfusion system was employed for optical assessment of epicardial action potentials and calcium transients, using intact excised heart preparations. Optical data sets were analyzed and metric maps were constructed using Kairosight 3.0. Results The allometric relationship between heart weight and body weight diminishes with age, as it is strongest at the neonatal stage (R 2 = 0.84) and completely abolished in older adults (R 2 = 1E-06). Neonatal hearts exhibit circular activation waveforms, while adults show prototypical elliptical shapes. Neonatal conduction velocity (40.6±4.0 cm/s) is slower than adults (younger adults: 61.6±9.3 cm/s; older adults: 53.6±9.2 cm/s). Neonatal hearts have a longer action potential duration (APD) and exhibit regional heterogeneity (left apex; APD30: 68.6±5.6 ms, left basal; APD30: 62.8±3.6), which was absent in adult epicardium. With dynamic pacing, neonatal hearts exhibit a flatter APD restitution slope (APD70: 0.29±0.04) compared to older adults (0.49±0.04). Similar restitution characteristics are observed with extrasystolic pacing, with a flatter slope in neonatal hearts (APD70: 0.54±0.1) compared to adults (Younger adults: 0.85±0.4; Older adults: 0.95±0.7). Finally, neonatal hearts display unidirectional excitation-contraction coupling, while adults exhibit bidirectionality. Conclusion The transition from neonatal to adulthood in guinea pig hearts is characterized by transient changes in electroanatomic properties. Age-specific patterns can influence cardiac physiology, pathology, and therapies for cardiovascular diseases. Understanding postnatal heart development is crucial to evaluating therapeutic eligibility, safety, and efficacy. What is Known Age-specific cardiac electroanatomical characteristics have been documented in humans and some preclinical animal models. These age-specific patterns can influence cardiac physiology, pathology, and therapies for cardiovascular diseases. What the Study Adds Cardiac electroanatomical characteristics are age-specific in guinea pigs, a well-known preclinical model for developmental studies. Age-dependent adaptations in cardiac electrophysiology are readily observed in the electrocardiogram recordings and via optical mapping of epicardial action potentials and calcium transients. Our findings reveal unique activation and repolarization characteristics between neonatal and adult animals.
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Swift LM, Roberts A, Pressman J, Guerrelli D, Allen S, Haq KT, Reisz JA, D’Alessandro A, Posnack NG. Evidence for the cardiodepressive effects of the plasticizer di-2-ethylhexyl phthalate. Toxicol Sci 2023; 197:79-94. [PMID: 37812252 PMCID: PMC10734602 DOI: 10.1093/toxsci/kfad105] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023] Open
Abstract
Di-2-ethylhexyl phthalate (DEHP) is commonly used in the manufacturing of plastic materials, including intravenous bags, blood storage bags, and medical-grade tubing. DEHP can leach from plastic medical products, which can result in inadvertent patient exposure. DEHP concentrations were measured in red blood cell units stored between 7 and 42 days (17-119 μg/ml). Using these concentrations as a guide, Langendorff-perfused rat heart preparations were acutely exposed to DEHP. Sinus activity remained stable with lower doses of DEHP (25-50 μg/ml), but sinus rate declined by 43% and sinus node recovery time (SNRT) prolonged by 56.5% following 30-min exposure to 100 μg/ml DEHP. DEHP exposure also exerted a negative dromotropic response, as indicated by a 69.4% longer PR interval, 108.5% longer Wenckebach cycle length (WBCL), and increased incidence of atrioventricular (AV) uncoupling (60-min exposure). Pretreatment with doxycycline partially rescued the effects of DEHP on sinus activity, but did not ameliorate the effects on AV conduction. DEHP exposure also prolonged the ventricular action potential and effective refractory period, but had no measurable effect on intracellular calcium transient duration. Follow-up studies using human-induced pluripotent stem cell-derived cardiomyocytes confirmed that DEHP slows electrical conduction in a time (15 min-3 h) and dose-dependent manner (10-100 μg/ml). Previous studies have suggested that phthalate toxicity is specifically attributed to metabolites of DEHP, including mono-2-ethylhexylphthalate. This study demonstrates that DEHP exposure also contributes to cardiac dysfunction in a dose- and time-dependent manner. Future work is warranted to investigate the impact of DEHP (and its metabolites) on human health, with special consideration for clinical procedures that employ plastic materials.
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Affiliation(s)
- Luther M Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
| | - Anysja Roberts
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
| | - Jenna Pressman
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Department of Biomedical Engineering, School of Engineering and Applied Sciences, The George Washington University, Washington, District of Columbia 20037, USA
| | - Devon Guerrelli
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Department of Biomedical Engineering, School of Engineering and Applied Sciences, The George Washington University, Washington, District of Columbia 20037, USA
| | - Samuel Allen
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
| | - Kazi T Haq
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
| | - Julie A Reisz
- Department of Biochemistry and Molecular Genetics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Angelo D’Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, District of Columbia 20010, USA
- Department of Pediatrics, School of Medicine and Health Sciences, The George Washington University, Washington, District of Columbia 20037, USA
- Department of Pharmacology & Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, District of Columbia 20037, USA
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Iravanian S, Uzelac I, Shah AD, Toye MJ, Lloyd MS, Burke MA, Daneshmand MA, Attia TS, Vega JD, El-Chami MF, Merchant FM, Cherry EM, Bhatia NK, Fenton FH. Complex repolarization dynamics in ex vivo human ventricles are independent of the restitution properties. Europace 2023; 25:euad350. [PMID: 38006390 PMCID: PMC10751849 DOI: 10.1093/europace/euad350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 11/13/2023] [Indexed: 11/27/2023] Open
Abstract
AIMS The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts. METHODS AND RESULTS We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel. CONCLUSION We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF.
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Affiliation(s)
- Shahriar Iravanian
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Ilija Uzelac
- Georgia Institute of Technology, Department of Physics, 837 State St NW, Atlanta, GA 30332, USA
| | - Anand D Shah
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Mikael J Toye
- Georgia Institute of Technology, Department of Physics, 837 State St NW, Atlanta, GA 30332, USA
| | - Michael S Lloyd
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Michael A Burke
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Mani A Daneshmand
- Department of Surgery, Division of Cardiovascular Surgery, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Tamer S Attia
- Department of Surgery, Division of Cardiovascular Surgery, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - John David Vega
- Department of Surgery, Division of Cardiovascular Surgery, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Mikhael F El-Chami
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Faisal M Merchant
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Elizabeth M Cherry
- Georgia Institute of Technology, Department of Physics, 837 State St NW, Atlanta, GA 30332, USA
| | - Neal K Bhatia
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1364 Clifton Road, Atlanta, GA 30322, USA
| | - Flavio H Fenton
- Georgia Institute of Technology, Department of Physics, 837 State St NW, Atlanta, GA 30332, USA
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7
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Guevara A, Smith CER, Caldwell JL, Ngo L, Mott LR, Lee IJ, Tapa I, Wang Z, Wang L, Woodward WR, Ng GA, Habecker BA, Ripplinger CM. Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.23.567754. [PMID: 38045290 PMCID: PMC10690259 DOI: 10.1101/2023.11.23.567754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Nicotine is the primary addictive component in tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. However, the underlying mechanisms are unclear. To address this, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days prior to performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca 2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the 1 st - 3 rd thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated as changes in heart rate (HR) following norepinephrine (NE) perfusion. Baseline ex vivo HR and SNS stimulation threshold were increased in NIC vs. CT ( P = 0.004 and P = 0.003 respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC vs. CT at baseline ( P = 0.002) and during SNS ( P = 0.0003), with similar results obtained for Ca 2+ transient alternans. SNS reduced the PCL at which alternans emerged in CT but not NIC hearts. NIC exposed hearts also tended to have slower and reduced HR responses to NE perfusion. While fibrosis was unaltered, NIC hearts had lower sympathetic nerve density ( P = 0.03) but no difference in NE content vs. CT. These results suggest both sympathetic hypo-innervation of the myocardium and diminished β-adrenergic responsiveness with NIC. This autonomic remodeling may underlie the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with continued long-term usage. NEW & NOTEWORTHY Here we show that chronic nicotine exposure was associated with increased heart rate, lower threshold for alternans and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to the sympathetic hypo-innervation of the myocardium and diminished β- adrenergic responsiveness observed following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this pro-arrhythmic remodeling.
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8
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Zhang H, Patton HN, Wood GA, Yan P, Loew LM, Acker CD, Walcott GP, Rogers JM. Optical mapping of cardiac electromechanics in beating in vivo hearts. Biophys J 2023; 122:4207-4219. [PMID: 37775969 PMCID: PMC10645561 DOI: 10.1016/j.bpj.2023.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/31/2023] [Accepted: 09/26/2023] [Indexed: 10/01/2023] Open
Abstract
Optical mapping has been widely used in the study of cardiac electrophysiology in motion-arrested, ex vivo heart preparations. Recent developments in motion artifact mitigation techniques have made it possible to optically map beating ex vivo hearts, enabling the study of cardiac electromechanics using optical mapping. However, the ex vivo setting imposes limitations on optical mapping such as altered metabolic states, oversimplified mechanical loads, and the absence of neurohormonal regulation. In this study, we demonstrate optical electromechanical mapping in an in vivo heart preparation. Swine hearts were exposed via median sternotomy. Voltage-sensitive dye, either di-4-ANEQ(F)PTEA or di-5-ANEQ(F)PTEA, was injected into the left anterior descending artery. Fluorescence was excited by alternating green and amber light for excitation ratiometry. Cardiac motion during sinus and paced rhythm was tracked using a marker-based method. Motion tracking and excitation ratiometry successfully corrected most motion artifact in the membrane potential signal. Marker-based motion tracking also allowed simultaneous measurement of epicardial deformation. Reconstructed membrane potential and mechanical deformation measurements were validated using monophasic action potentials and sonomicrometry, respectively. Di-5-ANEQ(F)PTEA produced longer working time and higher signal/noise ratio than di-4-ANEQ(F)PTEA. In addition, we demonstrate potential applications of the new optical mapping system including electromechanical mapping during vagal nerve stimulation, fibrillation/defibrillation. and acute regional ischemia. In conclusion, although some technical limitations remain, optical mapping experiments that simultaneously image electrical and mechanical function can be conducted in beating, in vivo hearts.
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Affiliation(s)
- Hanyu Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama
| | - Haley N Patton
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama
| | - Garrett A Wood
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama
| | - Ping Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Leslie M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Corey D Acker
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Gregory P Walcott
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jack M Rogers
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama.
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9
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Christoph J, Ripplinger CM. Paralysis by analysis: Overcoming cardiac contraction with computer vision. Proc Natl Acad Sci U S A 2023; 120:e2314448120. [PMID: 37792520 PMCID: PMC10589680 DOI: 10.1073/pnas.2314448120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023] Open
Affiliation(s)
- Jan Christoph
- Cardiovascular Research Institute and Division of Cardiology, University of California, San Francisco, CA94158
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10
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Woodhams LG, Guo J, Schuftan D, Boyle JJ, Pryse KM, Elson EL, Huebsch N, Genin GM. Virtual blebbistatin: A robust and rapid software approach to motion artifact removal in optical mapping of cardiomyocytes. Proc Natl Acad Sci U S A 2023; 120:e2212949120. [PMID: 37695908 PMCID: PMC10515162 DOI: 10.1073/pnas.2212949120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 07/31/2023] [Indexed: 09/13/2023] Open
Abstract
Fluorescent reporters of cardiac electrophysiology provide valuable information on heart cell and tissue function. However, motion artifacts caused by cardiac muscle contraction interfere with accurate measurement of fluorescence signals. Although drugs such as blebbistatin can be applied to stop cardiac tissue from contracting by uncoupling calcium-contraction, their usage prevents the study of excitation-contraction coupling and, as we show, impacts cellular structure. We therefore developed a robust method to remove motion computationally from images of contracting cardiac muscle and to map fluorescent reporters of cardiac electrophysiological activity onto images of undeformed tissue. When validated on cardiomyocytes derived from human induced pluripotent stem cells (iPSCs), in both monolayers and engineered tissues, the method enabled efficient and robust reduction of motion artifact. As with pharmacologic approaches using blebbistatin for motion removal, our algorithm improved the accuracy of optical mapping, as demonstrated by spatial maps of calcium transient decay. However, unlike pharmacologic motion removal, our computational approach allowed direct analysis of calcium-contraction coupling. Results revealed calcium-contraction coupling to be more uniform across cells within engineered tissues than across cells in monolayer culture. The algorithm shows promise as a robust and accurate tool for optical mapping studies of excitation-contraction coupling in heart tissue.
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Affiliation(s)
- Louis G Woodhams
- Department of Mechanical Engineering and Material Science, Washington University in Saint Louis, St. Louis, MO 63130
| | - Jingxuan Guo
- Department of Mechanical Engineering and Material Science, Washington University in Saint Louis, St. Louis, MO 63130
| | - David Schuftan
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO 63130
| | - John J Boyle
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO 63130
| | - Kenneth M Pryse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110
| | - Elliot L Elson
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in Saint Louis, St. Louis, MO 63130
| | - Nathaniel Huebsch
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO 63130
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in Saint Louis, St. Louis, MO 63130
| | - Guy M Genin
- Department of Mechanical Engineering and Material Science, Washington University in Saint Louis, St. Louis, MO 63130
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in Saint Louis, St. Louis, MO 63130
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11
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Swift LM, Roberts A, Pressman J, Guerrelli D, Allen S, Haq KT, Reisz JA, D'Alessandro A, Posnack NG. Evidence for the cardiodepressive effects of the plasticizer di-2-ethylhexylphthalate (DEHP). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541729. [PMID: 37293060 PMCID: PMC10245927 DOI: 10.1101/2023.05.22.541729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Di-2-ethylhexylphthalate (DEHP) is commonly used in the manufacturing of plastic materials, including intravenous bags, blood storage bags, and medical-grade tubing. DEHP can leach from plastic medical products, which can result in inadvertent patient exposure. DEHP concentrations were measured in red blood cell (RBC) units stored between 7-42 days (23-119 μg/mL). Using these concentrations as a guide, Langendorff-perfused rat heart preparations were acutely exposed to DEHP. Sinus activity remained stable with lower doses of DEHP (25-50 μg/mL), but sinus rate declined by 43% and sinus node recovery time prolonged by 56.5% following 30-minute exposure to 100 μg/ml DEHP. DEHP exposure also exerted a negative dromotropic response, as indicated by a 69.4% longer PR interval, 108.5% longer Wenckebach cycle length, and increased incidence of atrioventricular uncoupling. Pretreatment with doxycycline partially rescued the effects of DEHP on sinus activity, but did not ameliorate the effects on atrioventricular conduction. DEHP exposure also prolonged the ventricular action potential and effective refractory period, but had no measurable effect on intracellular calcium transient duration. Follow-up studies using hiPSC-CM confirmed that DEHP slows electrical conduction in a time (15 min - 3 hours) and dose-dependent manner (10-100 μg/mL). Previous studies have suggested that phthalate toxicity is specifically attributed to metabolites of DEHP, including mono-2-ethylhexyl phthalate (MEHP). This study demonstrates that DEHP exposure also contributes to cardiac dysfunction in a dose- and time-dependent manner. Future work is warranted to investigate the impact of DEHP (and its metabolites) on human health, with special consideration for clinical procedures that employ plastic materials.
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12
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Haq KT, Roberts A, Berk F, Allen S, Swift LM, Posnack NG. KairoSight-3.0: A validated optical mapping software to characterize cardiac electrophysiology, excitation-contraction coupling, and alternans. JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY PLUS 2023; 5:100043. [PMID: 37786807 PMCID: PMC10544851 DOI: 10.1016/j.jmccpl.2023.100043] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Background Cardiac optical mapping is an imaging technique that measures fluorescent signals across a cardiac preparation. Dual optical imaging of voltage-sensitive and calcium-sensitive probes allows for simultaneous recordings of cardiac action potentials and intracellular calcium transients with high spatiotemporal resolution. The analysis of these complex optical datasets is both time intensive and technically challenging; as such, we have developed a software package for semi-automated image processing and analysis. Herein, we report an updated version of our software package (KairoSight-3.0) with features to enhance the characterization of cardiac parameters using optical signals. Methods To test software validity and applicability, we used Langendorff-perfused heart preparations to record transmembrane voltage and intracellular calcium signals from the epicardial surface. Isolated hearts from guinea pigs and rats were loaded with a potentiometric dye (RH237) and/or calcium indicator dye (Rhod-2AM) and fluorescent signals were acquired. We used Python 3.8.5 programming language to develop the KairoSight-3.0 software. Cardiac maps were validated with a user-specified manual mapping approach. Results Manual maps of action potential duration (30 or 80 % repolarization), calcium transient duration (30 or 80 % reuptake), action potential and calcium transient alternans were constituted to validate the accuracy of software-generated maps. Manual and software maps had high accuracy, with >97 % of manual and software values falling within 10 ms of each other and >75 % within 5 ms for action potential duration and calcium transient duration measurements (n = 1000-2000 pixels). Further, our software package includes additional measurement tools to analyze signal-to-noise ratio, conduction velocity, action potential and calcium transient alternans, and action potential-calcium transient coupling time to produce physiologically meaningful optical maps. Conclusions KairoSight-3.0 has enhanced capabilities to perform measurements of cardiac electrophysiology, calcium handling, alternans, and the excitation-contraction coupling with satisfactory accuracy.
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Affiliation(s)
- Kazi T. Haq
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Anysja Roberts
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Fiona Berk
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Department of Biomedical Engineering, School of Engineering and Applied Sciences: George Washington University, Washington, DC 20037, USA
| | - Samuel Allen
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
| | - Luther M. Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
- Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences: George Washington University, Washington, DC 20037, USA
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13
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Djemai M, Cupelli M, Boutjdir M, Chahine M. Optical Mapping of Cardiomyocytes in Monolayer Derived from Induced Pluripotent Stem Cells. Cells 2023; 12:2168. [PMID: 37681899 PMCID: PMC10487143 DOI: 10.3390/cells12172168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023] Open
Abstract
Optical mapping is a powerful imaging technique widely adopted to measure membrane potential changes and intracellular Ca2+ variations in excitable tissues using voltage-sensitive dyes and Ca2+ indicators, respectively. This powerful tool has rapidly become indispensable in the field of cardiac electrophysiology for studying depolarization wave propagation, estimating the conduction velocity of electrical impulses, and measuring Ca2+ dynamics in cardiac cells and tissues. In addition, mapping these electrophysiological parameters is important for understanding cardiac arrhythmia mechanisms. In this review, we delve into the fundamentals of cardiac optical mapping technology and its applications when applied to hiPSC-derived cardiomyocytes and discuss related advantages and challenges. We also provide a detailed description of the processing and analysis of optical mapping data, which is a crucial step in the study of cardiac diseases and arrhythmia mechanisms for extracting and comparing relevant electrophysiological parameters.
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Affiliation(s)
- Mohammed Djemai
- CERVO Brain Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
| | - Michael Cupelli
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY 11209, USA
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY 11203, USA
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY 11209, USA
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY 11203, USA
- Department of Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Mohamed Chahine
- CERVO Brain Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
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Kovalenko SG, Frolova SR, Kramkova VK, Berezovskii AK, Popov MA, Shumakov DV, Zybin DI, Agafonov EG, Dontsov VV, Agladze KI. Development of a Method for Isolation of Mature Cardiomyocytes from Human Heart Biopsy Specimens. Bull Exp Biol Med 2023; 175:585-591. [PMID: 37768452 DOI: 10.1007/s10517-023-05907-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Indexed: 09/29/2023]
Abstract
To increase the yield of living cells and their survival, studies were carried out to optimize the method for isolating cardiomyocytes from biopsy specimens excised from the right atrial appendages. It was found that creatine, blebbistatin, and taurine are necessary components of the buffer solution during cardiomyocyte isolation, and that composition of the solutions is a more important factor than their oxygenation.
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Affiliation(s)
- S G Kovalenko
- Research Laboratory of Molecular and Cellular Diagnostics, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
- Laboratory of Experimental and Cellular Medicine, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region, Russia
| | - Sh R Frolova
- Research Laboratory of Molecular and Cellular Diagnostics, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
- Laboratory of Experimental and Cellular Medicine, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region, Russia
| | - V K Kramkova
- Laboratory of Experimental and Cellular Medicine, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region, Russia
| | - A K Berezovskii
- Laboratory of Experimental and Cellular Medicine, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region, Russia
| | - M A Popov
- Department of Heart and Vessels Surgery, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
| | - D V Shumakov
- Department of Heart and Vessels Surgery, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
| | - D I Zybin
- Department of Heart and Vessels Surgery, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
| | - E G Agafonov
- Department of Heart and Vessels Surgery, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
| | - V V Dontsov
- Department of Heart and Vessels Surgery, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia
| | - K I Agladze
- Research Laboratory of Molecular and Cellular Diagnostics, M. F. Vladimirsky Moscow Region Research Clinical Institute, Moscow, Russia.
- Laboratory of Experimental and Cellular Medicine, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region, Russia.
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15
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Haq KT, Roberts A, Berk F, Allen S, Swift LM, Posnack NG. KairoSight-3.0 : A Validated Optical Mapping Software to Characterize Cardiac Electrophysiology, Excitation-Contraction Coupling, and Alternans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.01.538926. [PMID: 37205349 PMCID: PMC10187248 DOI: 10.1101/2023.05.01.538926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Background Cardiac optical mapping is an imaging technique that measures fluorescent signals across a cardiac preparation. Dual optical mapping of voltage-sensitive and calcium-sensitive probes allow for simultaneous recordings of cardiac action potentials and intracellular calcium transients with high spatiotemporal resolution. The analysis of these complex optical datasets is both time intensive and technically challenging; as such, we have developed a software package for semi-automated image processing and analysis. Herein, we report an updated version of our software package ( KairoSight-3 . 0 ) with features to enhance characterization of cardiac parameters using optical signals. Methods To test software validity and applicability, we used Langendorff-perfused heart preparations to record transmembrane voltage and intracellular calcium signals from the epicardial surface. Isolated hearts from guinea pigs and rats were loaded with a potentiometric dye (RH237) and/or calcium indicator dye (Rhod-2AM) and fluorescent signals were acquired. We used Python 3.8.5 programming language to develop the KairoSight-3 . 0 software. Cardiac maps were validated with a user-specified manual mapping approach. Results Manual maps of action potential duration (30 or 80% repolarization), calcium transient duration (30 or 80% reuptake), action potential and calcium transient alternans were constituted to validate the accuracy of software-generated maps. Manual and software maps had high accuracy, with >97% of manual and software values falling within 10 ms of each other and >75% within 5 ms for action potential duration and calcium transient duration measurements (n=1000-2000 pixels). Further, our software package includes additional cardiac metric measurement tools to analyze signal-to-noise ratio, conduction velocity, action potential and calcium transient alternans, and action potential-calcium transient coupling time to produce physiologically meaningful optical maps. Conclusions KairoSight-3 . 0 has enhanced capabilities to perform measurements of cardiac electrophysiology, calcium handling, and the excitation-contraction coupling with satisfactory accuracy. Graphical Abstract Demonstrating Experimental and Data Analysis Workflow Created with Biorender.com.
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16
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Kappadan V, Sohi A, Parlitz U, Luther S, Uzelac I, Fenton F, Peters NS, Christoph J, Ng FS. Optical mapping of contracting hearts. J Physiol 2023; 601:1353-1370. [PMID: 36866700 PMCID: PMC10952556 DOI: 10.1113/jp283683] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Optical mapping is a widely used tool to record and visualize the electrophysiological properties in a variety of myocardial preparations such as Langendorff-perfused isolated hearts, coronary-perfused wedge preparations, and cell culture monolayers. Motion artifact originating from the mechanical contraction of the myocardium creates a significant challenge to performing optical mapping of contracting hearts. Hence, to minimize the motion artifact, cardiac optical mapping studies are mostly performed on non-contracting hearts, where the mechanical contraction is removed using pharmacological excitation-contraction uncouplers. However, such experimental preparations eliminate the possibility of electromechanical interaction, and effects such as mechano-electric feedback cannot be studied. Recent developments in computer vision algorithms and ratiometric techniques have opened the possibility of performing optical mapping studies on isolated contracting hearts. In this review, we discuss the existing techniques and challenges of optical mapping of contracting hearts.
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Affiliation(s)
- Vineesh Kappadan
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Anies Sohi
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Ulrich Parlitz
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Stefan Luther
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Ilija Uzelac
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Flavio Fenton
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Nicholas S Peters
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Jan Christoph
- Cardiovascular Research InstituteUniversity of CaliforniaSan FranciscoCAUSA
| | - Fu Siong Ng
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
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17
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Mattison L, Verma A, Tarakji KG, Reichlin T, Hindricks G, Sack KL, Önal B, Schmidt MM, Miklavčič D, Sigg DC. Effect of contact force on pulsed field ablation lesions in porcine cardiac tissue. J Cardiovasc Electrophysiol 2023; 34:693-699. [PMID: 36640426 DOI: 10.1111/jce.15813] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/13/2022] [Accepted: 12/26/2022] [Indexed: 01/15/2023]
Abstract
INTRODUCTION Contact force has been used to titrate lesion formation for radiofrequency ablation. Pulsed field ablation (PFA) is a field-based ablation technology for which limited evidence on the impact of contact force on lesion size is available. METHODS Porcine hearts (n = 6) were perfused using a modified Langendorff set-up. A prototype focal PFA catheter attached to a force gauge was held perpendicular to the epicardium and lowered until contact was made. Contact force was recorded during each PFA delivery. Matured lesions were cross-sectioned, stained, and the lesion dimensions measured. RESULTS A total of 82 lesions were evaluated with contact forces between 1.3 and 48.6 g. Mean lesion depth was 4.8 ± 0.9 mm (standard deviation), mean lesion width was 9.1 ± 1.3 mm, and mean lesion volume was 217.0 ± 96.6 mm3 . Linear regression curves showed an increase of only 0.01 mm in depth (depth = 0.01 × contact force + 4.41, R2 = 0.05), 0.03 mm in width (width = 0.03 × contact force + 8.26, R2 = 0.13) for each additional gram of contact force, and 2.20 mm3 in volume (volume = 2.20 × contact force + 162, R2 = 0.10). CONCLUSION Increasing contact force using a bipolar, biphasic focal PFA system has minimal effects on acute lesion dimensions in an isolated porcine heart model and achieving tissue contact is more important than the force with which that contact is made.
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Affiliation(s)
| | - Atul Verma
- McGill University Health Center, McGill University, Montreal, Quebec, Canada
| | | | - Tobias Reichlin
- Department of Cardiology, Inselspital-University Hospital Bern, University of Bern, Bern, Switzerland
| | - Gerhard Hindricks
- Department of Electrophysiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | | | | | | | - Damijan Miklavčič
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
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18
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Caldwell JL, Lee IJ, Ngo L, Wang L, Bahriz S, Xu B, Bers DM, Navedo MF, Bossuyt J, Xiang YK, Ripplinger CM. Whole-heart multiparametric optical imaging reveals sex-dependent heterogeneity in cAMP signaling and repolarization kinetics. SCIENCE ADVANCES 2023; 9:eadd5799. [PMID: 36662864 PMCID: PMC9858506 DOI: 10.1126/sciadv.add5799] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
Cyclic adenosine 3',5'-monophosphate (cAMP) is a key second messenger in cardiomyocytes responsible for transducing autonomic signals into downstream electrophysiological responses. Previous studies have shown intracellular heterogeneity and compartmentalization of cAMP signaling. However, whether cAMP signaling occurs heterogeneously throughout the intact heart and how this drives sex-dependent functional responses are unknown. Here, we developed and validated a novel cardiac-specific fluorescence resonance energy transfer-based cAMP reporter mouse and a combined voltage-cAMP whole-heart imaging system. We showed that in male hearts, cAMP was uniformly activated in response to pharmacological β-adrenergic stimulation. In contrast, female hearts showed that cAMP levels decayed faster in apical versus basal regions, which was associated with nonuniform action potential changes and notable changes in the direction of repolarization. Apical phosphodiesterase (PDE) activity was higher in female versus male hearts, and PDE inhibition prevented repolarization changes in female hearts. Thus, our imaging approach revealed sex-dependent regional breakdown of cAMP and associated electrophysiological differences.
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Affiliation(s)
| | - I-Ju Lee
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Lena Ngo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Sherif Bahriz
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Bing Xu
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- VA Northern California, Mather, CA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Yang K. Xiang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- VA Northern California, Mather, CA, USA
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19
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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20
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Lindsey ML. Getting it Right. Am J Physiol Heart Circ Physiol 2022; 323:H421-H423. [PMID: 35930444 DOI: 10.1152/ajpheart.00400.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Merry L Lindsey
- School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, United States
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Nayir S, Lacour SP, Kucera JP. Active force generation contributes to the complexity of spontaneous activity and to the response to stretch of murine cardiomyocyte cultures. J Physiol 2022; 600:3287-3312. [PMID: 35679256 PMCID: PMC9541716 DOI: 10.1113/jp283083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/01/2022] [Indexed: 11/17/2022] Open
Abstract
Abstract Cardiomyocyte cultures exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. In such preparations, beat rate variability exhibits features similar to those of heart rate variability in vivo. Mechanical deformations and forces feed back on the electrical properties of cardiomyocytes, but it is not fully elucidated how this mechano‐electrical interplay affects beating variability in such preparations. Using stretchable microelectrode arrays, we assessed the effects of the myosin inhibitor blebbistatin and the non‐selective stretch‐activated channel blocker streptomycin on beating variability and on the response of neonatal or fetal murine ventricular cell cultures against deformation. Spontaneous electrical activity was recorded without stretch and upon predefined deformation protocols (5% uniaxial and 2% equibiaxial strain, applied repeatedly for 1 min every 3 min). Without stretch, spontaneous activity originated from the edge of the preparations, and its site of origin switched frequently in a complex manner across the cultures. Blebbistatin did not change mean beat rate, but it decreased the spatial complexity of spontaneous activity. In contrast, streptomycin did not exert any manifest effects. During the deformation protocols, beat rate increased transiently upon stretch but, paradoxically, also upon release. Blebbistatin attenuated the response to stretch, whereas this response was not affected by streptomycin. Therefore, our data support the notion that in a spontaneously firing network of cardiomyocytes, active force generation, rather than stretch‐activated channels, is involved mechanistically in the complexity of the spatiotemporal patterns of spontaneous activity and in the stretch‐induced acceleration of beating.
![]() Key points Monolayer cultures of cardiac cells exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. Beating variability in these preparations recapitulates the power‐law behaviour of heart rate variability in vivo. However, the effects of mechano‐electrical feedback on beating variability are not yet fully understood. Using stretchable microelectrode arrays, we examined the effects of the contraction uncoupler blebbistatin and the non‐specific stretch‐activated channel blocker streptomycin on beating variability and on stretch‐induced changes of beat rate. Without stretch, blebbistatin decreased the spatial complexity of beating variability, whereas streptomycin had no effects. Both stretch and release increased beat rate transiently; blebbistatin attenuated the increase of beat rate upon stretch, whereas streptomycin had no effects. Active force generation contributes to the complexity of spatiotemporal patterns of beating variability and to the increase of beat rate upon mechanical deformation. Our study contributes to the understanding of how mechano‐electrical feedback influences heart rate variability.
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Affiliation(s)
- Seyma Nayir
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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Lebert J, Ravi N, Kensah G, Christoph J. Real-Time Optical Mapping of Contracting Cardiac Tissues With GPU-Accelerated Numerical Motion Tracking. Front Cardiovasc Med 2022; 9:787627. [PMID: 35686036 PMCID: PMC9172765 DOI: 10.3389/fcvm.2022.787627] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/12/2022] [Indexed: 11/15/2022] Open
Abstract
Optical mapping of action potentials or calcium transients in contracting cardiac tissues are challenging because of the severe sensitivity of the measurements to motion. The measurements rely on the accurate numerical tracking and analysis of fluorescence changes emitted by the tissue as it moves, and inaccurate or no tracking can produce motion artifacts and lead to imprecise measurements that can prohibit the analysis of the data. Recently, it was demonstrated that numerical motion-tracking and -stabilization can effectively inhibit motion artifacts, allowing highly detailed simultaneous measurements of electrophysiological phenomena and tissue mechanics. However, the field of electromechanical optical mapping is still young and under development. To date, the technique is only used by a few laboratories, the processing of the video data is time-consuming and performed offline post-acquisition as it is associated with a considerable demand for computing power. In addition, a systematic review of numerical motion tracking algorithms applicable to optical mapping data is lacking. To address these issues, we evaluated 5 open-source numerical motion-tracking algorithms implemented on a graphics processing unit (GPU) and compared their performance when tracking and compensating motion and measuring optical traces in voltage- or calcium-sensitive optical mapping videos of contracting cardiac tissues. Using GPU-accelerated numerical motion tracking, the processing times necessary to analyze optical mapping videos become substantially reduced. We demonstrate that it is possible to track and stabilize motion and create motion-compensated optical maps in real-time with low-resolution (128 x 128 pixels) and high resolution (800 x 800 pixels) optical mapping videos acquired at 500 and 40 fps, respectively. We evaluated the tracking accuracies and motion-stabilization capabilities of the GPU-based algorithms on synthetic optical mapping videos, determined their sensitivity to fluorescence signals and noise, and demonstrate the efficacy of the Farnebäck algorithm with recordings of contracting human cardiac cell cultures and beating hearts from 3 different species (mouse, rabbit, pig) imaged with 4 different high-speed cameras. GPU-accelerated processing provides a substantial increase in processing speed, which could open the path for more widespread use of numerical motion tracking and stabilization algorithms during routine optical mapping studies.
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Affiliation(s)
- Jan Lebert
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
| | - Namita Ravi
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- Yale School of Medicine, Yale University, New Haven, CT, United States
| | - George Kensah
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
- Department for Cardiothoracic and Vascular Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Christoph
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
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Stoyek MR, MacDonald EA, Mantifel M, Baillie JS, Selig BM, Croll RP, Smith FM, Quinn TA. Drivers of Sinoatrial Node Automaticity in Zebrafish: Comparison With Mechanisms of Mammalian Pacemaker Function. Front Physiol 2022; 13:818122. [PMID: 35295582 PMCID: PMC8919049 DOI: 10.3389/fphys.2022.818122] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/21/2022] [Indexed: 12/13/2022] Open
Abstract
Cardiac excitation originates in the sinoatrial node (SAN), due to the automaticity of this distinct region of the heart. SAN automaticity is the result of a gradual depolarisation of the membrane potential in diastole, driven by a coupled system of transarcolemmal ion currents and intracellular Ca2+ cycling. The frequency of SAN excitation determines heart rate and is under the control of extra- and intracardiac (extrinsic and intrinsic) factors, including neural inputs and responses to tissue stretch. While the structure, function, and control of the SAN have been extensively studied in mammals, and some critical aspects have been shown to be similar in zebrafish, the specific drivers of zebrafish SAN automaticity and the response of its excitation to vagal nerve stimulation and mechanical preload remain incompletely understood. As the zebrafish represents an important alternative experimental model for the study of cardiac (patho-) physiology, we sought to determine its drivers of SAN automaticity and the response to nerve stimulation and baseline stretch. Using a pharmacological approach mirroring classic mammalian experiments, along with electrical stimulation of intact cardiac vagal nerves and the application of mechanical preload to the SAN, we demonstrate that the principal components of the coupled membrane- Ca2+ pacemaker system that drives automaticity in mammals are also active in the zebrafish, and that the effects of extra- and intracardiac control of heart rate seen in mammals are also present. Overall, these results, combined with previously published work, support the utility of the zebrafish as a novel experimental model for studies of SAN (patho-) physiological function.
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Affiliation(s)
- Matthew R. Stoyek
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Eilidh A. MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Melissa Mantifel
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Jonathan S. Baillie
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Bailey M. Selig
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Roger P. Croll
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Frank M. Smith
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
- *Correspondence: T. Alexander Quinn,
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