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Nyman M, Stølen TO, Johnsen AB, Garten K, Burton FL, Smith GL, Loennechen JP. A comprehensive protocol combining in vivo and ex vivo electrophysiological experiments in an arrhythmogenic animal model. Am J Physiol Heart Circ Physiol 2024; 326:H203-H215. [PMID: 37975708 PMCID: PMC11213483 DOI: 10.1152/ajpheart.00358.2023] [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: 06/20/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Ventricular arrhythmias contribute significantly to cardiovascular mortality, with coronary artery disease as the predominant underlying cause. Understanding the mechanisms of arrhythmogenesis is essential to identify proarrhythmic factors and develop novel approaches for antiarrhythmic prophylaxis and treatment. Animal models are vital in basic research on cardiac arrhythmias, encompassing molecular, cellular, ex vivo whole heart, and in vivo models. Most studies use either in vivo protocols lacking important information on clinical relevance or exclusively ex vivo protocols, thereby missing the opportunity to explore underlying mechanisms. Consequently, interpretation may be difficult due to dissimilarities in animal models, interventions, and individual properties across animals. Moreover, proarrhythmic effects observed in vivo are often not replicated in corresponding ex vivo preparations during mechanistic studies. We have established a protocol to perform both an in vivo and ex vivo electrophysiological characterization in an arrhythmogenic rat model with heart failure following myocardial infarction. The same animal is followed throughout the experiment. In vivo methods involve intracardiac programmed electrical stimulation and external defibrillation to terminate sustained ventricular arrhythmia. Ex vivo methods conducted on the Langendorff-perfused heart include an electrophysiological study with optical mapping of regional action potentials, conduction velocities, and dispersion of electrophysiological properties. By exploring the retention of the in vivo proarrhythmic phenotype ex vivo, we aim to examine whether the subsequent ex vivo detailed measurements are relevant to in vivo pathological behavior. This protocol can enhance greater understanding of cardiac arrhythmias by providing a standardized, yet adaptable model for evaluating arrhythmogenicity or antiarrhythmic interventions in cardiac diseases.NEW & NOTEWORTHY Rodent models are widely used in arrhythmia research. However, most studies do not standardize clinically relevant in vivo and ex vivo techniques to support their conclusions. Here, we present a comprehensive electrophysiological protocol in an arrhythmogenic rat model, connecting in vivo and ex vivo programmed electrical stimulation with optical mapping. By establishing this protocol, we aim to facilitate the adoption of a standardized model for investigating arrhythmias, enhancing research rigor and comparability in this field.
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Affiliation(s)
- Mathias Nyman
- Department of Circulation and Medical Imaging, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
- Clinic of Cardiology, St. Olavs University Hospital, Trondheim, Norway
| | - Tomas O Stølen
- Department of Circulation and Medical Imaging, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Anne Berit Johnsen
- Department of Circulation and Medical Imaging, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Karin Garten
- Department of Circulation and Medical Imaging, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Francis L Burton
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, United Kingdom
| | - Godfrey L Smith
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, United Kingdom
| | - Jan Pål Loennechen
- Department of Circulation and Medical Imaging, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
- Clinic of Cardiology, St. Olavs University Hospital, Trondheim, Norway
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Blackwell DJ, Schmeckpeper J, Knollmann BC. Animal Models to Study Cardiac Arrhythmias. Circ Res 2022; 130:1926-1964. [PMID: 35679367 DOI: 10.1161/circresaha.122.320258] [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: 11/16/2022]
Abstract
Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.
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Affiliation(s)
- Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Jeffrey Schmeckpeper
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
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Ji X, Bradley JL, Zheng G, Ge W, Xu J, Hu J, He F, Shabnam R, Peberdy MA, Ornato JP, Chen Q, Lesnefsky EJ, Tang W. Cerebral and myocardial mitochondrial injury differ in a rat model of cardiac arrest and cardiopulmonary resuscitation. Biomed Pharmacother 2021; 140:111743. [PMID: 34020243 DOI: 10.1016/j.biopha.2021.111743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 11/18/2022] Open
Abstract
Brain mitochondria are more sensitive to global ischemia compared to heart mitochondria. Complex I in the electron transport chain (ETC) is sensitive to ischemic injury and is a major control point of the rate of ADP stimulated oxygen consumption. The purpose of this study was to explore whether changes in cerebral and myocardial mitochondria differ after cardiac arrest. Animals were randomized into 4 groups (n = 6): 1) Sham 2) VF 3) VF+CPR 4) ROSC 1hr. Ventricular Fibrillation (VF) was induced through a guide wire advanced from the right jugular vein into the ventricle and untreated for 8 min. Resuscitation was attempted with a 4J defibrillation after 8 min of cardiopulmonary resuscitation (CPR). Brain mitochondria and cardiac mitochondrial subpopulations were isolated. Calcium retention capacity was measured to assess susceptibility to mitochondrial permeability transition pore opening. ADP stimulated oxygen consumption and ETC activity assays were performed. Brain mitochondria are far more sensitive to injury during cardiac arrest and resuscitation compared to cardiac mitochondria. Complex I is highly sensitive to injury in brain mitochondria. With markedly decreased calcium retention capacity, mitochondria contribute to cerebral reperfusion injury. Therapeutic preservation of cerebral mitochondrial activity and mitochondrial function during cardiac arrest may improve post-resuscitation neurologic function.
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Affiliation(s)
- Xianfei Ji
- Department of Emergency, Shandong Provincial Hospital affiliated to Shandong First Medical University, Jinan, China; Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | - Jennifer L Bradley
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA.
| | - Guanghui Zheng
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | - Weiwei Ge
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | - Jing Xu
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | - Juntao Hu
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | - Fenglian He
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA.
| | | | - Mary Ann Peberdy
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA; Departments of Internal Medicine and Emergency Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA; Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA.
| | - Joseph P Ornato
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA; Department of Emergency Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA.
| | - Qun Chen
- Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA.
| | - Edward J Lesnefsky
- Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA; Medical Service, McGuire Department of Veterans Affairs Medical Center, Richmond, VA, USA; McGuire Research Institute, Richmond, VA, USA.
| | - Wanchun Tang
- Weil Institute of Emergency and Critical Care Research, Virginia Commonwealth University, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA; Department of Emergency Medicine, Virginia Commonwealth University Health System, Richmond, VA, USA.
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Pille JA, Riess ML. Potential Effects of Poloxamer 188 on Rat Isolated Brain Mitochondria after Oxidative Stress In Vivo and In Vitro. Brain Sci 2021; 11:brainsci11010122. [PMID: 33477541 PMCID: PMC7831103 DOI: 10.3390/brainsci11010122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 12/26/2022] Open
Abstract
Outcome after cerebral ischemia is often dismal. Reperfusion adds significantly to the ischemic injury itself. Therefore, new strategies targeting ischemia/reperfusion (I/R) injury are critically needed. Poloxamer (P)188, an amphiphilic triblock copolymer, is a highly promising pharmacological therapeutic as its capability to insert into injured cell membranes has been reported to protect against I/R injury in various models. Although mitochondrial function particularly profits from P188 treatment after I/R, it remains unclear if this beneficial effect occurs directly or indirectly. Here, rat isolated brain mitochondria underwent oxidative stress in vivo by asphyxial cardiac arrest or in vitro by the addition of hydrogen peroxide (H2O2) after isolation. Mitochondrial function was assessed by adenosine triphosphate synthesis, oxygen consumption, and calcium retention capacity. Both asphyxia and H2O2 exposure significantly impaired mitochondrial function. P188 did not preserve mitochondrial function after either injury mechanism. Further research is indicated.
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Affiliation(s)
- Johannes A Pille
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
- Department of Anesthesiology, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Matthias L Riess
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Anesthesiology, TVHS VA Medical Center, Nashville, TN 37212, USA
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Wang CH, Chang WT, Tsai MS, Huang CH, Chen WJ. Synergistic Effects of Moderate Therapeutic Hypothermia and Levosimendan on Cardiac Function and Survival After Asphyxia-Induced Cardiac Arrest in Rats. J Am Heart Assoc 2020; 9:e016139. [PMID: 32476598 PMCID: PMC7429058 DOI: 10.1161/jaha.120.016139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background This study investigated whether levosimendan, an inotropic calcium sensitizer, when combined with moderate therapeutic hypothermia, may exert synergistic benefits on post–cardiac arrest myocardial dysfunction and improve outcomes. Methods and Results After 9.5‐minute asphyxia‐induced cardiac arrest and resuscitation, 48 rats were randomized equally into 4 groups following return of spontaneous circulation (ROSC), including normothermia, hypothermia, normothermia–levosimendan, and hypothermia–levosimendan groups. For the normothermia group, the target temperature was 37°C while for the hypothermia group, the target temperature was 32°C, both of which were to be maintained for 4 hours after ROSC. Levosimendan was administered after ROSC with a loading dose of 10 μg/kg and then infused at 0.1 μg/kg per min for 4 hours. In the hypothermia–levosimendan group, left ventricular systolic function and cardiac output increased significantly, whereas the heart rate and systemic vascular resistance decreased significantly compared with the normothermia group. Also, the concentrations of interleukin 1β at 4 hours post‐ROSC and the production of NO between 1 hour and 4 hours post‐ROSC were reduced significantly in the hypothermia–levosimendan group compared with the normothermia group. The 72‐hour post‐ROSC survival and neurological recovery were also significantly better in the hypothermia–levosimendan group compared with the normothermia group (survival, 100% versus 50%, χ2 test, P=0.006). Conclusions Compared with normothermia, only combined moderate therapeutic hypothermia and levosimendan treatment could consistently improve post–cardiac arrest myocardial dysfunction and decrease the release of pro‐inflammatory molecules, thereby improving survival and neurological outcomes. These findings suggest synergistic benefits between moderate therapeutic hypothermia and levosimendan.
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Affiliation(s)
- Chih-Hung Wang
- Department of Emergency Medicine National Taiwan University Hospital Taipei Taiwan.,Department of Emergency Medicine College of Medicine National Taiwan University Taipei Taiwan
| | - Wei-Tien Chang
- Department of Emergency Medicine National Taiwan University Hospital Taipei Taiwan.,Department of Emergency Medicine College of Medicine National Taiwan University Taipei Taiwan
| | - Min-Shan Tsai
- Department of Emergency Medicine National Taiwan University Hospital Taipei Taiwan.,Department of Emergency Medicine College of Medicine National Taiwan University Taipei Taiwan
| | - Chien-Hua Huang
- Department of Emergency Medicine National Taiwan University Hospital Taipei Taiwan.,Department of Emergency Medicine College of Medicine National Taiwan University Taipei Taiwan
| | - Wen-Jone Chen
- Department of Emergency Medicine National Taiwan University Hospital Taipei Taiwan.,Department of Emergency Medicine College of Medicine National Taiwan University Taipei Taiwan.,Division of Cardiology Department of Internal Medicine National Taiwan University Hospital and National Taiwan University College of Medicine Taipei Taiwan
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Balzer C, Cleveland WJ, Jinka TR, Riess ML. Video laryngoscopic oral intubation in rats: a simple and effective method. Am J Physiol Lung Cell Mol Physiol 2020; 318:L1032-L1035. [PMID: 32233786 DOI: 10.1152/ajplung.00498.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endotracheal intubation is a vital component of many rat in vivo experiments to secure the airway and allow controlled ventilation. Even in the hands of experienced researchers, however, the procedure remains technically challenging. The safest and most reliable way for human intubation is by video laryngoscopy. Previous attempts to apply this technique in rodents have been complicated and expensive. We, hereby, describe a novel, noninvasive method to safely intubate rats orally by video laryngoscopy, thus avoiding the need for a surgical tracheostomy. By repurposing a commercially available ear wax removal device, visualization of the rat larynx can be significantly enhanced. Because of its small diameter, integrated illumination, and a powerful camera with adequate focal length, the device has all of the necessary properties for exploring the upper airway of a rat. After identifying the vocal cords by video laryngoscopy, the insertion of an endotracheal tube (a 14G intravenous catheter) into the trachea under constant visual control is facilitated by using PE50 polyethylene tubing as a stylet (Seldinger technique). The procedure has been performed more than 60 times in our laboratory; all intubations were successful on the first attempt, and no adverse events were observed. We conclude that the described procedure is a simple and effective way to intubate a rat noninvasively, using inexpensive and commercially available equipment.
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Affiliation(s)
- Claudius Balzer
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - William J Cleveland
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Tulasi R Jinka
- Department of Emergency Medicine, University of Michigan Medical School, Ann Arbor, Michigan.,Michigan Center for Integrative Research in Critical Care, University of Michigan, Ann Arbor, Michigan
| | - Matthias L Riess
- Department of Anesthesiology, Tennessee Valley Healthcare System Veterans Affairs Medical Center, Vanderbilt University, Nashville, Tennessee.,Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
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Ayoub IM, Radhakrishnan J, Gazmuri RJ. In vivo opening of the mitochondrial permeability transition pore in a rat model of ventricular fibrillation and closed-chest resuscitation. Am J Transl Res 2017; 9:3345-3359. [PMID: 28804552 PMCID: PMC5553884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/11/2016] [Indexed: 06/07/2023]
Abstract
Opening of the mitochondrial permeability transition pore (mPTP) is considered central to reperfusion injury. Yet, most of our knowledge comes from observations in isolated mitochondria, cells, and organs. We used a rat model of ventricular fibrillation (VF) and closed-chest resuscitation to examine whether the mPTP opens in vivo and whether cyclosporine A (CsA) attenuates the associated myocardial injury. Two series of 26 and 18 rats each underwent 10 minutes of untreated VF before attempting resuscitation. In series-1, rats received 50 µCi of tritium-labeled 2-deoxyglucose ([3H]DOG) harvesting their hearts at baseline (n=5), during VF (n=5), during resuscitation (n=6), and at post-resuscitation 60 minutes (n=5) and 240 minutes (n=5). mPTP opening was estimated measuring the ratio of mitochondria to left ventricular intracellular [3H]. In series-2, rats received 10 mg/kg of CsA or vehicle before resuscitation, measuring mitochondrial NAD+ content to indirectly assess mPTP opening. In Series-1, the mPTP opening ratio vs baseline (10.4 ± 1.9) increased during VF (16.8 ± 2.4, NS), closed-chest resuscitation (20.8 ± 6.3, P<0.05), and at post-resuscitation 60 minutes (20.9 ± 4.7, P<0.05) and 240 minutes (25.7 ± 11.0, P<0.01). In series 2, CsA failed to attenuate reductions in mitochondrial NAD+ and did not affect plasma cytochrome c, plasma cardiac troponin I, myocardial function, and survival. We report for the first time in an intact rat model of VF that mPTP opens during closed-chest resuscitation consistent with previous observations in mitochondria, cells, and organs of mPTP opening upon reperfusion. CsA, at the dose of 10 mg/kg neither prevented mPTP opening nor attenuated post-resuscitation myocardial injury.
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Affiliation(s)
- Iyad M Ayoub
- Resuscitation Institute at Rosalind Franklin University of Medicine and ScienceNorth Chicago, Illinois, USA
| | - Jeejabai Radhakrishnan
- Resuscitation Institute at Rosalind Franklin University of Medicine and ScienceNorth Chicago, Illinois, USA
| | - Raúl J Gazmuri
- Resuscitation Institute at Rosalind Franklin University of Medicine and ScienceNorth Chicago, Illinois, USA
- Critical Care Medicine, Captain James A Lovell Federal Health Care CenterNorth Chicago, Illinois, USA
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