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Cavallero S, Roustaei M, Satta S, Cho JM, Phan H, Baek KI, Blázquez-Medela AM, Gonzalez-Ramos S, Vu K, Park SK, Yokota T, Sumner J, Mack JJ, Sigmund CD, Reddy ST, Li R, Hsiai TK. Exercise mitigates flow recirculation and activates metabolic transducer SCD1 to catalyze vascular protective metabolites. SCIENCE ADVANCES 2024; 10:eadj7481. [PMID: 38354249 PMCID: PMC10866565 DOI: 10.1126/sciadv.adj7481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 01/11/2024] [Indexed: 02/16/2024]
Abstract
Exercise promotes pulsatile shear stress in the arterial circulation and ameliorates cardiometabolic diseases. However, exercise-mediated metabolic transducers for vascular protection remain under-investigated. Untargeted metabolomic analysis demonstrated that wild-type mice undergoing voluntary wheel running exercise expressed increased endothelial stearoyl-CoA desaturase 1 (SCD1) that catalyzes anti-inflammatory lipid metabolites, namely, oleic (OA) and palmitoleic acids (PA), to mitigate NF-κB-mediated inflammatory responses. In silico analysis revealed that exercise augmented time-averaged wall shear stress but mitigated flow recirculation and oscillatory shear index in the lesser curvature of the mouse aortic arch. Following exercise, endothelial Scd1-deleted mice (Ldlr-/- Scd1EC-/-) on high-fat diet developed persistent VCAM1-positive endothelium in the lesser curvature and the descending aorta, whereas SCD1 overexpression via adenovirus transfection mitigated endoplasmic reticulum stress and inflammatory biomarkers. Single-cell transcriptomics of the aorta identified Scd1-positive and Vcam1-negative endothelial subclusters interacting with other candidate genes. Thus, exercise mitigates flow recirculation and activates endothelial SCD1 to catalyze OA and PA for vascular endothelial protection.
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Affiliation(s)
- Susana Cavallero
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Mehrdad Roustaei
- Department of Bioengineering, School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Sandro Satta
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Jae Min Cho
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Henry Phan
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Kyung In Baek
- Department of Bioengineering, School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Ana M. Blázquez-Medela
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Sheila Gonzalez-Ramos
- Department of Bioengineering, School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Khoa Vu
- Department of Bioengineering, School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Seul-Ki Park
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Tomohiro Yokota
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Jennifer Sumner
- Department of Psychology, College of Life Sciences, University of California, Los Angeles, CA, USA
| | - Julia J. Mack
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Curt D. Sigmund
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Srinivasa T. Reddy
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Rongsong Li
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - Tzung K. Hsiai
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Medicine, VA Greater Los Angeles Health Care System, Los Angeles, CA, USA
- Department of Bioengineering, School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
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2
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Calvet C, Seebeck P. What to consider for ECG in mice-with special emphasis on telemetry. Mamm Genome 2023; 34:166-179. [PMID: 36749381 PMCID: PMC10290603 DOI: 10.1007/s00335-023-09977-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 01/16/2023] [Indexed: 02/08/2023]
Abstract
Genetically or surgically altered mice are commonly used as models of human cardiovascular diseases. Electrocardiography (ECG) is the gold standard to assess cardiac electrophysiology as well as to identify cardiac phenotypes and responses to pharmacological and surgical interventions. A variety of methods are used for mouse ECG acquisition under diverse conditions, making it difficult to compare different results. Non-invasive techniques allow only short-term data acquisition and are prone to stress or anesthesia related changes in cardiac activity. Telemetry offers continuous long-term acquisition of ECG data in conscious freely moving mice in their home cage environment. Additionally, it allows acquiring data 24/7 during different activities, can be combined with different challenges and most telemetry systems collect additional physiological parameters simultaneously. However, telemetry transmitters require surgical implantation, the equipment for data acquisition is relatively expensive and analysis of the vast number of ECG data is challenging and time-consuming. This review highlights the limits of non-invasive methods with respect to telemetry. In particular, primary screening using non-invasive methods can give a first hint; however, subtle cardiac phenotypes might be masked or compensated due to anesthesia and stress during these procedures. In addition, we detail the key differences between the mouse and human ECG. It is crucial to consider these differences when analyzing ECG data in order to properly translate the insights gained from murine models to human conditions.
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Affiliation(s)
- Charlotte Calvet
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
| | - Petra Seebeck
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
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3
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Cavallero S, Roustaei M, Satta S, Cho JM, Phan H, Baek KI, Blázquez-Medela AM, Gonzalez-Ramos S, Vu K, Park SK, Yokota T, Sumner JA, Mack JJ, Sigmund CD, Reddy ST, Li R, Hsiai TK. Exercise Mitigates Flow Recirculation and Activates Mechanosensitive Transcriptome to Uncover Endothelial SCD1-Catalyzed Anti-Inflammatory Metabolites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.02.539172. [PMID: 37205360 PMCID: PMC10187200 DOI: 10.1101/2023.05.02.539172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Exercise modulates vascular plasticity in multiple organ systems; however, the metabolomic transducers underlying exercise and vascular protection in the disturbed flow-prone vasculature remain under-investigated. We simulated exercise-augmented pulsatile shear stress (PSS) to mitigate flow recirculation in the lesser curvature of the aortic arch. When human aortic endothelial cells (HAECs) were subjected to PSS ( τ ave = 50 dyne·cm -2 , ∂τ/∂t = 71 dyne·cm -2 ·s -1 , 1 Hz), untargeted metabolomic analysis revealed that Stearoyl-CoA Desaturase (SCD1) in the endoplasmic reticulum (ER) catalyzed the fatty acid metabolite, oleic acid (OA), to mitigate inflammatory mediators. Following 24 hours of exercise, wild-type C57BL/6J mice developed elevated SCD1-catalyzed lipid metabolites in the plasma, including OA and palmitoleic acid (PA). Exercise over a 2-week period increased endothelial SCD1 in the ER. Exercise further modulated the time-averaged wall shear stress (TAWSS or τ ave) and oscillatory shear index (OSI ave ), upregulated Scd1 and attenuated VCAM1 expression in the disturbed flow-prone aortic arch in Ldlr -/- mice on high-fat diet but not in Ldlr -/- Scd1 EC-/- mice. Scd1 overexpression via recombinant adenovirus also mitigated ER stress. Single cell transcriptomic analysis of the mouse aorta revealed interconnection of Scd1 with mechanosensitive genes, namely Irs2 , Acox1 and Adipor2 that modulate lipid metabolism pathways. Taken together, exercise modulates PSS ( τ ave and OSI ave ) to activate SCD1 as a metabolomic transducer to ameliorate inflammation in the disturbed flow-prone vasculature.
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4
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Ivonin AG, Smirnova SL, Roshchevskaya IM. Body Surface Potential Mapping during Ventricular Depolarization in Rats after Acute Exhaustive Exercise. Arq Bras Cardiol 2022; 119:S0066-782X2022005014203. [PMID: 36102423 PMCID: PMC9750213 DOI: 10.36660/abc.20211058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 04/03/2022] [Accepted: 06/01/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Exhaustive physical exercise can cause substantial changes in the electrical properties of the myocardium. OBJECTIVE To evaluate, using body surface potential mapping, the electrical activity of the heart in rats during ventricular depolarization after acute exhaustive exercise. METHODS Twelve-week-old male rats were submitted to acute treadmill exercise at 36 m/min until exhaustion. Unipolar electrocardiograms (ECGs) from the torso surface were recorded in zoletil-anesthetized rats three to five days before (Pre-Ex), 5 and 10 minutes after exhaustive exercise (Post-Ex 5 and Post-Ex 10, respectively) simultaneously with ECGs in limb leads. The instantaneous body surface potential maps (BSPMs) were analyzed during ventricular depolarization. P values <0.05 were considered statistically significant. RESULTS Compared with Pre-Ex, an early completion of the second inversion of potential distributions, an early completion of ventricular depolarization, as well as a decrease in the duration of the middle phase and the total duration of ventricular depolarization on BSPMs were revealed at Post-Ex 5. Also, compared with Pre-Ex, an increase in the amplitude of negative BSPM extremum at the R-wave peak on the ECG in lead II (RII-peak) and a decrease in the amplitude of negative BSPM extremum at 3 and 4 ms after RII-peak were showed at Post-Ex 5. At Post-Ex 10, parameters of BSPMs did not differ from those at Pre-Ex. CONCLUSION In rats, acute exhaustive exercise causes reversible changes in the temporal and amplitude characteristics of BSPMs during ventricular depolarization, most likely related to alterations in the excitation of the main mass of the ventricular myocardium.
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Affiliation(s)
- Alexey G. Ivonin
- Department of Comparative CardiologyKomi Scientific Centre of the Ural BranchRussian Academy of SciencesSyktyvkarFederação Russa Department of Comparative Cardiology – Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences , Syktyvkar – Federação Russa
| | - Svetlana L. Smirnova
- Department of Comparative CardiologyKomi Scientific Centre of the Ural BranchRussian Academy of SciencesSyktyvkarFederação Russa Department of Comparative Cardiology – Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences , Syktyvkar – Federação Russa
| | - Irina M. Roshchevskaya
- Department of Comparative CardiologyKomi Scientific Centre of the Ural BranchRussian Academy of SciencesSyktyvkarFederação Russa Department of Comparative Cardiology – Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences , Syktyvkar – Federação Russa
- Laboratory of Pharmacological ScreeningResearch Zakusov Institute of PharmacologyMoscowFederação Russa Laboratory of Pharmacological Screening – Research Zakusov Institute of Pharmacology , Moscow – Federação Russa
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5
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Hastings MH, Herrera JJ, Guseh JS, Atlason B, Houstis NE, Abdul Kadir A, Li H, Sheffield C, Singh AP, Roh JD, Day SM, Rosenzweig A. Animal Models of Exercise From Rodents to Pythons. Circ Res 2022; 130:1994-2014. [PMID: 35679366 PMCID: PMC9202075 DOI: 10.1161/circresaha.122.320247] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Acute and chronic animal models of exercise are commonly used in research. Acute exercise testing is used, often in combination with genetic, pharmacological, or other manipulations, to study the impact of these manipulations on the cardiovascular response to exercise and to detect impairments or improvements in cardiovascular function that may not be evident at rest. Chronic exercise conditioning models are used to study the cardiac phenotypic response to regular exercise training and as a platform for discovery of novel pathways mediating cardiovascular benefits conferred by exercise conditioning that could be exploited therapeutically. The cardiovascular benefits of exercise are well established, and, frequently, molecular manipulations that mimic the pathway changes induced by exercise recapitulate at least some of its benefits. This review discusses approaches for assessing cardiovascular function during an acute exercise challenge in rodents, as well as practical and conceptual considerations in the use of common rodent exercise conditioning models. The case for studying feeding in the Burmese python as a model for exercise-like physiological adaptation is also explored.
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Affiliation(s)
- Margaret H Hastings
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Jonathan J Herrera
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor (J.J.H.)
| | - J Sawalla Guseh
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Bjarni Atlason
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Nicholas E Houstis
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Azrul Abdul Kadir
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Haobo Li
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Cedric Sheffield
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Anand P Singh
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Jason D Roh
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
| | - Sharlene M Day
- Cardiovascular Medicine, Perelman School of Medicine' University of Pennsylvania, Philadelphia (S.M.D.)
| | - Anthony Rosenzweig
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston (M.H.H., J.S.G., B.A., N.E.H., A.A.K., H.L., C.S., A.P.S., J.D.R., A.R.)
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6
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Lakin R, Debi R, Yang S, Polidovitch N, Goodman JM, Backx PH. Differential negative effects of acute exhaustive swim exercise on the right ventricle are associated with disproportionate hemodynamic loading. Am J Physiol Heart Circ Physiol 2021; 320:H1261-H1275. [PMID: 33416456 DOI: 10.1152/ajpheart.00603.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute exhaustive endurance exercise can differentially impact the right ventricle (RV) versus the left ventricle (LV). However, the hemodynamic basis for these differences and its impact on postexercise recovery remain unclear. Therefore, we assessed cardiac structure and function along with hemodynamic properties of mice subjected to single bouts (216 ± 8 min) of exhaustive swimming (ES). One-hour after ES, LVs displayed mild diastolic impairment compared with that in sedentary (SED) mice. Following dobutamine administration to assess functional reserve, diastolic and systolic function were slightly impaired. Twenty-four hours after ES, LV function was largely indistinguishable from that in SED. By contrast, 1-h post swim, RVs showed pronounced impairment of diastolic and systolic function with and without dobutamine, which persisted 24 h later. The degree of RV impairment correlated with the time-to-exhaustion. To identify hemodynamic factors mediating chamber-specific responses to ES, LV pressure was recorded during swimming. Swimming initiated immediate increases in heart rates (HRs), systolic pressure, dP/dtmax and -dP/dtmin, which remained stable for ∼45 min. LV end-diastolic pressures (LVEDP) increased to ≥45 mmHg during the first 10 min and subsequently declined. After 45 min, HR and -dP/dtmin declined, which correlated with gradual elevations in LVEDP (to ∼45 mmHg) as mice approached exhaustion. All parameters rapidly normalized postexercise. Consistent with human studies, our findings demonstrate a disproportionate negative impact of acute exhaustive exercise on RVs that persisted for at least 24 h. We speculate that the differential effects of exhaustive exercise on the ventricles arise from a ∼2-fold greater hemodynamic load in the RV than in LV originating from profound elevations in LVEDPs as mice approach exhaustion.NEW & NOTEWORTHY Acute exhaustive exercise differentially impacts the right ventricle (RV) versus left ventricle (LV), yet the underlying hemodynamic basis remains unclear. Using pressure-volume analyses and pressure-telemetry implantation in mice, we confirmed a marked disproportionate and persistent negative impact of exhaustive exercise on the RV. These differences in responses of the ventricles to exhaustive exercise are of clinical relevance, reflecting ∼2-fold greater hemodynamic RV loads versus LVs arising from massive (∼45 mmHg) increases in LV end-diastolic pressures at exhaustion.
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Affiliation(s)
- Robert Lakin
- Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada.,Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Ryan Debi
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Sibao Yang
- Department of Biology, York University, Toronto, Ontario, Canada.,Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Nazari Polidovitch
- Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Jack M Goodman
- Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
| | - Peter H Backx
- Department of Biology, York University, Toronto, Ontario, Canada.,Division of Cardiology, University Health Network, Toronto, Ontario, Canada
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7
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Species differences in cardiovascular physiology that affect pharmacology and toxicology. CURRENT OPINION IN TOXICOLOGY 2020. [DOI: 10.1016/j.cotox.2020.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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Lopez R, Marzban B, Gao X, Lauinger E, Van den Bergh F, Whitesall SE, Converso-Baran K, Burant CF, Michele DE, Beard DA. Impaired Myocardial Energetics Causes Mechanical Dysfunction in Decompensated Failing Hearts. FUNCTION 2020; 1:zqaa018. [PMID: 33074265 PMCID: PMC7552914 DOI: 10.1093/function/zqaa018] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/11/2020] [Accepted: 09/21/2020] [Indexed: 01/06/2023] Open
Abstract
Cardiac mechanical function is supported by ATP hydrolysis, which provides the chemical-free energy to drive the molecular processes underlying cardiac pumping. Physiological rates of myocardial ATP consumption require the heart to resynthesize its entire ATP pool several times per minute. In the failing heart, cardiomyocyte metabolic dysfunction leads to a reduction in the capacity for ATP synthesis and associated free energy to drive cellular processes. Yet it remains unclear if and how metabolic/energetic dysfunction that occurs during heart failure affects mechanical function of the heart. We hypothesize that changes in phosphate metabolite concentrations (ATP, ADP, inorganic phosphate) that are associated with decompensation and failure have direct roles in impeding contractile function of the myocardium in heart failure, contributing to the whole-body phenotype. To test this hypothesis, a transverse aortic constriction (TAC) rat model of pressure overload, hypertrophy, and decompensation was used to assess relationships between metrics of whole-organ pump function and myocardial energetic state. A multiscale computational model of cardiac mechanoenergetic coupling was used to identify and quantify the contribution of metabolic dysfunction to observed mechanical dysfunction. Results show an overall reduction in capacity for oxidative ATP synthesis fueled by either fatty acid or carbohydrate substrates as well as a reduction in total levels of adenine nucleotides and creatine in myocardium from TAC animals compared to sham-operated controls. Changes in phosphate metabolite levels in the TAC rats are correlated with impaired mechanical function, consistent with the overall hypothesis. Furthermore, computational analysis of myocardial metabolism and contractile dynamics predicts that increased levels of inorganic phosphate in TAC compared to control animals kinetically impair the myosin ATPase crossbridge cycle in decompensated hypertrophy/heart failure.
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Affiliation(s)
- Rachel Lopez
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Bahador Marzban
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Xin Gao
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Ellen Lauinger
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Françoise Van den Bergh
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Steven E Whitesall
- Frankel Cardiovascular Center Physiology and Phenotyping Core, University of Michigan, Ann Arbor, MI, USA
| | - Kimber Converso-Baran
- Frankel Cardiovascular Center Physiology and Phenotyping Core, University of Michigan, Ann Arbor, MI, USA
| | - Charles F Burant
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA,Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Daniel E Michele
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA,Frankel Cardiovascular Center Physiology and Phenotyping Core, University of Michigan, Ann Arbor, MI, USA
| | - Daniel A Beard
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA,Address correspondence to D.A.B. (e-mail: )
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9
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Hankenson FC, Marx JO, Gordon CJ, David JM. Effects of Rodent Thermoregulation on Animal Models in the Research Environment. Comp Med 2018; 68:425-438. [PMID: 30458902 DOI: 10.30802/aalas-cm-18-000049] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
To best promote animal wellbeing and the efficacy of biomedical models, scientific, husbandry, and veterinary professionals must consider the mechanisms, influences, and outcomes of rodent thermoregulation in contemporary research environments. Over the last 2 decades, numerous studies have shown that laboratory mice and rats prefer temperatures that are several degrees warmer than the environments in which they typically are housed within biomedical facilities. Physiologic changes to rodents that are cage-housed under standard temperatures (20 to 26 °C) are attributed to 'cold stress' and include alterations in metabolism, cardiovascular parameters, respiration, and immunologic function. This review article describes common behavioral and physiologic adaptations of laboratory mice and rats to cold stress within modern vivaria, with emphasis on environmental enrichment and effects of anesthesia and procedural support efforts. In addition, potential interventions and outcomes for rodents are presented, relative to the importance of repeating and reproducing experiments involving laboratory rodent research models of human disease.
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Affiliation(s)
- F Claire Hankenson
- Campus Animal Resources, Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - James O Marx
- University Laboratory Animal Resources, Department of Pathobiology, School of Veterinary Medicine; University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Christopher J Gordon
- Toxicity Assessment Division, Neurotoxicology Branch, United States Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - John M David
- Comparative Medicine, Pfizer, La Jolla, California, USA
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10
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Mulla W, Gillis R, Murninkas M, Klapper-Goldstein H, Gabay H, Mor M, Elyagon S, Liel-Cohen N, Bernus O, Etzion Y. Unanesthetized Rodents Demonstrate Insensitivity of QT Interval and Ventricular Refractory Period to Pacing Cycle Length. Front Physiol 2018; 9:897. [PMID: 30050462 PMCID: PMC6050393 DOI: 10.3389/fphys.2018.00897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/21/2018] [Indexed: 12/29/2022] Open
Abstract
Aim: The cardiac electrophysiology of mice and rats has been analyzed extensively, often in the context of pathological manipulations. However, the effects of beating rate on the basic electrical properties of the rodent heart remain unclear. Due to technical challenges, reported electrophysiological studies in rodents are mainly from ex vivo preparations or under deep anesthesia, conditions that might be quite far from the normal physiological state. The aim of the current study was to characterize the ventricular rate-adaptation properties of unanesthetized rats and mice. Methods: An implanted device was chronically implanted in rodents for atrial or ventricular pacing studies. Following recovery from surgery, QT interval was evaluated in rodents exposed to atrial pacing at various frequencies. In addition, the frequency dependence of ventricular refractoriness was tested by conventional ventricular programmed stimulation protocols. Results: Our findings indicate total absence of conventional rate-adaptation properties for both QT interval and ventricular refractoriness. Using monophasic action potential recordings in isolated mice hearts we could confirm the previously reported shortening of the action potential duration at fast pacing rates. However, we found that this mild shortening did not result in similar decrease of ventricular refractory period. Conclusion: Our findings indicate that unanesthetized rodents exhibit flat QT interval and ventricular refractory period rate-dependence. This data argue against empirical use of QT interval correction methods in rodent studies. Our new methodology allowing atrial and ventricular pacing of unanesthetized freely moving rodents may facilitate more appropriate utility of these important animal models in the context of cardiac electrophysiology studies.
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Affiliation(s)
- Wesam Mulla
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Roni Gillis
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Michael Murninkas
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Hadar Klapper-Goldstein
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Hovav Gabay
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Michal Mor
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Sigal Elyagon
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Noah Liel-Cohen
- Cardiology Department, Soroka University Medical Center and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Olivier Bernus
- L'Institut de Rythmologie et Modélisation Cardiaque, l'Institut Hospitalo-Universitaire, Fondation Bordeaux Université, Bordeaux, France
| | - Yoram Etzion
- Cardiac Arrhythmia Research Laboratory, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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11
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Ilkhanizadeh S, Sabelström H, Miroshnikova YA, Frantz A, Zhu W, Idilli A, Lakins JN, Schmidt C, Quigley DA, Fenster T, Yuan E, Trzeciak JR, Saxena S, Lindberg OR, Mouw JK, Burdick JA, Magnitsky S, Berger MS, Phillips JJ, Arosio D, Sun D, Weaver VM, Weiss WA, Persson AI. Antisecretory Factor-Mediated Inhibition of Cell Volume Dynamics Produces Antitumor Activity in Glioblastoma. Mol Cancer Res 2018; 16:777-790. [PMID: 29431617 PMCID: PMC5932284 DOI: 10.1158/1541-7786.mcr-17-0413] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/13/2017] [Accepted: 01/24/2018] [Indexed: 12/31/2022]
Abstract
Interstitial fluid pressure (IFP) presents a barrier to drug uptake in solid tumors, including the aggressive primary brain tumor glioblastoma (GBM). It remains unclear how fluid dynamics impacts tumor progression and can be targeted therapeutically. To address this issue, a novel telemetry-based approach was developed to measure changes in IFP during progression of GBM xenografts. Antisecretory factor (AF) is an endogenous protein that displays antisecretory effects in animals and patients. Here, endogenous induction of AF protein or exogenous administration of AF peptide reduced IFP and increased drug uptake in GBM xenografts. AF inhibited cell volume regulation of GBM cells, an effect that was phenocopied in vitro by the sodium-potassium-chloride cotransporter 1 (SLC12A2/NKCC1) inhibitor bumetanide. As a result, AF induced apoptosis and increased survival in GBM models. In vitro, the ability of AF to reduce GBM cell proliferation was phenocopied by bumetanide and NKCC1 knockdown. Next, AF's ability to sensitize GBM cells to the alkylating agent temozolomide, standard of care in GBM patients, was evaluated. Importantly, combination of AF induction and temozolomide treatment blocked regrowth in GBM xenografts. Thus, AF-mediated inhibition of cell volume regulation represents a novel strategy to increase drug uptake and improve outcome in GBM. Mol Cancer Res; 16(5); 777-90. ©2018 AACR.
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Affiliation(s)
- Shirin Ilkhanizadeh
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
| | - Hanna Sabelström
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | | | - Aaron Frantz
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - Wen Zhu
- Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Aurora Idilli
- Institute of Biophysics, CNR and FBK, Trento, Italy
- CIBIO, University of Trento, Trento, Italy
| | - Jon N Lakins
- Department of Surgery, University of California, San Francisco, San Francisco, California
| | - Christin Schmidt
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - David A Quigley
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California
| | - Trenten Fenster
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - Edith Yuan
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - Jacqueline R Trzeciak
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - Supna Saxena
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
| | - Olle R Lindberg
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
- Department of Pathology, University of California, San Francisco, San Francisco, California
| | - Janna K Mouw
- Department of Surgery, University of California, San Francisco, San Francisco, California
| | - Jason A Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sergey Magnitsky
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California
| | - Mitchel S Berger
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Joanna J Phillips
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
- Department of Pathology, University of California, San Francisco, San Francisco, California
| | - Daniele Arosio
- Institute of Biophysics, CNR and FBK, Trento, Italy
- CIBIO, University of Trento, Trento, Italy
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Valerie M Weaver
- Department of Surgery, University of California, San Francisco, San Francisco, California
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
| | - William A Weiss
- Department of Neurology, University of California, San Francisco, San Francisco, California
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
| | - Anders I Persson
- Department of Neurology, University of California, San Francisco, San Francisco, California.
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
- Sandler Neurosciences Center, University of California, San Francisco, San Francisco, California
- Brain Tumor Research Center (BTRC) at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California
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12
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Pan G, Munukutla S, Kar A, Gardinier J, Thandavarayan RA, Palaniyandi SS. Type-2 diabetic aldehyde dehydrogenase 2 mutant mice (ALDH 2*2) exhibiting heart failure with preserved ejection fraction phenotype can be determined by exercise stress echocardiography. PLoS One 2018; 13:e0195796. [PMID: 29677191 PMCID: PMC5909916 DOI: 10.1371/journal.pone.0195796] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 03/29/2018] [Indexed: 11/21/2022] Open
Abstract
E487K point mutation of aldehyde dehydrogenase (ALDH) 2 (ALDH2*2) in East Asians intrinsically lowers ALDH2 activity. ALDH2*2 is associated with diabetic cardiomyopathy. Diabetic patients exhibit heart failure of preserved ejection fraction (HFpEF) i.e. while the systolic heart function is preserved in them, they may exhibit diastolic dysfunction, implying a jeopardized myocardial health. Currently, it is challenging to detect cardiac functional deterioration in diabetic mice. Stress echocardiography (echo) in the clinical set-up is a procedure used to measure cardiac reserve and impaired cardiac function in coronary artery diseases. Therefore, we hypothesized that high-fat diet fed type-2 diabetic ALDH2*2 mutant mice exhibit HFpEF which can be measured by cardiac echo stress test methodology. We induced type-2 diabetes in 12-week-old male C57BL/6 and ALDH2*2 mice through a high-fat diet. At the end of 4 months of DM induction, we measured the cardiac function in diabetic and control mice of C57BL/6 and ALDH2*2 genotypes by conscious echo. Subsequently, we imposed exercise stress by allowing the mice to run on the treadmill until exhaustion. Post-stress, we measured their cardiac function again. Only after treadmill running, but not at rest, we found a significant decrease in % fractional shortening and % ejection fraction in ALDH2*2 mice with diabetes compared to C57BL/6 diabetic mice as well as non-diabetic (control) ALDH2*2 mice. The diabetic ALDH2*2 mice also exhibited poor maximal running speed and distance. Our data suggest that high-fat fed diabetic ALDH2*2 mice exhibit HFpEF and treadmill exercise stress echo test is able to determine this HFpEF in the diabetic ALDH2*2 mice.
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MESH Headings
- Aldehyde Dehydrogenase, Mitochondrial/genetics
- Animals
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/physiopathology
- Diet, High-Fat/adverse effects
- Echocardiography, Stress
- Heart Failure/diagnostic imaging
- Heart Failure/etiology
- Heart Failure/physiopathology
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Phenotype
- Point Mutation
- Stroke Volume
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Affiliation(s)
- Guodong Pan
- Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Health System, Detroit, MI United States of America
| | - Srikar Munukutla
- Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Health System, Detroit, MI United States of America
| | - Ananya Kar
- Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Health System, Detroit, MI United States of America
| | - Joseph Gardinier
- Bone and Joint Center, Henry Ford Health System, Detroit, MI United States of America
| | - Rajarajan A. Thandavarayan
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX, United States of America
| | - Suresh Selvaraj Palaniyandi
- Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Health System, Detroit, MI United States of America
- Department of Physiology, Wayne State University, Detroit, MI, United States of America
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13
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Lujan HL, DiCarlo SE. Fundamental hemodynamic mechanisms mediating the response to myocardial ischemia in conscious paraplegic mice: cardiac output versus peripheral resistance. Physiol Rep 2017; 5:5/6/e13214. [PMID: 28336819 PMCID: PMC5371571 DOI: 10.14814/phy2.13214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/21/2017] [Accepted: 02/22/2017] [Indexed: 11/25/2022] Open
Abstract
Autonomic dysfunction, a relative sedentary lifestyle, a reduced muscle mass and increased adiposity leads to metabolic abnormalities that accelerate the development of coronary artery disease (CAD) in individuals living with spinal cord injury (SCI). An untoward cardiac incident is related to the degree of CAD, suggesting that the occurrence of a significant cardiac event is significantly higher for individuals with SCI. Thus, understanding the fundamental hemodynamic mechanisms mediating the response to myocardial ischemia has the potential to positively impact individuals and families living with SCI. Accordingly, we systematically investigated if thoracic level 5 spinal cord transection (T5X; paraplegia) alters the arterial blood pressure response to coronary artery occlusion and if the different arterial blood pressure responses to coronary artery occlusion between intact and paraplegic mice are mediated by changes in cardiac output and or systemic peripheral resistance and whether differences in cardiac output are caused by changes in heart rate and or stroke volume. To achieve this goal, the tolerance to 3 min of coronary artery occlusion was determined in conscious intact and paraplegic mice. Paraplegic mice had an impaired ability to maintain arterial blood pressure during coronary artery occlusion as arterial pressure fell to near lethal levels by 1.38 ± 0.64 min. The lower arterial pressure was mediated by a lower cardiac output as systemic peripheral resistance was elevated in paraplegic mice. The lower cardiac output was mediated by a reduced heart rate and stroke volume. These results indicate that in paraplegic mice, the arterial pressure response to coronary artery occlusion is hemodynamically mediated primarily by cardiac output which is determined by heart rate and stroke volume.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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14
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Abstract
Numerous animal cardiac exercise models using animal subjects have been established to uncover the cardiovascular physiological mechanism of exercise or to determine the effects of exercise on cardiovascular health and disease. In most cases, animal-based cardiovascular exercise modalities include treadmill running, swimming, and voluntary wheel running with a series of intensities, times, and durations. Those used animals include small rodents (e.g., mice and rats) and large animals (e.g., rabbits, dogs, goats, sheep, pigs, and horses). Depending on the research goal, each experimental protocol should also describe whether its respective exercise treatment can produce the anticipated acute or chronic cardiovascular adaptive response. In this chapter, we will briefly describe the most common kinds of animal models of acute and chronic cardiovascular exercises that are currently being conducted and are likely to be chosen in the near future. Strengths and weakness of animal-based cardiac exercise modalities are also discussed.
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15
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Lujan HL, Rivers JP, DiCarlo SE. Complex and interacting influences of the autonomic nervous system on cardiac electrophysiology in conscious mice. Auton Neurosci 2016; 201:24-31. [PMID: 27594686 PMCID: PMC5108678 DOI: 10.1016/j.autneu.2016.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/15/2016] [Accepted: 08/28/2016] [Indexed: 01/09/2023]
Abstract
Mice may now be the preferred animal model for biomedical research due to its anatomical, physiological, and genetic similarity to humans. However, little is known about accentuated antagonism of chronotropic and dromotropic properties in conscious mice. Accordingly, we describe the complex and interacting influence of the autonomic nervous system on cardiac electrophysiology in conscious mice. Specifically, we report the effects of single and combined cardiac autonomic blockade on measurements of pulse interval (heart rate), atrio-ventricular interval, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, and Wenckebach cycle length in conscious mice free of the confounding influences of anesthetics and surgical trauma. Autonomic influences were quantified as the change in parameter induced by its selective blocker (Sympathetic or Parasympathetic Effect) or as the difference between the intrinsic value and the value after a selective blocker (Sympathetic or Parasympathetic Tonus). Sympatho-Vagal Balance (SVB) was assessed as the ratio of control interval to intrinsic interval. SVB suggests slight parasympathetic dominance in the control of cardiac electrophysiology intervals. Furthermore, results documents a complex interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system in the control of cardiac electrophysiology parameters. Specifically, the parasympathetic effect was greater than the parasympathetic tonus in the control of cardiac electrophysiology parameters. In contrast, the sympathetic effect was smaller than the sympathetic tonus in the control of cardiac electrophysiology parameters. Results have important implications because actions of pharmacological agents that alter the autonomic control of cardiac electrophysiology are transformed by these interacting mechanisms.
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Affiliation(s)
- Heidi L Lujan
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
| | - Joshua P Rivers
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
| | - Stephen E DiCarlo
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
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16
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Translational assessment of cardiac contractility by echocardiography in the telemetered rat. J Pharmacol Toxicol Methods 2016; 77:24-32. [DOI: 10.1016/j.vascn.2015.09.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/27/2015] [Accepted: 09/15/2015] [Indexed: 11/19/2022]
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17
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Bakermans AJ, Abdurrachim D, van Nierop BJ, Koeman A, van der Kroon I, Baartscheer A, Schumacher CA, Strijkers GJ, Houten SM, Zuurbier CJ, Nicolay K, Prompers JJ. In vivo mouse myocardial (31)P MRS using three-dimensional image-selected in vivo spectroscopy (3D ISIS): technical considerations and biochemical validations. NMR IN BIOMEDICINE 2015; 28:1218-1227. [PMID: 26269430 PMCID: PMC4573916 DOI: 10.1002/nbm.3371] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 06/24/2015] [Accepted: 07/09/2015] [Indexed: 05/31/2023]
Abstract
(31)P MRS provides a unique non-invasive window into myocardial energy homeostasis. Mouse models of cardiac disease are widely used in preclinical studies, but the application of (31)P MRS in the in vivo mouse heart has been limited. The small-sized, fast-beating mouse heart imposes challenges regarding localized signal acquisition devoid of contamination with signal originating from surrounding tissues. Here, we report the implementation and validation of three-dimensional image-selected in vivo spectroscopy (3D ISIS) for localized (31)P MRS of the in vivo mouse heart at 9.4 T. Cardiac (31)P MR spectra were acquired in vivo in healthy mice (n = 9) and in transverse aortic constricted (TAC) mice (n = 8) using respiratory-gated, cardiac-triggered 3D ISIS. Localization and potential signal contamination were assessed with (31)P MRS experiments in the anterior myocardial wall, liver, skeletal muscle and blood. For healthy hearts, results were validated against ex vivo biochemical assays. Effects of isoflurane anesthesia were assessed by measuring in vivo hemodynamics and blood gases. The myocardial energy status, assessed via the phosphocreatine (PCr) to adenosine 5'-triphosphate (ATP) ratio, was approximately 25% lower in TAC mice compared with controls (0.76 ± 0.13 versus 1.00 ± 0.15; P < 0.01). Localization with one-dimensional (1D) ISIS resulted in two-fold higher PCr/ATP ratios than measured with 3D ISIS, because of the high PCr levels of chest skeletal muscle that contaminate the 1D ISIS measurements. Ex vivo determinations of the myocardial PCr/ATP ratio (0.94 ± 0.24; n = 8) confirmed the in vivo observations in control mice. Heart rate (497 ± 76 beats/min), mean arterial pressure (90 ± 3.3 mmHg) and blood oxygen saturation (96.2 ± 0.6%) during the experimental conditions of in vivo (31)P MRS were within the normal physiological range. Our results show that respiratory-gated, cardiac-triggered 3D ISIS allows for non-invasive assessments of in vivo mouse myocardial energy homeostasis with (31)P MRS under physiological conditions.
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Affiliation(s)
- Adrianus J. Bakermans
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Desiree Abdurrachim
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Bastiaan J. van Nierop
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Anneke Koeman
- Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Inge van der Kroon
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Antonius Baartscheer
- Experimental Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Cees A. Schumacher
- Experimental Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Gustav J. Strijkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Sander M. Houten
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, and Department of Pediatrics, Emma Children’s Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Coert J. Zuurbier
- Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jeanine J. Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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18
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Kurtz TW, Lujan HL, DiCarlo SE. The 24 h pattern of arterial pressure in mice is determined mainly by heart rate-driven variation in cardiac output. Physiol Rep 2014; 2:2/11/e12223. [PMID: 25428952 PMCID: PMC4255824 DOI: 10.14814/phy2.12223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Few studies have systematically investigated whether daily patterns of arterial blood pressure over 24 h are mediated by changes in cardiac output, peripheral resistance, or both. Understanding the hemodynamic mechanisms that determine the 24 h patterns of blood pressure may lead to a better understanding of how such patterns become disturbed in hypertension and influence risk for cardiovascular events. In conscious, unrestrained C57BL/6J mice, we investigated whether the 24 h pattern of arterial blood pressure is determined by variation in cardiac output, systemic vascular resistance, or both and also whether variations in cardiac output are mediated by variations in heart rate and or stroke volume. As expected, arterial pressure and locomotor activity were significantly (P < 0.05) higher during the nighttime period compared with the daytime period when mice are typically sleeping (+12.5 ± 1.0 mmHg, [13%] and +7.7 ± 1.3 activity counts, [254%], respectively). The higher arterial pressure during the nighttime period was mediated by higher cardiac output (+2.6 ± 0.3 mL/min, [26%], P < 0.05) in association with lower peripheral resistance (-1.5 ± 0.3 mmHg/mL/min, [-13%] P < 0.05). The increased cardiac output during the nighttime was mainly mediated by increased heart rate (+80.0 ± 16.5 beats/min, [18%] P < 0.05), as stroke volume increased minimally at night (+1.6 ± 0.5 μL per beat, [6%] P < 0.05). These results indicate that in C57BL/6J mice, the 24 h pattern of blood pressure is hemodynamically mediated primarily by the 24 h pattern of cardiac output which is almost entirely determined by the 24 h pattern of heart rate. These findings suggest that the differences in blood pressure between nighttime and daytime are mainly driven by differences in heart rate which are strongly correlated with differences in locomotor activity.
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Affiliation(s)
- Theodore W Kurtz
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, California
| | - Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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19
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Lujan HL, DiCarlo SE. Reperfusion-induced sustained ventricular tachycardia, leading to ventricular fibrillation, in chronically instrumented, intact, conscious mice. Physiol Rep 2014; 2:2/6/e12057. [PMID: 24973331 PMCID: PMC4208649 DOI: 10.14814/phy2.12057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Reperfusion‐induced lethal ventricular arrhythmias are observed during relief of coronary artery spasm, with unstable angina, exercise‐induced ischemia, and silent ischemia. Accordingly, significant efforts are underway to understand the mechanisms responsible for reperfusion‐induced lethal arrhythmias and mice have become increasingly important in these efforts. However, although reperfusion‐induced sustained ventricular tachycardia leading to ventricular fibrillation (VF) has been recorded in many models, reports in mice are sparse and of limited success. Importantly, none of these studies were conducted in intact, conscious mice. Accordingly, a chronically instrumented, intact, conscious murine model of reperfusion‐induced lethal arrhythmias has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of reperfusion‐induced lethal arrhythmias. Male mice (n = 9) were instrumented to record cardiac output and the electrocardiogram. In addition, a snare was placed around the left main coronary artery. Following recovery, the susceptibility to sustained ventricular tachycardia produced by 3 min of occlusion and reperfusion of the left main coronary artery was determined in conscious mice by pulling on the snare. Reperfusion culminated in sustained ventricular tachycardia, leading to VF, in all nine conscious mice. The procedures conducted in conscious C57BL/6J mice, a strain commonly used in transgenic studies, can be utilized in genetically modified models to enhance our understanding of single gene defects on reperfusion‐induced lethal ventricular arrhythmias in intact, conscious, and complex animals. We describe, for the first time, the use of an intact, conscious, murine model of reperfusion‐induced lethal arrhythmias. This model has the potential to be of major importance for advancing the concepts and methods that drive antiarrhythmic therapies.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, 48201, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, 48201, Michigan
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20
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Andreev-Andrievskiy AA, Popova AS, Borovik AS, Dolgov ON, Tsvirkun DV, Custaud M, Vinogradova OL. Stress-associated cardiovascular reaction masks heart rate dependence on physical load in mice. Physiol Behav 2014; 132:1-9. [PMID: 24802359 DOI: 10.1016/j.physbeh.2014.03.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 03/31/2014] [Indexed: 01/29/2023]
Abstract
When tested on the treadmill mice do not display a graded increase of heart rate (HR), but rather a sharp shift of cardiovascular indices to high levels at the onset of locomotion. We hypothesized that under test conditions cardiovascular reaction to physical load in mice is masked with stress-associated HR increase. To test this hypothesis we monitored mean arterial pressure (MAP) and heart rate in C57BL/6 mice after exposure to stressful stimuli, during spontaneous locomotion in the open-field test, treadmill running or running in a wheel installed in the home cage. Mice were treated with β1-adrenoblocker atenolol (2mg/kg ip, A), cholinolytic ipratropium bromide (2mg/kg ip, I), combination of blockers (A+I), anxiolytic diazepam (5mg/kg ip, D) or saline (control trials, SAL). MAP and HR in mice increased sharply after handling, despite 3weeks of habituation to the procedure. Under stressful conditions of open field test cardiovascular parameters in mice were elevated and did not depend on movement speed. HR values did not differ in I and SAL groups and were reduced with A or A+I. HR was lower at rest in D pretreated mice. In the treadmill test HR increase over speeds of 6, 12 and 18m/min was roughly 1/7-1/10 of HR increase observed after placing the mice on the treadmill. HR could not be increased with cholinolytic (I), but was reduced after sympatholytic (A) or A+I treatment. Anxiolytic (D) reduced heart rate at lower speeds of movement and its overall effect was to unmask the dependency of HR on running speed. During voluntary running in non-stressful conditions of the home cage HR in mice linearly increased with increasing running speeds. We conclude that in test situations cardiovascular reactions in mice are governed predominantly by stress-associated sympathetic activation, rendering efforts to evaluate HR and MAP reactions to workload unreliable.
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Affiliation(s)
- A A Andreev-Andrievskiy
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, 76A Khoroshevskoe Shosse, Russia; Lomonosov Moscow State University, Biology Faculty, Moscow 119234, 1/12 Leninskie Gory, Russia.
| | - A S Popova
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, 76A Khoroshevskoe Shosse, Russia; Lomonosov Moscow State University, Biology Faculty, Moscow 119234, 1/12 Leninskie Gory, Russia
| | - A S Borovik
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, 76A Khoroshevskoe Shosse, Russia
| | - O N Dolgov
- Anokhin Institute of Normal Physiology, Russian Academy of Medical Sciences, Moscow 125009, 11/4 Mokhovaya St, Russia
| | - D V Tsvirkun
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, 76A Khoroshevskoe Shosse, Russia
| | - M Custaud
- University of Angers, Rue Haute de Reculée, 49045 Angers Cedex 01, France
| | - O L Vinogradova
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, 76A Khoroshevskoe Shosse, Russia
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21
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Methawasin M, Hutchinson KR, Lee EJ, Smith JE, Saripalli C, Hidalgo CG, Ottenheijm CAC, Granzier H. Experimentally increasing titin compliance in a novel mouse model attenuates the Frank-Starling mechanism but has a beneficial effect on diastole. Circulation 2014; 129:1924-36. [PMID: 24599837 DOI: 10.1161/circulationaha.113.005610] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Experimentally upregulating compliant titins has been suggested as a therapeutic for lowering pathological diastolic stiffness levels. However, how increasing titin compliance impacts global cardiac function requires in-depth study. We investigate the effect of upregulating compliant titins in a novel mouse model with a genetically altered titin splicing factor; integrative approaches were used from intact cardiomyocyte mechanics to pressure-volume analysis and Doppler echocardiography. METHODS AND RESULTS Compliant titins were upregulated through deletion of the RNA Recognition Motif of the splicing factor RBM20 (Rbm20(ΔRRM)mice). A genome-wide exon expression analysis and a candidate approach revealed that the phenotype is likely to be dominated by greatly increased lengths of titin's spring elements. At both cardiomyocyte and left ventricular chamber levels, diastolic stiffness was reduced in heterozygous (+/-) Rbm20(ΔRRM)mice with a further reduction in homozygous (-/-) mice at only the intact myocyte level. Fibrosis was present in only -/- Rbm20(ΔRRM) hearts. The Frank-Starling Mechanism was reduced in a graded fashion in Rbm20(ΔRRM) mice, at both the cardiomyocyte and left ventricular chamber levels. Exercise tests revealed an increase in exercise capacity in +/- mice. CONCLUSIONS Titin is not only important in diastolic but also in systolic cardiac function. Upregulating compliant titins reduces diastolic chamber stiffness owing to the increased compliance of myocytes, but it depresses end-systolic elastance; under conditions of exercise, the beneficial effects on diastolic function dominate. Therapeutic manipulation of the RBM20-based splicing system might be able to minimize effects on fibrosis and systolic function while improving the diastolic function in patients with heart failure.
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Affiliation(s)
- Mei Methawasin
- Sarver Molecular Cardiovascular Research Program, Departments of Physiology and Cellular and Molecular Medicine, University of Arizona, Tucson, AZ (M.M., K.R.H., E.-J.L., J.E.S., C.S., C.G.H., C.A.C.O., H.G.); and Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands (C.A.C.O.)
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22
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Hidalgo C, Saripalli C, Granzier HL. Effect of exercise training on post-translational and post-transcriptional regulation of titin stiffness in striated muscle of wild type and IG KO mice. Arch Biochem Biophys 2014; 552-553:100-7. [PMID: 24603287 DOI: 10.1016/j.abb.2014.02.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 02/03/2014] [Accepted: 02/23/2014] [Indexed: 01/09/2023]
Abstract
Exercise has beneficial effects on diastolic dysfunction but the underlying mechanisms are not well understood. Here we studied the effects of exercise on the elastic protein titin, an important determinant of diastolic stiffness, in both the left ventricle and the diaphragm. We used wild type mice and genetically engineered mice with HFpEF symptoms (IG KO mice), including diastolic dysfunction. In the diaphragm muscle, exercise increased the expression level of titin (increased titin:MHC ratio) which is expected to increase titin-based stiffness. This effect was absent in the LV. We also studied the constitutively expressed titin residues S11878 and S12022 that are known targets of CaMKIIδ and PKCα with increased phosphorylation resulting in an increase in titin-based passive stiffness. The phosphorylation level of S11878 was unchanged whereas S12022 responded to exercise with a reduction in the phosphorylation level in the LV and, interestingly, an increase in the diaphragm. These changes are expected to lower titin's stiffness in the LV and increase stiffness in the diaphragm. We propose that these disparate effects reflect the unique physiological needs of the two tissue types and that both effects are beneficial.
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Affiliation(s)
- Carlos Hidalgo
- Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, United States
| | - Chandra Saripalli
- Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, United States
| | - Henk L Granzier
- Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, United States.
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23
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Milani-Nejad N, Janssen PML. Small and large animal models in cardiac contraction research: advantages and disadvantages. Pharmacol Ther 2014; 141:235-49. [PMID: 24140081 PMCID: PMC3947198 DOI: 10.1016/j.pharmthera.2013.10.007] [Citation(s) in RCA: 305] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 08/15/2013] [Indexed: 12/22/2022]
Abstract
The mammalian heart is responsible for not only pumping blood throughout the body but also adjusting this pumping activity quickly depending upon sudden changes in the metabolic demands of the body. For the most part, the human heart is capable of performing its duties without complications; however, throughout many decades of use, at some point this system encounters problems. Research into the heart's activities during healthy states and during adverse impacts that occur in disease states is necessary in order to strategize novel treatment options to ultimately prolong and improve patients' lives. Animal models are an important aspect of cardiac research where a variety of cardiac processes and therapeutic targets can be studied. However, there are differences between the heart of a human being and an animal and depending on the specific animal, these differences can become more pronounced and in certain cases limiting. There is no ideal animal model available for cardiac research, the use of each animal model is accompanied with its own set of advantages and disadvantages. In this review, we will discuss these advantages and disadvantages of commonly used laboratory animals including mouse, rat, rabbit, canine, swine, and sheep. Since the goal of cardiac research is to enhance our understanding of human health and disease and help improve clinical outcomes, we will also discuss the role of human cardiac tissue in cardiac research. This review will focus on the cardiac ventricular contractile and relaxation kinetics of humans and animal models in order to illustrate these differences.
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Affiliation(s)
- Nima Milani-Nejad
- Department of Physiology and Cell Biology and D. Davis Heart Lung Institute, College of Medicine, The Ohio State University, OH, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology and D. Davis Heart Lung Institute, College of Medicine, The Ohio State University, OH, USA.
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24
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Lujan HL, DiCarlo SE. Cardiac electrophysiology and the susceptibility to sustained ventricular tachycardia in intact, conscious mice. Am J Physiol Heart Circ Physiol 2014; 306:H1213-21. [PMID: 24561859 DOI: 10.1152/ajpheart.00780.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac electrophysiological dysfunction is a major cause of death in humans. Accordingly, electrophysiological testing is routinely performed in intact, conscious, humans to evaluate arrhythmias and disorders of cardiac conduction. However, to date, in vivo electrophysiological studies in mice are limited to anesthetized open-chest or closed-chest preparations. However, cardiac electrophysiology in anesthetized mice or mice with surgical trauma may not adequately represent what occurs in conscious mice. Accordingly, an intact, conscious murine model of cardiac electrophysiology has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of cardiac electrophysiology. The conscious mouse model permits measurements of atrioventricular interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, Wenckebach cycle length, the ventricular effective refractory period (VERP) and the electrical stimulation threshold to induce sustained ventricular tachyarrhythmias in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This is an important consideration because anesthesia and surgical trauma markedly reduced cardiac output and heart rate as well as altered cardiac electrophysiology parameters. Most importantly, anesthesia and surgical trauma significantly increased the VERP and virtually eliminated the ability to induce sustained ventricular tachyarrhythmias. Accordingly, the methodology allows for the accurate documentation of cardiac electrophysiology in complex, conscious mice and may be adopted for advancing the concepts and ideas that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Lujan HL, Janbaih H, DiCarlo SE. Dynamic interaction between the heart and its sympathetic innervation following T5 spinal cord transection. J Appl Physiol (1985) 2012; 113:1332-41. [PMID: 22723636 DOI: 10.1152/japplphysiol.00522.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Midthoracic spinal cord injury (SCI) is associated with enhanced sympathetic support of heart rate as well as myocardial damage related to calcium overload. The myocardial damage may elicit an enhanced sympathetic support of contractility to maintain ventricular function. In contrast, the level of inotropic drive may be reduced to match the lower afterload that results from the injury-induced reduction in arterial pressure. Accordingly, the inotropic response to midthoracic SCI may be increased or decreased but has not been investigated and therefore remains unknown. Furthermore, the altered ventricular function may be associated with anatomical changes in cardiac sympathetic innervation. To determine the inotropic drive following midthoracic SCI, a telemetry device was used for repeated measurements of left ventricular (LV) function, with and without beta-adrenergic receptor blockade, in rats before and after midthoracic SCI or sham SCI. In addition, NGF content (ELISA) and dendritic arborization (cholera toxin B immunohistochemistry and Sholl analysis) of cardiac-projecting sympathetic postganglionic neurons in the stellate ganglia were determined. Midthoracic SCI was associated with an enhanced sympathetic support of heart rate, dP/dt(+), and dP/dt(-). Importantly, cardiac function was lower following blockade of the sympathetic nervous system in rats with midthoracic SCI compared with sham-operated rats. Finally, these functional neuroplastic changes were associated with an increased NGF content and structural neuroplasticity within the stellate ganglia. Results document impaired LV function with codirectional changes in chronotropic and inotropic responses following midthoracic SCI. These functional changes were associated with a dynamic interaction between the heart and its sympathetic innervation.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield Ave., Detroit, MI 48201, USA
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