1
|
Sato H, Nagano T, Satoh W, Kumasaka K, Shindoh C, Miura M. Roles of stretch-activated channels and NADPH oxidase 2 in the induction of twitch contraction by muscle stretching in rat ventricular muscle. Pflugers Arch 2022; 474:355-363. [PMID: 35066611 DOI: 10.1007/s00424-021-02657-5] [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: 10/19/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/28/2022]
Abstract
Mechano-electric feedback means that muscle stretching causes depolarization of membrane potential. We investigated whether muscle stretching induces action potential and twitch contraction with a threshold of sarcomere length (SL) and what roles stretch-activated channels (SACs) and stretch-activated NADPH oxidase (X-ROS signaling) play in the induction. Trabeculae were obtained from the right ventricles of rat hearts. Force, SL, and [Ca2+]i were measured. Various degrees of stretching from the SL of 2.0 μm were applied 0.5 s after the last stimulus of the electrical train with 0.4-s intervals for 7.5 s. The SLtwitch was defined as the minimal SL at which twitch contraction was induced by the stretching. Muscle stretching induced twitch contraction with a threshold of SL at 0.4-s stimulus intervals ([Ca2+]o = 0.7 mmol/L). The SLtwitch was not changed by increasing the stimulus intervals and [Ca2+]o and by adding 1 μmol/L isoproterenol. The SLtwitch was not changed by adding 10 μmol/L Gd3+, 100 μmol/L or 200 μmol/L streptomycin, and 5 μmol/L GsMTx4. The SLtwitch was not changed by adding 1 μmol/L ryanodine and 3 μmol/L diphenyleneiodonium chloride. In contrast, the SLtwitch was increased by elevating extracellular K+ from 5 to 10 mmol/L and by adding the stretching during the refractory period of membrane potential. The addition of the stretching-induced twitch contraction more frequently induced arrhythmias. These results suggest that muscle stretching can induce twitch contraction with a threshold of SL and concern the occurrence of arrhythmias and that SACs and X-ROS signaling play no roles in the induction.
Collapse
Affiliation(s)
- Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Tsuyoshi Nagano
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Wakako Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Kazunori Kumasaka
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan.
| |
Collapse
|
2
|
Cui H, Schaff HV, Nishimura RA, Geske JB, Dearani JA, Newman DB, Ommen SR. Preoperative left ventricular longitudinal strain predicts outcome of septal myectomy for obstructive hypertrophic cardiomyopathy. J Thorac Cardiovasc Surg 2021:S0022-5223(21)01414-8. [PMID: 34763894 DOI: 10.1016/j.jtcvs.2021.09.058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/14/2021] [Accepted: 09/17/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The objective of this study was to determine the characteristics of longitudinal strain and its effect on outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM) who underwent septal myectomy. METHODS We reviewed patients with obstructive HCM who underwent septal myectomy at our clinic from 2007 to 2016. Data of those who had strain echocardiography within 6 months before isolated myectomy were analyzed. RESULTS The median age of the 857 patients studied was 55 (interquartile range [IQR], 44-63) years, and 451 (52.6%) were male. Left ventricular ejection fraction was 71% (IQR, 67%-74%), and the resting peak outflow tract gradient was 58 (IQR, 27-85) mm Hg. The median global longitudinal strain (GLS) was -14.6% (IQR, -12.0% to -17.3%). Regional longitudinal strain was nonuniform as reflected by more normal values in apical segments and more abnormal in basal segments. Moreover, GLS correlated poorly with ejection fraction and outflow tract gradient. In 64 patients who had postoperative strain echocardiography, GLS was comparable before and after septal myectomy, but regional strain was more uniform after myectomy. Over a follow-up of 8.3 (IQR, 6.5-10.3) years, when patients were equally stratified according to GLS (cutoff, -14.64%), the group with worse GLS had significantly poorer survival compared with the better GLS group (P = .002). Left ventricular ejection fraction had no association with survival. CONCLUSIONS Left ventricular longitudinal strain is nonuniform and might be significantly reduced in patients with obstructive HCM. Septal myectomy does not impair GLS but is associated with more uniform regional strains. Most importantly, reduced GLS preoperatively is strongly and independently associated with increased all-cause mortality after septal myectomy for obstructive HCM.
Collapse
Affiliation(s)
- Hao Cui
- Department of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn
| | | | - Rick A Nishimura
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minn
| | - Jeffrey B Geske
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minn
| | - Joseph A Dearani
- Department of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn
| | - Darrell B Newman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minn
| | - Steve R Ommen
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minn
| |
Collapse
|
3
|
Zhang X, Zhang J, Ji X, Wei Z, Ding B, Liu G, Lv X, Zheng Y, Zhan S. A Quantitative Serum Proteomic Analysis Helps to Explore the Comprehensive Mechanism and Identify Serum Biomarkers of Shengmai Injection's Effect on Isoproterenol-Induced Myocardial Ischemia in Rats. Front Pharmacol 2021; 12:666429. [PMID: 33995093 PMCID: PMC8113823 DOI: 10.3389/fphar.2021.666429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/30/2021] [Indexed: 12/12/2022] Open
Abstract
Shengmai injection (SMI), a traditional Chinese medicine formula with the nature of multicomponent and multi-target, has been widely used in clinic for treating cardiovascular diseases in China; however, its comprehensive mechanism of action remains unclear. In this study, a TMT-based quantitative serum proteomics was performed to explore SMI’s global mechanism and help identify serum biomarkers of its effect on isoproterenol (ISO)-induced myocardial ischemia rats. The results of TMT-based proteomic analysis identified 227, 100, and 228 differentially expressed proteins (DEPs) for the model compared to the control group, SMI pretreatment + model compared to the model group, and SMI pretreatment + model compared to the control group, respectively. Based on bioinformatics analyses of gene ontology (GO), KEGG pathways, and the protein-protein interaction (PPI) networks for the DEPs, it is concluded that the comprehensive mechanism of SMI’s effect on ISO-induced myocardial ischemia injury includes regulation of energy metabolism, reducing endothelial cell permeability, regulation of vessel and cardiac contractility, anti-inflammation, and prevention of cell apoptosis. Furthermore, 10 common DEPs were found, and six of them were regulated in model vs. control group, while back-regulated in SMI pretreatment + model vs. model group. Among them, three functional proteins of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Fas apoptotic inhibitory molecule 3 (FAIM3), and uncharacterized protein (M0R5J4), which were verified by the PRM analysis, might be the potential serum biomarkers on SMI’s effects. Overall, this serum proteomics of SMI not only provides insights into the comprehensive mechanism underlying SMI’s effects on ischemic heart disease but also helps identify serum biomarkers for directing SMI’s cardioprotective effects.
Collapse
Affiliation(s)
- Xiaoping Zhang
- Department of Science and Education, the First Hospital of Jiaxing, Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Jie Zhang
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Xiangyu Ji
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Zhenzhen Wei
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Baoyue Ding
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Guoqiang Liu
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Xiaoqing Lv
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Yongxia Zheng
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| | - Shuyu Zhan
- Department of Pharmacy, College of Medicine, Jiaxing University, Jiaxing, China
| |
Collapse
|
4
|
Monma Y, Shindo T, Eguchi K, Kurosawa R, Kagaya Y, Ikumi Y, Ichijo S, Nakata T, Miyata S, Matsumoto A, Sato H, Miura M, Kanai H, Shimokawa H. Low-intensity pulsed ultrasound ameliorates cardiac diastolic dysfunction in mice: a possible novel therapy for heart failure with preserved left ventricular ejection fraction. Cardiovasc Res 2021; 117:1325-1338. [PMID: 32683442 DOI: 10.1093/cvr/cvaa221] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/30/2020] [Accepted: 07/14/2020] [Indexed: 01/01/2023] Open
Abstract
AIMS Heart failure with preserved left ventricular ejection fraction (HFpEF) is a serious health problem worldwide, as no effective therapy is yet available. We have previously demonstrated that our low-intensity pulsed ultrasound (LIPUS) therapy is effective and safe for angina and dementia. In this study, we aimed to examine whether the LIPUS therapy also ameliorates cardiac diastolic dysfunction in mice. METHODS AND RESULTS Twelve-week-old obese diabetic mice (db/db) and their control littermates (db/+) were treated with either the LIPUS therapy [1.875 MHz, 32 cycles, Ispta (spatial peak temporal average intensity) 117-162 mW/cm2, 0.25 W/cm2] or placebo procedure two times a week for 4 weeks. At 20-week-old, transthoracic echocardiography and invasive haemodynamic analysis showed that cardiac diastolic function parameters, such as e', E/e', end-diastolic pressure-volume relationship, Tau, and dP/dt min, were all deteriorated in placebo-treated db/db mice compared with db/+ mice, while systolic function was preserved. Importantly, these cardiac diastolic function parameters were significantly ameliorated in the LIPUS-treated db/db mice. We also measured the force (F) and intracellular Ca2+ ([Ca2+]i) in trabeculae dissected from ventricles. We found that relaxation time and [Ca2+]i decay (Tau) were prolonged during electrically stimulated twitch contractions in db/db mice, both of which were significantly ameliorated in the LIPUS-treated db/db mice, indicating that the LIPUS therapy also improves relaxation properties at tissue level. Functionally, exercise capacity was also improved in the LIPUS-treated db/db mice. Histologically, db/db mice displayed progressed cardiomyocyte hypertrophy and myocardial interstitial fibrosis, while those changes were significantly suppressed in the LIPUS-treated db/db mice. Mechanistically, western blot showed that the endothelial nitric oxide synthase (eNOS)-nitric oxide (NO)-cGMP-protein kinase G (PKG) pathway and Ca2+-handling molecules were up-regulated in the LIPUS-treated heart. CONCLUSIONS These results indicate that the LIPUS therapy ameliorates cardiac diastolic dysfunction in db/db mice through improvement of eNOS-NO-cGMP-PKG pathway and cardiomyocyte Ca2+-handling system, suggesting its potential usefulness for the treatment of HFpEF patients.
Collapse
MESH Headings
- Animals
- Calcium Signaling
- Cyclic GMP-Dependent Protein Kinases/metabolism
- Disease Models, Animal
- Fibrosis
- Heart Failure, Diastolic/genetics
- Heart Failure, Diastolic/metabolism
- Heart Failure, Diastolic/physiopathology
- Heart Failure, Diastolic/therapy
- Isolated Heart Preparation
- Mice, Knockout
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Nitric Oxide/metabolism
- Nitric Oxide Synthase Type III/metabolism
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Stroke Volume
- Ultrasonic Therapy
- Ultrasonic Waves
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/metabolism
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Dysfunction, Left/therapy
- Ventricular Function, Left
- Mice
Collapse
Affiliation(s)
- Yuto Monma
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Tomohiko Shindo
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Kumiko Eguchi
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Ryo Kurosawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Yuta Kagaya
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Yosuke Ikumi
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Sadamitsu Ichijo
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Takashi Nakata
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Satoshi Miyata
- Department of Evidence-Based Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ayana Matsumoto
- Department of Clinical Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Haruka Sato
- Department of Clinical Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Masahito Miura
- Department of Clinical Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroshi Kanai
- Department of Electronic Engineering, Tohoku University Graduate School of Engineering, Sendai, Japan
- Division of Biomedical Measurements and Diagnostics, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
| | - Hiroaki Shimokawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| |
Collapse
|
5
|
Miura M, Hasegawa T, Matsumoto A, Nishiyama M, Someya Y, Satoh W, Kumasaka K, Shindoh C, Sato H. Effect of transient elevation of glucose on contractile properties in non-diabetic rat cardiac muscle. Heart Vessels 2020; 36:568-576. [PMID: 33226494 DOI: 10.1007/s00380-020-01726-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 11/06/2020] [Indexed: 10/22/2022]
Abstract
In non-diabetic patients with severe disease, such as acute myocardial infarction or acute heart failure, admission blood glucose level is associated with their short-term and long-term mortality. We examined whether transient elevation of glucose affects contractile properties in non-diabetic hearts. Force, intracellular Ca2+ ([Ca2+]i), and sarcomere length were measured in trabeculae from rat hearts. To assess contractile properties, maximum velocity of contraction (Max dF/dt) and minimum velocity of relaxation (Min dF/dt) were calculated. The ratio of phosphorylated troponin I (P-TnI) to troponin I (TnI) was measured. One hour after elevation of glucose from 150 to 400 mg/dL, developed force, Max dF/dt, and Min dF/dt were reduced without changes in [Ca2+]i transients at 2.5 Hz stimulation and 2.0 mM [Ca2+]o, while developed force and [Ca2+]i transients showed no changes at 0.5 Hz stimulation and 0.7 mM [Ca2+]o. In the presence of 1 μM KN-93, a Ca2+/calmodulin-dependent protein kinaseII (CaMKII) inhibitor, or 50 μM diazo-5-oxonorleucine, a L-glutamine-D-fructose-6-phosphate amidotransferase inhibitor, the reduction of contractile properties after elevation of glucose was suppressed. Furthermore, 1 h after elevation of glucose to 400 mg/dL at 2.0 mM [Ca2+]o, the ratio of P-TnI to TnI was increased. These results suggest that in non-diabetic hearts under higher Ca2+-load, transient elevation of glucose for 1 h reduces contractile properties probably by activating CaMKII through O-GlcNAcylation. Thus, in the patients with severe disease, transient elevation of blood glucose, such as due to stress, may worsen cardiac function and thereby affect their mortality without known diabetes.
Collapse
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
| | - Taiki Hasegawa
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Ayana Matsumoto
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Masami Nishiyama
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Yuka Someya
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Wakako Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Kazunori Kumasaka
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| |
Collapse
|
6
|
Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
Collapse
Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| |
Collapse
|
7
|
Cameron BA, Kai H, Kaihara K, Iribe G, Quinn TA. Ischemia Enhances the Acute Stretch-Induced Increase in Calcium Spark Rate in Ventricular Myocytes. Front Physiol 2020; 11:289. [PMID: 32372969 PMCID: PMC7179564 DOI: 10.3389/fphys.2020.00289] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/16/2020] [Indexed: 12/20/2022] Open
Abstract
Introduction: In ventricular myocytes, spontaneous release of calcium (Ca2+) from the sarcoplasmic reticulum via ryanodine receptors (“Ca2+ sparks”) is acutely increased by stretch, due to a stretch-induced increase of reactive oxygen species (ROS). In acute regional ischemia there is stretch of ischemic tissue, along with an increase in Ca2+ spark rate and ROS production, each of which has been implicated in arrhythmogenesis. Yet, whether there is an impact of ischemia on the stretch-induced increase in Ca2+ sparks and ROS has not been investigated. We hypothesized that ischemia would enhance the increase of Ca2+ sparks and ROS that occurs with stretch. Methods: Isolated ventricular myocytes from mice (male, C57BL/6J) were loaded with fluorescent dye to detect Ca2+ sparks (4.6 μM Fluo-4, 10 min) or ROS (1 μM DCF, 20 min), exposed to normal Tyrode (NT) or simulated ischemia (SI) solution (hyperkalemia [15 mM potassium], acidosis [6.5 pH], and metabolic inhibition [1 mM sodium cyanide, 20 mM 2-deoxyglucose]), and subjected to sustained stretch by the carbon fiber technique (~10% increase in sarcomere length, 15 s). Ca2+ spark rate and rate of ROS production were measured by confocal microscopy. Results: Baseline Ca2+ spark rate was greater in SI (2.54 ± 0.11 sparks·s−1·100 μm−2; n = 103 cells, N = 10 mice) than NT (0.29 ± 0.05 sparks·s−1·100 μm−2; n = 33 cells, N = 9 mice; p < 0.0001). Stretch resulted in an acute increase in Ca2+ spark rate in both SI (3.03 ± 0.13 sparks·s−1·100 μm−2; p < 0.0001) and NT (0.49 ± 0.07 sparks·s−1·100 μm−2; p < 0.0001), with the increase in SI being greater than NT (+0.49 ± 0.04 vs. +0.20 ± 0.04 sparks·s−1·100 μm−2; p < 0.0001). Baseline rate of ROS production was also greater in SI (1.01 ± 0.01 normalized slope; n = 11, N = 8 mice) than NT (0.98 ± 0.01 normalized slope; n = 12, N = 4 mice; p < 0.05), but there was an acute increase with stretch only in SI (+12.5 ± 2.6%; p < 0.001). Conclusion: Ischemia enhances the stretch-induced increase of Ca2+ sparks in ventricular myocytes, with an associated enhancement of stretch-induced ROS production. This effect may be important for premature excitation and/or in the development of an arrhythmogenic substrate in acute regional ischemia.
Collapse
Affiliation(s)
- Breanne A Cameron
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Hiroaki Kai
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Keiko Kaihara
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Gentaro Iribe
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan.,Department of Physiology, Asahikawa Medical University, Asahikawa, Japan
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
| |
Collapse
|
8
|
Izu LT, Kohl P, Boyden PA, Miura M, Banyasz T, Chiamvimonvat N, Trayanova N, Bers DM, Chen-Izu Y. Mechano-electric and mechano-chemo-transduction in cardiomyocytes. J Physiol 2020; 598:1285-1305. [PMID: 31789427 PMCID: PMC7127983 DOI: 10.1113/jp276494] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/21/2019] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction (E-C) coupling is influenced by (at least) three dynamic systems that couple and feedback to one another (see Abstract Figure). Here we review the mechanical effects on cardiomyocytes that include mechano-electro-transduction (commonly referred to as mechano-electric coupling, MEC) and mechano-chemo-transduction (MCT) mechanisms at cell and molecular levels which couple to Ca2+ -electro and E-C coupling reviewed elsewhere. These feedback loops from muscle contraction and mechano-transduction to the Ca2+ homeodynamics and to the electrical excitation are essential for understanding the E-C coupling dynamic system and arrhythmogenesis in mechanically loaded hearts. This white paper comprises two parts, each reflecting key aspects from the 2018 UC Davis symposium: MEC (how mechanical load influences electrical dynamics) and MCT (how mechanical load alters cell signalling and Ca2+ dynamics). Of course, such separation is artificial since Ca2+ dynamics profoundly affect ion channels and electrogenic transporters and vice versa. In time, these dynamic systems and their interactions must become fully integrated, and that should be a goal for a comprehensive understanding of how mechanical load influences cell signalling, Ca2+ homeodynamics and electrical dynamics. In this white paper we emphasize current understanding, consensus, controversies and the pressing issues for future investigations. Space constraints make it impossible to cover all relevant articles in the field, so we will focus on the topics discussed at the symposium.
Collapse
Affiliation(s)
- Leighton T. Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre, and Faculty of Medicine, University of Freiburg, D-79110, Germany
| | | | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
| | - Natalia Trayanova
- Department of Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| |
Collapse
|
9
|
Mantziari L, Butcher C, Shi R, Kontogeorgis A, Opel A, Chen Z, Haldar S, Panikker S, Hussain W, Jones DG, Gatzoulis MA, Markides V, Ernst S, Wong T. Characterization of the Mechanism and Substrate of Atrial Tachycardia Using Ultra-High-Density Mapping in Adults With Congenital Heart Disease: Impact on Clinical Outcomes. J Am Heart Assoc 2020; 8:e010535. [PMID: 30773973 PMCID: PMC6405650 DOI: 10.1161/jaha.118.010535] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background Atrial tachycardia (AT) is common in patients with adult congenital heart disease and is challenging to map and ablate. We used ultra‐high‐density mapping to characterize the AT mechanism and investigate whether substrate characteristics are related to ablation outcomes. Methods and Results A total of 50 ATs were mapped with ultra‐high‐density mapping in 23 procedures. Patients were followed up for up to 12 months. Procedures were classified to group A if there was 1 single AT induced (n=12) and group B if there were ≥2 ATs induced (n=11 procedures). AT mechanism per procedure was macro re‐entry (n=10) and localized re‐entry (n=2) in group A and multiple focal (n=6) or multiple macro re‐entry (n=5) in group B. Procedure duration, low voltage area (0.05–0.5 mV), and low voltage area indexed for volume were higher in group B (159 [147–180] versus 412 [352–420] minutes, P<0.001, 22.6 [12.2–29.8] versus 54.2 [51.1–61.6] cm2, P=0.014 and 0.17 [0.12–0.21] versus 0.26 [0.23–0.27] cm2/mL, P=0.024 accordingly). Dense scar (<0.05 mV) and atrial volume were similar between groups. Acute success and freedom from arrhythmia recurrence were worse in group B (100% versus 77% P=0.009 and 11.3, CI 9.8–12.7 versus 4.9, CI 2.2–7.6 months, log rank P=0.004). Indexed low voltage area ≥0.24 cm2/mL could predict recurrence with 100% sensitivity and 77% specificity (area under the curve 0.923, P=0.007). Conclusions Larger low voltage area but not dense scar is associated with the induction of multiple focal or re‐entry ATs, which are subsequently associated with longer procedure duration and worse acute and midterm clinical outcomes.
Collapse
Affiliation(s)
- Lilian Mantziari
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Charles Butcher
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Rui Shi
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | | | - Aaisha Opel
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Zhong Chen
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Shouvik Haldar
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Sandeep Panikker
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Wajid Hussain
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - David Gareth Jones
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | | | - Vias Markides
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Sabine Ernst
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| | - Tom Wong
- 1 Royal Brompton and Harefield NHS Foundation Trust London United Kingdom
| |
Collapse
|
10
|
Miura M, Handoh T, Taguchi Y, Hasegawa T, Takahashi Y, Morita N, Matsumoto A, Shindoh C, Sato H. Transient Elevation of Glucose Increases Arrhythmia Susceptibility in Non-Diabetic Rat Trabeculae With Non-Uniform Contraction. Circ J 2020; 84:551-558. [PMID: 32092718 DOI: 10.1253/circj.cj-19-0715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND In non-diabetic patients with acute coronary syndrome, stress hyperglycemia occasionally occurs and is related to their mortality. Whether transient elevation of glucose affects arrhythmia susceptibility in non-diabetic hearts with non-uniform contraction was examined.Methods and Results:Force, intracellular Ca2+([Ca2+]i), and membrane potential were measured in trabeculae from rat hearts. Non-uniform contraction was produced by a jet of paralyzing solution. Ca2+waves and arrhythmias were induced by electrical stimulation (2.0 mmol/L [Ca2+]o). The activity of Ca2+/calmodulin-dependent protein kinaseII (CaMKII) was measured. An elevation of glucose from 150 to 400 mg/dL increased the velocity of Ca2+waves and the number of spontaneous action potentials triggered by electrical stimulation. Besides, the elevation of glucose increased the CaMKII activity. In the presence of 1 μmol/L KN-93, the elevation of glucose did not increase the velocity of Ca2+waves and the number of triggered action potentials. In addition, in the presence of 1 μmol/L autocamtide-2 related inhibitory peptide or 50 μmol/L diazo-5-oxonorleucine, the elevation of glucose did not increase the number of triggered action potentials. Furthermore, the elevation of glucose by adding L-glucose did not increase their number. CONCLUSIONS In non-diabetic hearts with non-uniform contraction, transient elevation of glucose increases the velocity of Ca2+waves by activating CaMKII,probably through glycosylation with O-linked β-N-acetylglucosamine, thereby increasing arrhythmia susceptibility.
Collapse
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tetsuya Handoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yuhto Taguchi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Taiki Hasegawa
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yui Takahashi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Natsuki Morita
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Ayana Matsumoto
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| |
Collapse
|
11
|
Different roles of myocardial ROCK1 and ROCK2 in cardiac dysfunction and postcapillary pulmonary hypertension in mice. Proc Natl Acad Sci U S A 2018; 115:E7129-E7138. [PMID: 29987023 DOI: 10.1073/pnas.1721298115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Although postcapillary pulmonary hypertension (PH) is an important prognostic factor for patients with heart failure (HF), its pathogenesis remains to be fully elucidated. To elucidate the different roles of Rho-kinase isoforms, ROCK1 and ROCK2, in cardiomyocytes in response to chronic pressure overload, we performed transverse aortic constriction (TAC) in cardiac-specific ROCK1-deficient (cROCK1-/-) and ROCK2-deficient (cROCK2-/-) mice. Cardiomyocyte-specific ROCK1 deficiency promoted pressure-overload-induced cardiac dysfunction and postcapillary PH, whereas cardiomyocyte-specific ROCK2 deficiency showed opposite results. Histological analysis showed that pressure-overload-induced cardiac hypertrophy and fibrosis were enhanced in cROCK1-/- mice compared with controls, whereas cardiac hypertrophy was attenuated in cROCK2-/- mice after TAC. Consistently, the levels of oxidative stress were up-regulated in cROCK1-/- hearts and down-regulated in cROCK2-/- hearts compared with controls after TAC. Furthermore, cyclophilin A (CyPA) and basigin (Bsg), both of which augment oxidative stress, enhanced cardiac dysfunction and postcapillary PH in cROCK1-/- mice, whereas their expressions were significantly lower in cROCK2-/- mice. In clinical studies, plasma levels of CyPA were significantly increased in HF patients and were higher in patients with postcapillary PH compared with those without it. Finally, high-throughput screening demonstrated that celastrol, an antioxidant and antiinflammatory agent, reduced the expressions of CyPA and Bsg in the heart and the lung, ameliorating cardiac dysfunction and postcapillary PH induced by TAC. Thus, by differentially affecting CyPA and Bsg expressions, ROCK1 protects and ROCK2 jeopardizes the heart from pressure-overload HF with postcapillary PH, for which celastrol may be a promising agent.
Collapse
|
12
|
Regional increase in ROS within stretched region exacerbates arrhythmias in rat trabeculae with nonuniform contraction. Pflugers Arch 2018; 470:1349-1357. [DOI: 10.1007/s00424-018-2152-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/28/2018] [Accepted: 05/01/2018] [Indexed: 12/29/2022]
|
13
|
Mahmoudi M, Yu M, Serpooshan V, Wu JC, Langer R, Lee RT, Karp JM, Farokhzad OC. Multiscale technologies for treatment of ischemic cardiomyopathy. NATURE NANOTECHNOLOGY 2017; 12:845-855. [PMID: 28875984 PMCID: PMC5717755 DOI: 10.1038/nnano.2017.167] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 07/13/2017] [Indexed: 05/02/2023]
Abstract
The adult mammalian heart possesses only limited capacity for innate regeneration and the response to severe injury is dominated by the formation of scar tissue. Current therapy to replace damaged cardiac tissue is limited to cardiac transplantation and thus many patients suffer progressive decay in the heart's pumping capacity to the point of heart failure. Nanostructured systems have the potential to revolutionize both preventive and therapeutic approaches for treating cardiovascular disease. Here, we outline recent advancements in nanotechnology that could be exploited to overcome the major obstacles in the prevention of and therapy for heart disease. We also discuss emerging trends in nanotechnology affecting the cardiovascular field that may offer new hope for patients suffering massive heart attacks.
Collapse
Affiliation(s)
- Morteza Mahmoudi
- Center for Nanomedicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Department of Anesthesiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Nanotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran 13169-43551, Iran
| | - Mikyung Yu
- Center for Nanomedicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Department of Anesthesiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Vahid Serpooshan
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Joseph C. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, California 94305, USA
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Robert Langer
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Richard T. Lee
- Department of Stem Cell and Regenerative Biology, Harvard University, Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
- Department of Medicine, Division of Cardiology, Brigham and Women’s Hospital and Harvard Medical School, Cambridge, Massachusetts 02138, USA
| | - Jeffrey M. Karp
- Center for Nanomedicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Omid C. Farokhzad
- Center for Nanomedicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Department of Anesthesiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Nanotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran 13169-43551, Iran
| |
Collapse
|
14
|
Timmermann V, Dejgaard LA, Haugaa KH, Edwards AG, Sundnes J, McCulloch AD, Wall ST. An integrative appraisal of mechano-electric feedback mechanisms in the heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:404-417. [PMID: 28851517 DOI: 10.1016/j.pbiomolbio.2017.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/12/2017] [Accepted: 08/18/2017] [Indexed: 12/20/2022]
Abstract
Mechanically-induced alterations in cardiac electrophysiology are referred to as mechano-electric feedback (MEF), and play an important role in electrical regulation of cardiac performance. The influence of mechanical stress and strain on electrophysiology has been investigated at all levels, however the role of MEF in arrhythmia remains poorly understood. During the normal contraction of the heart, mechano-sensitive processes are an implicit component of cardiac activity. Under abnormal mechanical events, stretch-activated mechanisms may contribute to local or global changes in electrophysiology (EP). While such mechanisms have been hypothesised to be involved in mechanically-initiated arrhythmias, the details of these mechanisms and their importance remain elusive. We assess the theoretical role of stretch mechanisms using coupled models of cellular electrophysiology and sarcomere contraction dynamics. Using models of single ventricular myocytes, we first investigated the potential MEF contributions of stretch-activated currents (SAC), and stretch-induced myofilament calcium release, to test how strain and fibrosis may alter cellular electrophysiology. For all models investigated, SACs were alone not sufficient to create a pro-arrhythmic perturbation of the action potential with stretch. However, when combined with stretch-induced myofilament calcium release, the action potential could be shortened depending on the timing of the strain. This effect was highly model dependent, with a canine epicardial EP model being the most sensitive. These model results suggest that known mechanisms of mechano-electric coupling in cardiac myocyte may be sufficient to be pro-arrhythmic, but only in combination and under specific strain patterns.
Collapse
Affiliation(s)
- Viviane Timmermann
- Simula Research Laboratory, Martin Linges vei 25, Fornebu, 1364, Norway; Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway; University California San Diego, 9500 Gilman Drive, La Jolla, CA, United States; University of Oslo, Gaustadallen 23 B, Oslo, 0373, Norway.
| | - Lars A Dejgaard
- Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway; Department of Cardiology, Oslo University Hospital, Norway
| | - Kristina H Haugaa
- Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway; Department of Cardiology, Oslo University Hospital, Norway
| | - Andrew G Edwards
- Simula Research Laboratory, Martin Linges vei 25, Fornebu, 1364, Norway; Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway; University of Oslo, Gaustadallen 23 B, Oslo, 0373, Norway
| | - Joakim Sundnes
- Simula Research Laboratory, Martin Linges vei 25, Fornebu, 1364, Norway; Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway; University of Oslo, Gaustadallen 23 B, Oslo, 0373, Norway
| | - Andrew D McCulloch
- University California San Diego, 9500 Gilman Drive, La Jolla, CA, United States
| | - Samuel T Wall
- Simula Research Laboratory, Martin Linges vei 25, Fornebu, 1364, Norway; Center for Cardiological Innovation, Songsvannsveien 9, Oslo, 0372, Norway.
| |
Collapse
|
15
|
Baumeister P, Quinn TA. Altered Calcium Handling and Ventricular Arrhythmias in Acute Ischemia. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2016; 10:61-69. [PMID: 28008297 PMCID: PMC5158122 DOI: 10.4137/cmc.s39706] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/27/2016] [Accepted: 11/20/2016] [Indexed: 12/14/2022]
Abstract
Acute ischemia results in deadly cardiac arrhythmias that are a major contributor to sudden cardiac death (SCD). The electrophysiological changes involved have been extensively studied, yet the mechanisms of ventricular arrhythmias during acute ischemia remain unclear. What is known is that during acute ischemia both focal (ectopic excitation) and nonfocal (reentry) arrhythmias occur, due to an interaction of altered electrical, mechanical, and biochemical properties of the myocardium. There is particular interest in the role that alterations in intracellular calcium handling, which cause changes in intracellular calcium concentration and to the calcium transient, play in ischemia-induced arrhythmias. In this review, we briefly summarize the known contributors to ventricular arrhythmias during acute ischemia, followed by an in-depth examination of the potential contribution of altered intracellular calcium handling, which may include novel targets for antiarrhythmic therapy.
Collapse
Affiliation(s)
- Peter Baumeister
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
| |
Collapse
|
16
|
Miura M, Nagano T, Murai N, Taguchi Y, Handoh T, Satoh M, Miyata S, Miller L, Shindoh C, Stuyvers BD. Effect of Carbenoxolone on Arrhythmogenesis in Rat Ventricular Muscle. Circ J 2016; 80:76-84. [DOI: 10.1253/circj.cj-15-0401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tsuyoshi Nagano
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Naomi Murai
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yuhto Taguchi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tetsuya Handoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Minami Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Satoshi Miyata
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
| | - Lawson Miller
- Faculty of Medicine, Biomedical Sciences, Memorial University
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | | |
Collapse
|
17
|
Effect of myofilament Ca(2+) sensitivity on Ca(2+) wave propagation in rat ventricular muscle. J Mol Cell Cardiol 2015; 84:162-9. [PMID: 25953256 DOI: 10.1016/j.yjmcc.2015.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 04/02/2015] [Accepted: 04/29/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND The propagation velocity of Ca(2+) waves determines delayed afterdepolarization and affects the occurrence of triggered arrhythmias in cardiac muscle. We focused on myofilament Ca(2+) sensitivity, investigating how the velocity of Ca(2+) waves responds to its increased sensitivity resulting from muscle stretch or the addition of a myofilament Ca(2+) sensitizer, SCH00013. We further investigated whether production of reactive oxygen species (ROS) may be involved in the change in velocity. METHODS Trabeculae were obtained from rat hearts. Force, sarcomere length, and [Ca(2+)]i were measured. ROS production was estimated from 2',7'-dichlorofluorescein (DCF) fluorescence. Trabeculae were exposed to a 10 mM Ca(2+) jet for the induction of Ca(2+) leak from the sarcoplasmic reticulum in its exposed region. Ca(2+) waves were induced by 2.5-Hz stimulus trains for 7.5s (24 °C, 2.0 mM [Ca(2+)]o). Muscle stretch of 5, 10, and 15% was applied 300 ms after the last stimulus of the train. RESULTS Muscle stretch increased the DCF fluorescence, the amplitude of aftercontractions, and the velocity of Ca(2+) waves depending on the degree of stretch. After preincubation with 3 μM diphenyleneiodonium (DPI), muscle stretch increased only the amplitude of aftercontractions but not the DCF fluorescence nor the velocity of Ca(2+) waves. SCH00013 (30 μM) increased the DCF fluorescence, the amplitude of aftercontractions, and the velocity of Ca(2+) waves. DPI suppressed these increases. CONCLUSIONS Muscle stretch increases the velocity of Ca(2+) waves by increasing ROS production, not by increasing myofilament Ca(2+) sensitivity. In the case of SCH00013, ROS production increases myofilament Ca(2+) sensitivity and the velocity of Ca(2+) waves. These results suggest that ROS rather than myofilament Ca(2+) sensitivity plays an important role in the determination of the velocity of Ca(2+) waves, that is, arrhythmogenesis.
Collapse
|
18
|
Solovyova O, Katsnelson LB, Konovalov PV, Kursanov AG, Vikulova NA, Kohl P, Markhasin VS. The cardiac muscle duplex as a method to study myocardial heterogeneity. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:115-28. [PMID: 25106702 PMCID: PMC4210666 DOI: 10.1016/j.pbiomolbio.2014.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 07/25/2014] [Indexed: 12/14/2022]
Abstract
This paper reviews the development and application of paired muscle preparations, called duplex, for the investigation of mechanisms and consequences of intra-myocardial electro-mechanical heterogeneity. We illustrate the utility of the underlying combined experimental and computational approach for conceptual development and integration of basic science insight with clinically relevant settings, using previously published and new data. Directions for further study are identified.
Collapse
Affiliation(s)
- O Solovyova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia.
| | - L B Katsnelson
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P V Konovalov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - A G Kursanov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
| | - N A Vikulova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P Kohl
- National Heart and Lung Institute, Imperial College of London, Heart Science Centre, Harefield Hospital, Hill End Road, Harefield UB9 6JH, UK; Department of Computer Sciences, University of Oxford, UK
| | - V S Markhasin
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
| |
Collapse
|
19
|
Arrhythmogenic effects by local left ventricular stretch: effects of flecainide and streptomycin. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:763-75. [DOI: 10.1007/s00210-014-0988-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 04/29/2014] [Indexed: 12/20/2022]
|
20
|
The importance of non-uniformities in mechano-electric coupling for ventricular arrhythmias. J Interv Card Electrophysiol 2013; 39:25-35. [DOI: 10.1007/s10840-013-9852-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 10/16/2013] [Indexed: 12/31/2022]
|
21
|
Hohendanner F, Ljubojević S, MacQuaide N, Sacherer M, Sedej S, Biesmans L, Wakula P, Platzer D, Sokolow S, Herchuelz A, Antoons G, Sipido K, Pieske B, Heinzel FR. Intracellular dyssynchrony of diastolic cytosolic [Ca²⁺] decay in ventricular cardiomyocytes in cardiac remodeling and human heart failure. Circ Res 2013; 113:527-38. [PMID: 23825358 DOI: 10.1161/circresaha.113.300895] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
RATIONALE Synchronized release of Ca²⁺ into the cytosol during each cardiac cycle determines cardiomyocyte contraction. OBJECTIVE We investigated synchrony of cytosolic [Ca²⁺] decay during diastole and the impact of cardiac remodeling. METHODS AND RESULTS Local cytosolic [Ca²⁺] transients (1-µm intervals) were recorded in murine, porcine, and human ventricular single cardiomyocytes. We identified intracellular regions of slow (slowCaR) and fast (fastCaR) [Ca²⁺] decay based on the local time constants of decay (TAUlocal). The SD of TAUlocal as a measure of dyssynchrony was not related to the amplitude or the timing of local Ca²⁺ release. Stimulation of sarcoplasmic reticulum Ca²⁺ ATPase with forskolin or istaroxime accelerated and its inhibition with cyclopiazonic acid slowed TAUlocal significantly more in slowCaR, thus altering the relationship between SD of TAUlocal and global [Ca²⁺] decay (TAUglobal). Na⁺/Ca²⁺ exchanger inhibitor SEA0400 prolonged TAUlocal similarly in slowCaR and fastCaR. FastCaR were associated with increased mitochondrial density and were more sensitive to the mitochondrial Ca²⁺ uniporter blocker Ru360. Variation in TAUlocal was higher in pig and human cardiomyocytes and higher with increased stimulation frequency (2 Hz). TAUlocal correlated with local sarcomere relengthening. In mice with myocardial hypertrophy after transverse aortic constriction, in pigs with chronic myocardial ischemia, and in end-stage human heart failure, variation in TAUlocal was increased and related to cardiomyocyte hypertrophy and increased mitochondrial density. CONCLUSIONS In cardiomyocytes, cytosolic [Ca²⁺] decay is regulated locally and related to local sarcomere relengthening. Dyssynchronous intracellular [Ca²⁺] decay in cardiac remodeling and end-stage heart failure suggests a novel mechanism of cellular contractile dysfunction.
Collapse
Affiliation(s)
- Felix Hohendanner
- Division of Cardiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Venkataraman R, Baldo MP, Hwang HS, Veltri T, Pinto JR, Baudenbacher FJ, Knollmann BC. Myofilament calcium de-sensitization and contractile uncoupling prevent pause-triggered ventricular tachycardia in mouse hearts with chronic myocardial infarction. J Mol Cell Cardiol 2013; 60:8-15. [PMID: 23570978 PMCID: PMC3683590 DOI: 10.1016/j.yjmcc.2013.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/11/2013] [Accepted: 03/30/2013] [Indexed: 11/16/2022]
Abstract
Myocardial infarction (MI) is a major risk for ventricular arrhythmia. Pause-triggered ventricular arrhythmia can be caused by increased myofilament Ca binding due to sarcomeric mutations or Ca-sensitizing compounds. Myofilament Ca sensitivity is also increased after MI. Here we hypothesize that MI increases risk for pause-triggered ventricular arrhythmias, which can be prevented by myofilament Ca-desensitization and contractile uncoupling. To test this hypothesis, we generated a murine chronic MI model using male B6SJLF1/J mice (n=40) that underwent permanent ligation of the left anterior descending coronary artery. 4 weeks post MI, cardiac structure, function and myofilament Ca sensitivity were evaluated. Pause-dependent arrhythmia susceptibility was quantified in isolated hearts with pacing trains of increasing frequency, followed by a pause and an extra stimulus. Coronary ligation resulted in a mean infarct size of 39.6±5.7% LV and fractional shortening on echocardiography was reduced by 40% compared to non-infarcted controls. Myofilament Ca sensitivity was significantly increased in post MI hearts (pCa50: Control=5.66±0.03; MI=5.84±0.05; P<0.01). Exposure to the Ca desensitizer/contractile uncoupler blebbistatin (BLEB, 3 μM) reduced myofilament Ca sensitivity of MI hearts to that of control hearts and selectively reduced the frequency of post-pause ectopic beats (MI 0.12±0.04 vs MI+BLEB 0.01±0.005 PVC/pause; P=0.02). BLEB also reduced the incidence of ventricular tachycardia in chronic MI hearts from 59% to 10% (P<0.05). We conclude that chronic MI hearts exhibit increased myofilament Ca sensitivity and pause-triggered ventricular arrhythmias, which can be prevented by blebbistatin. Decreasing myofilament Ca sensitivity may be a strategy to reduce arrhythmia burden after MI.
Collapse
Affiliation(s)
- Raghav Venkataraman
- Department of Biomedical Engineering and Physics, Vanderbilt University, Nashville, TN 37232-0575, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Miura M, Murai N, Hattori T, Nagano T, Stuyvers BD, Shindoh C. Role of reactive oxygen species and Ca(2+) dissociation from the myofilaments in determination of Ca(2+) wave propagation in rat cardiac muscle. J Mol Cell Cardiol 2012; 56:97-105. [PMID: 23266595 DOI: 10.1016/j.yjmcc.2012.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 11/14/2012] [Accepted: 12/10/2012] [Indexed: 11/30/2022]
Abstract
Ca(2+) waves are initiated not only by Ca(2+) leak from the sarcoplasmic reticulum (SR), but also by Ca(2+) dissociation from the myofilaments in the myocardium with nonuniform contraction. We investigated whether contractile properties and the production of reactive oxygen species (ROS) affect Ca(2+) wave propagation. Trabeculae were obtained from 76 rat hearts. Force was measured with a strain gauge, sarcomere length with a laser diffraction technique, and [Ca(2+)](i) with fura-2 and a CCD camera (24°C, 2.0mmol/L [Ca(2+)](o)). ROS production was estimated from 2',7'-dichlorofluorescein (DCF) fluorescence. Trabeculae were regionally exposed to a jet of solution containing 1) 10mmol/L Ca(2+) to initiate Ca(2+) waves by SR Ca(2+) leak due to Ca(2+) overload within the jet-exposed region, and 2) 0.2mmol/L Ca(2+) or 5mmol/L caffeine to initiate such waves by Ca(2+) dissociation from the myofilaments due to nonuniform contraction. Ca(2+) waves were induced by stimulus trains for 7.5s. Ten-percent muscle stretch increased DCF fluorescence and accelerated Ca(2+) waves initiated due to both Ca(2+) overload and nonuniform contraction. Preincubation with 3μmol/L diphenyleneiodonium or 10μmol/L colchicine suppressed the increase in DCF fluorescence but suppressed acceleration of Ca(2+) waves initiated only due to Ca(2+) overload. Irrespective of preincubation with colchicine, reduction of force after the addition of 10μmol/L blebbistatin did not decelerate Ca(2+) waves initiated due to Ca(2+) overload, while it did decelerate waves initiated due to nonuniform contraction. These results suggest that Ca(2+) wave propagation is modulated by ROS production through an intact microtubule network only during stretch and may be additionally modulated by Ca(2+) dissociated from the myofilaments in the case of nonuniform contraction.
Collapse
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan.
| | | | | | | | | | | |
Collapse
|
24
|
Abstract
Heart attack remains the leading cause of death in both men and women worldwide. Stem cell-based therapies, including the use of engineered cardiac tissues, have the potential to treat the massive cell loss and pathological remodeling resulting from heart attack. Specifically, embryonic and induced pluripotent stem cells are a promising source for generation of therapeutically relevant numbers of functional cardiomyocytes and engineering of cardiac tissues in vitro. This review will describe methodologies for successful differentiation of pluripotent stem cells towards the cardiovascular cell lineages as they pertain to the field of cardiac tissue engineering. The emphasis will be placed on comparing the functional maturation in engineered cardiac tissues and developing heart and on methods to quantify cardiac electrical and mechanical function at different spatial scales.
Collapse
Affiliation(s)
- Brian Liau
- Department of Biomedical Engineering, Faculty of Cardiology, Duke University, Room 136 Hudson Hall, Durham, NC 27708, USA
| | | | | |
Collapse
|
25
|
Miura M, Hattori T, Murai N, Nagano T, Nishio T, Boyden PA, Shindoh C. Regional increase in extracellular potassium can be arrhythmogenic due to nonuniform muscle contraction in rat ventricular muscle. Am J Physiol Heart Circ Physiol 2012; 302:H2301-9. [PMID: 22447939 DOI: 10.1152/ajpheart.01161.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the ischemic myocardium, extracellular potassium ([K(+)](o)) increases to ≥20 mmol/l. To determine how lethal arrhythmias occur during ischemia, we investigated whether the increased spatial pattern of [K(+)](o), i.e., a regional or a global increase, affects the incidence of arrhythmias. Force, sarcomere length, membrane potential, and nonuniform intracellular Ca(2+) ([Ca(2+)](i)) were measured in rat ventricular trabeculae. A "regional" or "global" increase in [K(+)](o) was produced by exposing a restricted region of muscle to a jet of 30 mmol/l KCl or by superfusing trabeculae with a solution containing 30 mmol/l KCl, respectively. The increase in [Ca(2+)](i) (Ca(CW)) during Ca(2+) waves was measured (24°C, 3.0 mmol/l [Ca(2+)](o)). A regional increase in [K(+)](o) caused nonuniform [Ca(2+)](i) and contraction. In the presence of isoproterenol, the regional increase in [K(+)](o) induced sustained arrhythmias in 10 of 14 trabeculae, whereas the global increase did not induce such arrhythmias. During sustained arrhythmias, Ca(2+) surged within the jet-exposed region. In the absence of isoproterenol, the regional increase in [K(+)](o) increased Ca(CW), whereas the global increase decreased it. This increase in Ca(CW) with the regional increase in [K(+)](o) was not suppressed by 100 μmol/l streptomycin, whereas it was suppressed by 1) a combination of 10 μmol/l cilnidipine and 3 μmol/l SEA0400; 2) 20 mmol/l 2,3-butanedione monoxime; and 3) 10 μmol/l blebbistatin. A regional but not a global increase in [K(+)](o) induces sustained arrhythmias, probably due to nonuniform excitation-contraction coupling. The same mechanism may underlie arrhythmias during ischemia.
Collapse
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | | | | | | | | | | | | |
Collapse
|
26
|
Bootman MD, Smyrnias I, Thul R, Coombes S, Roderick HL. Atrial cardiomyocyte calcium signalling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:922-34. [DOI: 10.1016/j.bbamcr.2011.01.030] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 01/21/2011] [Accepted: 01/25/2011] [Indexed: 11/25/2022]
|
27
|
Miura M, Hirose M, Endoh H, Wakayama Y, Sugai Y, Nakano M, Fukuda K, Shindoh C, Shirato K, Shimokawa H. Acceleration of Ca2+ waves in monocrotaline-induced right ventricular hypertrophy in the rat. Circ J 2011; 75:1343-9. [PMID: 21467666 DOI: 10.1253/circj.cj-10-1050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Triggered arrhythmias arise from delayed afterdepolarizations (DADs), with Ca(2+) waves playing an important role in their formation. In ventricular hypertrophy, however, it remains unclear how Ca(2+) waves change their propagation features and affect arrhythmogenesis. We addressed this important issue in a rat model of hypertrophy. METHODS AND RESULTS Rats were given a subcutaneous injection of 60 mg/kg monocrotaline (MCT-rats) or solvent (Ctr-rats). After 4 weeks, MCT-rats showed high right ventricular (RV) pressure and RV hypertrophy. Trabeculae were dissected from 36 right ventricles. The force was measured using a silicon strain gauge and regional intracellular Ca(2+) ([Ca(2+)](i)) was determined using microinjected fura-2. Reproducible Ca(2+) waves were induced by stimulus trains (2 Hz, 7.5s). MCT-rats showed a higher diastolic [Ca(2+)](i) and faster and larger Ca(2+) waves (P<0.01). The velocity and amplitude of Ca(2+) waves were correlated with the diastolic [Ca(2+)](i) both in the Ctr- and MCT-rats. The velocity of Ca(2+) waves in the MCT-rats was larger at the given amplitude of Ca(2+) waves than that in the Ctr-rats (P < 0.01). The amplitude of DADs was correlated with the velocity and amplitude of Ca(2+) waves in the Ctr- and MCT-rats. CONCLUSIONS The results suggest that an increase in diastolic [Ca(2+)](i) and an increase in Ca(2+) sensitivity of the sarcoplasmic reticulum Ca(2+) release channel accelerate Ca(2+) waves in ventricular hypertrophy, thereby causing arrhythmogenesis.
Collapse
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Thireau J, Pasquié JL, Martel E, Le Guennec JY, Richard S. New drugs vs. old concepts: a fresh look at antiarrhythmics. Pharmacol Ther 2011; 132:125-45. [PMID: 21420430 DOI: 10.1016/j.pharmthera.2011.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/01/2011] [Indexed: 01/10/2023]
Abstract
Common arrhythmias, particularly atrial fibrillation (AF) and ventricular tachycardia/fibrillation (VT/VF) are a major public health concern. Classic antiarrhythmic (AA) drugs for AF are of limited effectiveness, and pose the risk of life-threatening VT/VF. For VT/VF, implantable cardiac defibrillators appear to be the unique, yet unsatisfactory, solution. Very few AA drugs have been successful in the last few decades, due to safety concerns or limited benefits in comparison to existing therapy. The Vaughan-Williams classification (one drug for one molecular target) appears too restrictive in light of current knowledge of molecular and cellular mechanisms. New AA drugs such as atrial-specific and/or multichannel blockers, upstream therapy and anti-remodeling drugs, are emerging. We focus on the cellular mechanisms related to abnormal Na⁺ and Ca²⁺ handling in AF, heart failure, and inherited arrhythmias, and on novel strategies aimed at normalizing ionic homeostasis. Drugs that prevent excessive Na⁺ entry (ranolazine) and aberrant diastolic Ca²⁺ release via the ryanodine receptor RyR2 (rycals, dantrolene, and flecainide) exhibit very interesting antiarrhythmic properties. These drugs act by normalizing, rather than blocking, channel activity. Ranolazine preferentially blocks abnormal persistent (vs. normal peak) Na⁺ currents, with minimal effects on normal channel function (cell excitability, and conduction). A similar "normalization" concept also applies to RyR2 stabilizers, which only prevent aberrant opening and diastolic Ca²⁺ leakage in diseased tissues, with no effect on normal function during systole. The different mechanisms of action of AA drugs may increase the therapeutic options available for the safe treatment of arrhythmias in a wide variety of pathophysiological situations.
Collapse
Affiliation(s)
- Jérôme Thireau
- Inserm U1046 Physiologie & Médecine Expérimentale du Cœur et des Muscles, Université Montpellier-1, Université Montpellier-2, 34295 Montpellier Cedex 5, France
| | | | | | | | | |
Collapse
|
29
|
Stretch increases the force by decreasing cross-bridge weakening rate in the rat cardiac trabeculae. J Mol Cell Cardiol 2010; 49:962-71. [DOI: 10.1016/j.yjmcc.2010.09.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 11/20/2022]
|