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Ritzer A, Roeschl T, Nay S, Rudakova E, Volk T. Rapid Pacing Decreases L-type Ca 2+ Current and Alters Cacna1c Isogene Expression in Primary Cultured Rat Left Ventricular Myocytes. J Membr Biol 2023; 256:257-269. [PMID: 36995425 DOI: 10.1007/s00232-023-00284-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 03/14/2023] [Indexed: 03/31/2023]
Abstract
The L-type calcium current (ICaL) is the first step in cardiac excitation-contraction-coupling and plays an important role in regulating contractility, but also in electrical and mechanical remodeling. Primary culture of cardiomyocytes, a widely used tool in cardiac ion channel research, is associated with substantial morphological, functional and electrical changes some of which may be prevented by electrical pacing. We therefore investigated ICaL directly after cell isolation and after 24 h of primary culture with and without regular pacing at 1 and 3 Hz in rat left ventricular myocytes. Moreover, we analyzed total mRNA expression of the pore forming subunit of the L-type Ca2+ channel (cacna1c) as well as the expression of splice variants of its exon 1 that contribute to specificity of ICaL in different tissue such as cardiac myocytes or smooth muscle. 24 h incubation without pacing decreased ICaL density by ~ 10% only. Consistent with this decrease we observed a decrease in the expression of total cacna1c and of exon 1a, the dominant variant of cardiomyocytes, while expression of exon 1b and 1c increased. Pacing for 24 h at 1 and 3 Hz led to a substantial decrease in ICaL density by 30%, mildly slowed ICaL inactivation and shifted steady-state inactivation to more negative potentials. Total cacna1c mRNA expression was substantially decreased by pacing, as was the expression of exon 1b and 1c. Taken together, electrical silence introduces fewer alterations in ICaL density and cacna1c mRNA expression than pacing for 24 h and should therefore be the preferred approach for primary culture of cardiomyocytes.
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Affiliation(s)
- Anne Ritzer
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Tobias Roeschl
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Sandra Nay
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Elena Rudakova
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Tilmann Volk
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany.
- Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany.
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Kotsopoulou I, Vyas AK, Cory MJ, Chan CS, Jagarapu J, Gill S, Mudduluru M, Angelis D. Developmental changes of the fetal and neonatal thyroid gland and functional consequences on the cardiovascular system. J Perinatol 2022; 42:1576-1586. [PMID: 36376450 DOI: 10.1038/s41372-022-01559-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 11/16/2022]
Abstract
Thyroid hormones play an important role in the development and function of the cardiac myocyte. Dysregulation of the thyroid hormone milieu affects the fetal cardiac cells via complex molecular mechanisms, either by altering gene expression or directly by affecting post-translational processes. This review offers a comprehensive summary of the effects of thyroid hormones on the developing cardiovascular system and its adaptation. Furthermore, we will highlight the gaps in knowledge and provide suggestions for future research.
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Affiliation(s)
- Ioanna Kotsopoulou
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Arpita K Vyas
- Division of Pediatrics and Endocrinology, College of Medicine, California Northstate University, Elk Grove, CA, USA
| | - Melinda J Cory
- Division of Cardiology, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Christina S Chan
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jawahar Jagarapu
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shamaila Gill
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Manjula Mudduluru
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Dimitrios Angelis
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Gluvic Z, Obradovic M, Stewart AJ, Essack M, Pitt SJ, Samardzic V, Soskic S, Gojobori T, Isenovic ER. Levothyroxine Treatment and the Risk of Cardiac Arrhythmias - Focus on the Patient Submitted to Thyroid Surgery. Front Endocrinol (Lausanne) 2021; 12:758043. [PMID: 34803920 PMCID: PMC8600254 DOI: 10.3389/fendo.2021.758043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/11/2021] [Indexed: 02/05/2023] Open
Abstract
Levothyroxine (LT4) is used to treat frequently encountered endocrinopathies such as thyroid diseases. It is regularly used in clinical (overt) hypothyroidism cases and subclinical (latent) hypothyroidism cases in the last decade. Suppressive LT4 therapy is also part of the medical regimen used to manage thyroid malignancies after a thyroidectomy. LT4 treatment possesses dual effects: substituting new-onset thyroid hormone deficiency and suppressing the local and distant malignancy spreading in cancer. It is the practice to administer LT4 in less-than-high suppressive doses for growth control of thyroid nodules and goiter, even in patients with preserved thyroid function. Despite its approved safety for clinical use, LT4 can sometimes induce side-effects, more often recorded with patients under treatment with LT4 suppressive doses than in unintentionally LT4-overdosed patients. Cardiac arrhythmias and the deterioration of osteoporosis are the most frequently documented side-effects of LT4 therapy. It also lowers the threshold for the onset or aggravation of cardiac arrhythmias for patients with pre-existing heart diseases. To improve the quality of life in LT4-substituted patients, clinicians often prescribe higher doses of LT4 to reach low normal TSH levels to achieve cellular euthyroidism. In such circumstances, the risk of cardiac arrhythmias, particularly atrial fibrillation, increases, and the combined use of LT4 and triiodothyronine further complicates such risk. This review summarizes the relevant available data related to LT4 suppressive treatment and the associated risk of cardiac arrhythmia.
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Affiliation(s)
- Zoran Gluvic
- Clinic for Internal Medicine, Department of Endocrinology and Diabetes, Zemun Clinical Hospital, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Milan Obradovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Alan J. Stewart
- School of Medicine, University of St Andrews, St Andrews, United Kingdom
| | - Magbubah Essack
- King Abdullah University of Science and Technology (KAUST), Computer, Electrical, and Mathematical Sciences and Engineering (CEMSE) Division, Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Samantha J. Pitt
- School of Medicine, University of St Andrews, St Andrews, United Kingdom
| | - Vladimir Samardzic
- Clinic for Internal Medicine, Department of Endocrinology and Diabetes, Zemun Clinical Hospital, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Sanja Soskic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Takashi Gojobori
- King Abdullah University of Science and Technology (KAUST), Computer, Electrical, and Mathematical Sciences and Engineering (CEMSE) Division, Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Esma R. Isenovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
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4
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Wang P, Wei M, Zhu X, Liu Y, Yoshimura K, Zheng M, Liu G, Kume S, Morishima M, Kurokawa T, Ono K. Nitric oxide down-regulates voltage-gated Na + channel in cardiomyocytes possibly through S-nitrosylation-mediated signaling. Sci Rep 2021; 11:11273. [PMID: 34050231 PMCID: PMC8163867 DOI: 10.1038/s41598-021-90840-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/18/2021] [Indexed: 11/24/2022] Open
Abstract
Nitric oxide (NO) is produced from endothelial cells and cardiomyocytes composing the myocardium and benefits cardiac function through both vascular-dependent and—independent effects. This study was purposed to investigate the possible adverse effect of NO focusing on the voltage-gated Na+ channel in cardiomyocytes. We carried out patch-clamp experiments on rat neonatal cardiomyocytes demonstrating that NOC-18, an NO donor, significantly reduced Na+ channel current in a dose-dependent manner by a long-term application for 24 h, accompanied by a reduction of Nav1.5-mRNA and the protein, and an increase of a transcription factor forkhead box protein O1 (FOXO1) in the nucleus. The effect of NOC-18 on the Na+ channel was blocked by an inhibitor of thiol oxidation N-ethylmaleimide, a disulfide reducing agent disulfide 1,4-Dithioerythritol, or a FOXO1 activator paclitaxel, suggesting that NO is a negative regulator of the voltage-gated Na+ channel through thiols in regulatory protein(s) for the channel transcription.
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Affiliation(s)
- Pu Wang
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China.,Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Mengyan Wei
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China.,Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Xiufang Zhu
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China.,Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Yangong Liu
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China.,Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Kenshi Yoshimura
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Mingqi Zheng
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China
| | - Gang Liu
- Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, 050031, Hebei Province, People's Republic of China
| | - Shinichiro Kume
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Masaki Morishima
- Department of Food Science and Nutrition, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Tatsuki Kurokawa
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan.
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Liu C, Lv H, Li Q, Fu S, Tan J, Wang C, Wang X, Ma Y. Effect of thyrotropin suppressive therapy on heart rate variability and QT dispersion in patients with differentiated thyroid cancer. Medicine (Baltimore) 2020; 99:e21190. [PMID: 32664162 PMCID: PMC7360250 DOI: 10.1097/md.0000000000021190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 05/29/2020] [Accepted: 06/07/2020] [Indexed: 11/26/2022] Open
Abstract
The effects of thyrotropin (TSH) suppressive therapy on autonomic regulation and ventricular repolarization in patients with differentiated thyroid cancer (DTC) have not been elucidated. The aim of present study was to evaluate variation in heart rate variability (HRV) and QT dispersion after TSH suppressive therapy in patients with DTC.Cases, defined as 271 patients with DTC within 1 year of exogenous levothyroxine, and all patients underwent a full history, physical examination, including standard 12 lead electrocardiogram (ECG), and 24 h ambulatory ECG monitoring (Holter) with normal free thyroxine (FT4) and free triiodothyronine (FT3) with levothyroxine. To evaluate effects of TSH suppressive therapy on HRV and QT dispersion, patients were divided into three groups according to different levels of TSH: TSH < 0.1 mIU/L group and 0.1 ≤ TSH < 0.5 mIU/L group were as TSH suppression groups, and 0.5 ≤ TSH < 2.0 mIU/L group was as TSH replacement group.Comparing with 0.5 ≤ TSH < 2.0 mIU/L group, significant changes in both time and frequency domain of HRV and QT dispersion were observed in TSH < 0.1 mIU/L group (P < .001: SDNN, SDANN, HF, LF/HF, QTd, and QTcd; P < .05: rMSSD) and 0.1 ≤ TSH < 0.5 mIU/L group (P < .001: SDNN, HF, LF/HF, QTd, and QTcd), and especially were more pronounced in TSH < 0.1 mIU/L group. Moreover, we found that TSH level was proportional to SDNN (β = 15.829, P < .001), but inversely proportional to LF/HF (β = -0.671, P < .001), QTd (β = -16.674, P < .001) and QTcd (β = -18.314, P < .001) in DTC patients with exogenous levothyroxine.Compared with euthyroid state, patients with suppressed serum TSH have increased sympathetic activity in the presence of diminished vagal tone, ultimately showed sympathovagal imbalance and with an increased inhomogeneity of ventricular recovery times. These findings revealed that TSH suppression therapy had a significant impact on cardiovascular system and had certain guiding role in the treatment and management of patients with DTC.
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6
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Tribulova N, Kurahara LH, Hlivak P, Hirano K, Szeiffova Bacova B. Pro-Arrhythmic Signaling of Thyroid Hormones and Its Relevance in Subclinical Hyperthyroidism. Int J Mol Sci 2020; 21:E2844. [PMID: 32325836 PMCID: PMC7215427 DOI: 10.3390/ijms21082844] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/18/2022] Open
Abstract
A perennial task is to prevent the occurrence and/or recurrence of most frequent or life-threatening cardiac arrhythmias such as atrial fibrillation (AF) and ventricular fibrillation (VF). VF may be lethal in cases without an implantable cardioverter defibrillator or with failure of this device. Incidences of AF, even the asymptomatic ones, jeopardize the patient's life due to its complication, notably the high risk of embolic stroke. Therefore, there has been a growing interest in subclinical AF screening and searching for novel electrophysiological and molecular markers. Considering the worldwide increase in cases of thyroid dysfunction and diseases, including thyroid carcinoma, we aimed to explore the implication of thyroid hormones in pro-arrhythmic signaling in the pathophysiological setting. The present review provides updated information about the impact of altered thyroid status on both the occurrence and recurrence of cardiac arrhythmias, predominantly AF. Moreover, it emphasizes the importance of both thyroid status monitoring and AF screening in the general population, as well as in patients with thyroid dysfunction and malignancies. Real-world data on early AF identification in relation to thyroid function are scarce. Even though symptomatic AF is rare in patients with thyroid malignancies, who are under thyroid suppressive therapy, clinicians should be aware of potential interaction with asymptomatic AF. It may prevent adverse consequences and improve the quality of life. This issue may be challenging for an updated registry of AF in clinical practice. Thyroid hormones should be considered a biomarker for cardiac arrhythmias screening and their tailored management because of their multifaceted cellular actions.
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Affiliation(s)
- Narcis Tribulova
- Centre of Experimental Medicine, Slovak Academy of Sciences, Institute for Heart Research, 84104 Bratislava, Slovakia
| | - Lin Hai Kurahara
- Department of Cardiovascular Physiology, Faculty of Medicine, Kagawa University, Kagawa 76 0793, Japan; (L.H.K.); (K.H.)
| | - Peter Hlivak
- Department of Arrhythmias and Pacing, National Institute of Cardiovascular Diseases, Pod Krásnou Hôrkou 1, 83348 Bratislava, Slovakia;
| | - Katsuya Hirano
- Department of Cardiovascular Physiology, Faculty of Medicine, Kagawa University, Kagawa 76 0793, Japan; (L.H.K.); (K.H.)
| | - Barbara Szeiffova Bacova
- Centre of Experimental Medicine, Slovak Academy of Sciences, Institute for Heart Research, 84104 Bratislava, Slovakia
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7
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Imbalance of cardiac autonomic nervous activity and increase of ventricular repolarization dynamicity induced by thyroid hormones in hyperthyroidism. Auton Neurosci 2018; 213:86-91. [DOI: 10.1016/j.autneu.2018.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 06/26/2018] [Accepted: 06/26/2018] [Indexed: 01/15/2023]
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Abstract
RATIONALE Dome-and-dart T waves (or bifid T waves) are a rare phenomenon in the surface electrocardiogram. These wave forms are mainly observed in patients with congenital heart disease such as atrial septal defect and ventricular septal defect. And hyperthyroidism who presented with an electrocardiogram that had dome-and-dart T waves in a precordial lead is never been reported. PATIENT CONCERNS The patient presented with continuous tachycardia, palpitations, chest tightness, and headache for 4 days, and aggravated for 1 day. DIAGNOSES Hyperthyroidism. INTERVENTIONS Methimazole. OUTCOMES All symptoms were alleviated. LESSONS Dome-and-dart or bifid T waves have been reported in the conventional 12-lead electrocardiograms in some patients with congenital heart disease. The case illustrated here, to the best of our knowledge, dome-and-dart or bifid T waves may associate with hyperthyroidism patients.
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Affiliation(s)
- Ping Lai
- Gannan Medical University, Ganzhou
| | | | - Jin-hua Xue
- Department of Pathophysiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou
- Department of Physiology, School of Basic Medical Sciences, Gannan Medical University
| | - Yue-qun Qiu
- Department of Cardiology, Ganzhou Cardiology Center, Society for Cardiovascular Internal Medicine, Emergency Medicine, the First Affiliated Hospital of Gannan Medical University, Ganzhou, China
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9
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Thyroid hormones and cardiac arrhythmias. Vascul Pharmacol 2009; 52:102-12. [PMID: 19850152 DOI: 10.1016/j.vph.2009.10.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 10/05/2009] [Indexed: 01/09/2023]
Abstract
Thyroid hormone plays an important role in cardiac electrophysiology and Ca2+ handling through both genomic and nongenomic mechanisms of action, while both actions can interfere. Chronic changes in the amount of circulating thyroid hormone due to thyroid dysfunction or systemic disease result in structural, electrophysiological and Ca2+ handling remodeling, while acute changes may affect basal activity of cardiac cells membrane systems. Consequently, long-term or rapid modulation of sarcolemmal ion channels, Ca2+ cycling proteins and intercellular communicating channels by thyroid hormone may affect heart function as well as susceptibility of the heart to arrhythmias. This aspect including pro- and anti-arrhythmic potential of thyroid hormone is highlighted in this review.
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Yu Z, Huang CX, Wang SY, Wang T, Xu L. Thyroid hormone predisposes rabbits to atrial arrhythmias by shortening monophasic action period and effective refractory period: results from an in vivo study. J Endocrinol Invest 2009; 32:253-7. [PMID: 19542744 DOI: 10.1007/bf03346462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Atrial arrhythmias are common complications of hyperthyroidism, but the underlying mechanisms remain to be further clarified. Thus, in this study, we try to investigate the effects of thyroid hormone on atrial electrophysiology by using a hyperthyroidism model in vivo. MATERIALS AND METHODS Twenty-four New Zealand white rabbits were randomized into Thyroxine group (no.=12) and Control group (no.=12). In Thyroxine group, Levo-thyroxine (L-T(4)) solution (1 mg/kg x d(-1)) was injected daily into the peritoneum for 2 weeks. In Control group, the same amount of saline was injected. On day 15, 8 rabbits in each group were chosen randomly to receive electrophysiological experiment in vivo, in which electrophysiological parameters and atrial arrhythmias induced by electrical stimulation were recorded and serum thyroid hormone levels were examined. The others were killed so as to exam the L-type calcium current of atrium. RESULTS Atrial monophasic action potential at 90 repolarization (AMAP(90)) and effective refractory period (AERP) were significantly shorter in Thyroxine group than in Control group (AMAP(90): 103.21+/-1.94 vs 122.14+/-6.13, p<0.01; AERP: 82.69+/-0.99 vs 102.46+/-2.32, p<0.01). There are significant differences in the incidence of atrial arrhythmias between the two groups. The mean peak of L-type calcium current (I(Ca,L)) densities (pA/pF) at -10mV was significantly higher in Thyroxine group than in Control group (-8.59+/-0.68 vs -6.54+/-0.49, no.=8, p<0.001). CONCLUSIONS In our hyperthyroidism model, thyroid hormone predisposed rabbits to atrial arrhythmias by shortening AMAP and AERP, which might be associated with increased I(Ca,L) current densities in atrium.
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Affiliation(s)
- Z Yu
- Department of Cardiology, Renmin Hospital, Wuhan University, Wuhan, China
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11
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Almeida NAS, Cordeiro A, Machado DS, Souza LL, Ortiga-Carvalho TM, Campos-de-Carvalho AC, Wondisford FE, Pazos-Moura CC. Connexin40 messenger ribonucleic acid is positively regulated by thyroid hormone (TH) acting in cardiac atria via the TH receptor. Endocrinology 2009; 150:546-554. [PMID: 18787025 DOI: 10.1210/en.2008-0451] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Thyroid hormone (TH) regulates many cardiac genes via nuclear thyroid receptors, and hyperthyroidism is frequently associated with atrial fibrillation. Electrical activity propagation in myocardium depends on the transfer of current at gap junctions, and connexins (Cxs) 40 and 43 are the predominant junction proteins. In mice, Cx40, the main Cx involved in atrial conduction, is restricted to the atria and fibers of the conduction system, which also express Cx43. We studied cardiac expression of Cx40 and Cx43 in conjunction with electrocardiogram studies in mice overexpressing the dominant negative mutant thyroid hormone receptor-beta Delta337T exclusively in cardiomyocytes [myosin heavy chain (MHC-mutant)]. These mice develop the cardiac hypothyroid phenotype in the presence of normal serum TH. Expression was also examined in wild-type mice rendered hypothyroid or hyperthyroid by pharmacological treatment. Atrial Cx40 mRNA and protein levels were decreased (85 and 55%, respectively; P < 0.001) in MHC-mt mice. Atrial and ventricular Cx43 mRNA levels were not significantly changed. Hypothyroid and hyperthyroid animals showed a 25% decrease and 40% increase, respectively, in Cx40 mRNA abundance. However, MHC-mt mice presented very low Cx40 mRNA expression regardless of whether they were made hypothyroid or hyperthyroid. Atrial depolarization velocity, as represented by P wave duration in electrocardiograms of unanesthetized mice, was extremely reduced in MHC-mt mice, and to a lesser extent also in hypothyroid mice (90 and 30% increase in P wave duration). In contrast, this measure was increased in hyperthyroid mice (19% decrease in P wave duration). Therefore, this study reveals for the first time that Cx40 mRNA is up-regulated by TH acting in cardiac atria via the TH receptor and that this may be one of the mechanisms contributing to atrial conduction alterations in thyroid dysfunctions.
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Affiliation(s)
- Norma A S Almeida
- Laboratório de Endocrinologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
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12
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Shimizu W, Matsuo K, Kokubo Y, Satomi K, Kurita T, Noda T, Nagaya N, Suyama K, Aihara N, Kamakura S, Inamoto N, Akahoshi M, Tomoike H. Sex Hormone and Gender Difference?Role of Testosterone on Male Predominance in Brugada Syndrome. J Cardiovasc Electrophysiol 2007; 18:415-21. [PMID: 17394456 DOI: 10.1111/j.1540-8167.2006.00743.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The clinical phenotype is 8 to 10 times more prevalent in males than in females in patients with Brugada syndrome. Brugada syndrome has been reported to be thinner than asymptomatic normal controls. We tested the hypothesis that higher testosterone level associated with lower visceral fat may relate to Brugada phenotype and male predominance. METHODS AND RESULTS We measured body-mass index (BMI), body fat percentage (BF%), and several hormonal levels, including testosterone, in 48 Brugada males and compared with those in 96 age-matched control males. Brugada males had significantly higher testosterone (631 +/- 176 vs 537 +/- 158 ng/dL; P = 0.002), serum sodium, potassium, and chloride levels than those in control males by univariate analysis, and even after adjusting for age, exercise, stress, smoking, and medication of hypertension, diabetes, and hyperlipidemia, whereas there were no significant differences in other sex and thyroid hormonal levels. Brugada males had significantly lower BMI (22.1 +/- 2.9 vs 24.6 +/- 2.6 kg/m(2); P < 0.001) and BF% (19.6 +/- 4.9 vs 23.1 +/- 4.7%; P < 0.001) than control males. Testosterone level was inversely correlated with BMI and BF% in both groups, even after adjusting for the confounding variables. Conditional logistic regression models analysis showed significant positive and inverse association between Brugada syndrome and hypertestosteronemia (OR:3.11, 95% CI:1.22-7.93, P = 0.017) and BMI (OR:0.72, 95% CI:0.61-0.85, P < 0.001), respectively. CONCLUSIONS Higher testosterone level associated with lower visceral fat may have a significant role in the Brugada phenotype and male predominance in Brugada syndrome.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Osaka, Japan.
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Yamakawa M, Sunagawa M, Shimabukuro M, Higa N, Takasu N, Kosugi T. Effect of sodium channel blocker, pilsicainide hydrochloride, on net inward current of atrial myocytes in thyroid hormone toxicosis rats. Thyroid 2005; 15:653-9. [PMID: 16053380 DOI: 10.1089/thy.2005.15.653] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To investigate effect of pilsicainide hydrochloride (pilsicainide) on electrocardiogram (ECG) signals and action potentials (APs) of atrial myocytes, levo-thyroxine (T4, 500 microg/kg body weight) was daily injected into peritoneal cavity of Sprague-Dawley rats for 14 days. T4-treatment significantly shortened RR interval, P wave, and QRS complex durations on ECG. Although pilsicainide did not affect the heart rate, P wave and corrected QT interval (QTc) was increased in T4-treated rats. AP recordings revealed that AP durations at 20%, 50%, and 90% repolarization were significantly shortened and maximal rate of rise (Max dV/dt) was significantly increased in T4-treated rat atrial cells. Pilsicainide significantly decreased AP amplitude (APA) and Max dV/dt in both control and T4-treated rat atrial cells. Concentration-inhibition study demonstrated that pilsicainide significantly inhibited net inward current of T4-treated rats at lower concentration (IC50 of 29.2 microg/mL) than that of control rats (133 microg/mL). In conclusion, pilsicainide could decrease the conduction velocity in T4-treated rat atrium by decreasing the Max dV/dt and net inward current, which could be a possible treatment of thyrotoxicosis-induced arrhythmia.
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Affiliation(s)
- Munesada Yamakawa
- Department of Endocrinology and Metabolism, University of the Ryukyus, Okinawa, Japan
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