1
|
Weiser-Bitoun I, Mori H, Nabeshima T, Tanaka N, Kudo D, Sasaki W, Narita M, Matsumoto K, Ikeda Y, Arai T, Nakano S, Sumitomo N, Senbonmatsu TA, Matsumoto K, Kato R, Morrell CH, Tsutsui K, Yaniv Y. Age-dependent contribution of intrinsic mechanisms to sinoatrial node function in humans. Sci Rep 2023; 13:18875. [PMID: 37914708 PMCID: PMC10620402 DOI: 10.1038/s41598-023-45101-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023] Open
Abstract
Average beat interval (BI) and beat interval variability (BIV) are primarily determined by mutual entrainment between the autonomic-nervous system (ANS) and intrinsic mechanisms that govern sinoatrial node (SAN) cell function. While basal heart rate is not affected by age in humans, age-dependent reductions in intrinsic heart rate have been documented even in so-called healthy individuals. The relative contributions of the ANS and intrinsic mechanisms to age-dependent deterioration of SAN function in humans are not clear. We recorded ECG on patients (n = 16 < 21 years and n = 23 41-78 years) in the basal state and after ANS blockade (propranolol and atropine) in the presence of propofol and dexmedetomidine anesthesia. Average BI and BIV were analyzed. A set of BIV features were tested to designated the "signatures" of the ANS and intrinsic mechanisms and also the anesthesia "signature". In young patients, the intrinsic mechanisms and ANS mainly contributed to long- and short-term BIV, respectively. In adults, both ANS and intrinsic mechanisms contributed to short-term BIV, while the latter also contributed to long-term BIV. Furthermore, anesthesia affected ANS function in young patients and both mechanisms in adult. The work also showed that intrinsic mechanism features can be calculated from BIs, without intervention.
Collapse
Affiliation(s)
- Ido Weiser-Bitoun
- Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Hitoshi Mori
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Taisuke Nabeshima
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Naomichi Tanaka
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Daisuke Kudo
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Wataru Sasaki
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Masataka Narita
- Saitama Medical University International Medical Center, Saitama, Japan
| | | | - Yoshifumi Ikeda
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Takahide Arai
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Shintaro Nakano
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Naokata Sumitomo
- Saitama Medical University International Medical Center, Saitama, Japan
| | | | - Kazuo Matsumoto
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Ritsushi Kato
- Saitama Medical University International Medical Center, Saitama, Japan
| | - Christopher H Morrell
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Kenta Tsutsui
- Saitama Medical University International Medical Center, Saitama, Japan.
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Saitama, Japan.
| | - Yael Yaniv
- Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
- Laboratory of Bioenergetic and Bioelectric Systems, The Faculty of Biomedical Engineering Technion-IIT, Haifa, Israel.
| |
Collapse
|
2
|
Verkerk AO, Wilders R. Human Sinoatrial Node Pacemaker Activity: Role of the Slow Component of the Delayed Rectifier K + Current, I Ks. Int J Mol Sci 2023; 24:7264. [PMID: 37108427 PMCID: PMC10138838 DOI: 10.3390/ijms24087264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
The pacemaker activity of the sinoatrial node (SAN) has been studied extensively in animal species but is virtually unexplored in humans. Here we assess the role of the slowly activating component of the delayed rectifier K+ current (IKs) in human SAN pacemaker activity and its dependence on heart rate and β-adrenergic stimulation. HEK-293 cells were transiently transfected with wild-type KCNQ1 and KCNE1 cDNA, encoding the α- and β-subunits of the IKs channel, respectively. KCNQ1/KCNE1 currents were recorded both during a traditional voltage clamp and during an action potential (AP) clamp with human SAN-like APs. Forskolin (10 µmol/L) was used to increase the intracellular cAMP level, thus mimicking β-adrenergic stimulation. The experimentally observed effects were evaluated in the Fabbri-Severi computer model of an isolated human SAN cell. Transfected HEK-293 cells displayed large IKs-like outward currents in response to depolarizing voltage clamp steps. Forskolin significantly increased the current density and significantly shifted the half-maximal activation voltage towards more negative potentials. Furthermore, forskolin significantly accelerated activation without affecting the rate of deactivation. During an AP clamp, the KCNQ1/KCNE1 current was substantial during the AP phase, but relatively small during diastolic depolarization. In the presence of forskolin, the KCNQ1/KCNE1 current during both the AP phase and diastolic depolarization increased, resulting in a clearly active KCNQ1/KCNE1 current during diastolic depolarization, particularly at shorter cycle lengths. Computer simulations demonstrated that IKs reduces the intrinsic beating rate through its slowing effect on diastolic depolarization at all levels of autonomic tone and that gain-of-function mutations in KCNQ1 may exert a marked bradycardic effect during vagal tone. In conclusion, IKs is active during human SAN pacemaker activity and has a strong dependence on heart rate and cAMP level, with a prominent role at all levels of autonomic tone.
Collapse
Affiliation(s)
- Arie O. Verkerk
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
- Department of Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
| |
Collapse
|
3
|
Ricci E, Bartolucci C, Severi S. The virtual sinoatrial node: What did computational models tell us about cardiac pacemaking? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 177:55-79. [PMID: 36374743 DOI: 10.1016/j.pbiomolbio.2022.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022]
Abstract
Since its discovery, the sinoatrial node (SAN) has represented a fascinating and complex matter of research. Despite over a century of discoveries, a full comprehension of pacemaking has still to be achieved. Experiments often produced conflicting evidence that was used either in support or against alternative theories, originating intense debates. In this context, mathematical descriptions of the phenomena underlying the heartbeat have grown in importance in the last decades since they helped in gaining insights where experimental evaluation could not reach. This review presents the most updated SAN computational models and discusses their contribution to our understanding of cardiac pacemaking. Electrophysiological, structural and pathological aspects - as well as the autonomic control over the SAN - are taken into consideration to reach a holistic view of SAN activity.
Collapse
Affiliation(s)
- Eugenio Ricci
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Cesena (FC), Italy
| | - Chiara Bartolucci
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Cesena (FC), Italy
| | - Stefano Severi
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Cesena (FC), Italy.
| |
Collapse
|
4
|
The Effect of the Tongyang Huoxue Recipe (TYHX) on the I to/ I Kur in Ischemia/Reperfusion Sinoatrial Node Cells. Cardiovasc Ther 2022; 2022:4114817. [PMID: 36605374 PMCID: PMC9794430 DOI: 10.1155/2022/4114817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 09/26/2022] [Accepted: 11/23/2022] [Indexed: 12/24/2022] Open
Abstract
Background The transient outward potassium current (I to) and the ultrarapid delayed rectifier potassium current (I Kur) are major potassium currents involved in the repolarization process of sinoatrial node cells (SNCs). Methods and Results The SNCs of neonatal rats were divided into control, ischemia/reperfusion (I/R), I/R+blank serum, and Tongyang Huoxue recipe (TYHX) serum groups. I to and I Kur were recorded using the whole cell patch-clamp technique, and the current-voltage (I-V), steady-state activation (SSA), steady-state inactivation (SSI), and recovery from inactivation (RFI) curves were plotted, respectively. Compared to the control group, both the peak current density and the current density at the voltage of I to and I Kur decreased obviously in SNCs after simulated I/R, the SSA curves moved right, and the SSI curves moved left. After TYHX was added to the extracellular solution of SNCs, both the peak current density and the current density at the voltage of I to and I Kur increased significantly, the SSA curves moved left, and the SSI curves moved right with a significant difference of V 1/2. The recovery from the I Kur RFI curves was slightly restored, and the I to curves did not change. Conclusions TYHX increases the peak current density, accelerates the activation, and decreases the inactivation of the I to and I Kur. This may be the mechanism of TYHX in shortening the action potential duration of repolarization, which accelerates spontaneous pulsation.
Collapse
|
5
|
SHOX2 refines the identification of human sinoatrial nodal cell population in the in vitro cardiac differentiation. Regen Ther 2022; 21:239-249. [PMID: 36092505 PMCID: PMC9420958 DOI: 10.1016/j.reth.2022.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 06/22/2022] [Accepted: 07/23/2022] [Indexed: 12/02/2022] Open
Abstract
Introduction Dysfunction of the sinoatrial node (SAN) cells causes arrhythmias, and many patients require artificial cardiac pacemaker implantation. However, the mechanism of impaired SAN automaticity remains unknown, and the generation of human SAN cells in vitro may provide a platform for understanding the pathogenesis of SAN dysfunction. The short stature homeobox 2 (SHOX2) and hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (HCN4) genes are specifically expressed in SAN cells and are important for SAN development and automaticity. In this study, we aimed to purify and characterize human SAN-like cells in vitro, using HCN4 and SHOX2 as SAN markers. Methods We developed an HCN4-EGFP/SHOX2-mCherry dual reporter cell line derived from human induced pluripotent stem cells (hiPSCs), and HCN4 and SHOX2 gene expressions were visualized using the fluorescent proteins EGFP and mCherry, respectively. The dual reporter cell line was established using an HCN4-EGFP bacterial artificial chromosome-based semi-knock-in system and a CRISPR-Cas9-dependent knock-in system with a SHOX2-mCherry targeting vector. Flow cytometry, RT-PCR, and whole-cell patch-clamp analyses were performed to identify SAN-like cells. Results Flow cytometry analysis and cell sorting isolated HCN4-EGFP single-positive (HCN4+/SHOX2-) and HCN4-EGFP/SHOX2-mCherry double-positive (HCN4+/SHOX2+) cells. RT-PCR analyses showed that SAN-related genes were enriched within the HCN4+/SHOX2+ cells. Further, electrophysiological analyses showed that approximately 70% of the HCN4+/SHOX2+ cells exhibited SAN-like electrophysiological characteristics, as defined by the action potential parameters of the maximum upstroke velocity and action potential duration. Conclusions The HCN4-EGFP/SHOX2-mCherry dual reporter hiPSC system developed in this study enabled the enrichment of SAN-like cells within a mixed HCN4+/SHOX2+ population of differentiating cardiac cells. This novel cell line is useful for the further enrichment of human SAN-like cells. It may contribute to regenerative medicine, for example, biological pacemakers, as well as testing for cardiotoxic and chronotropic actions of novel drug candidates.
Collapse
|
6
|
Reali P, Piazza C, Tacchino G, Songia L, Nazzari S, Reni G, Frigerio A, Bianchi AM. Assessing stress variations in children during the strange situation procedure: comparison of three widely used respiratory sinus arrhythmia estimation methods. Physiol Meas 2021; 42. [PMID: 34325412 DOI: 10.1088/1361-6579/ac18ff] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/29/2021] [Indexed: 01/01/2023]
Abstract
Objective.The respiratory sinus arrhythmia (RSA) is a well-known marker of vagal activity that can be exploited to measure stress changes. RSA is usually estimated from heart rate variability (HRV). This study aims to compare the RSA obtained with three widely adopted methods showing their strengths and potential pitfalls.Approach.The three methods are tested on 69 healthy preschoolers undergoing a stressful protocol, the strange situation procedure (SSP). We compare the RSA estimated by the Porges method, the univariate autoregressive (AR) spectral analysis of the HRV signal, and the bivariate AR spectral analysis of HRV and respirogram signals. We examine RSA differences detected across the SSP episodes and correlation between the estimates provided by each method.Main results.The Porges and the bivariate AR approaches both detected significant differences (i.e. stress variations) in the RSA measured across the SSP. However, the latter method showed higher sensitivity to stress changes induced by the procedure, with the mean RSA variation between baseline and first separation from the mother (the most stressful condition) being significantly different among methods: Porges, -17.5%; univariate AR, -18.3%; bivariate AR, -23.7%. Moreover, the performances of the Porges algorithm were found strictly dependent on the applied preprocessing.Significance.Our findings confirm the bivariate AR analysis of the HRV and respiratory signals as a robust stress assessment tool that does not require any population-specific preprocessing of the signals and warn about using RSA estimates that neglect breath information in more natural experiments, such as those involving children, in which respiratory frequency changes are extremely likely.
Collapse
Affiliation(s)
- Pierluigi Reali
- Electronics Information and Bioengineering Department, Politecnico di Milano, Milano, Italy
| | - Caterina Piazza
- Bioengineering Laboratory, Scientific Institute IRCCS E. Medea, Bosisio Parini, LC, Italy
| | - Giulia Tacchino
- Electronics Information and Bioengineering Department, Politecnico di Milano, Milano, Italy
| | - Letizia Songia
- Electronics Information and Bioengineering Department, Politecnico di Milano, Milano, Italy
| | - Sarah Nazzari
- Child Psychopathology Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, LC, Italy
| | - Gianluigi Reni
- Bioengineering Laboratory, Scientific Institute IRCCS E. Medea, Bosisio Parini, LC, Italy
| | - Alessandra Frigerio
- Child Psychopathology Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, LC, Italy
| | - Anna Maria Bianchi
- Electronics Information and Bioengineering Department, Politecnico di Milano, Milano, Italy
| |
Collapse
|
7
|
Deficiency of CXXC finger protein 1 leads to small changes in heart rate but moderate epigenetic alterations and significant protein downregulation of hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) ion channels in mice. Heart Rhythm 2021; 18:1780-1789. [PMID: 34182171 DOI: 10.1016/j.hrthm.2021.06.1190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 06/09/2021] [Accepted: 06/17/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND The normal cardiac rhythm is generated in the sinoatrial node (SAN). Changes in ionic currents of the SAN may cause sinus arrhythmia. CXXC finger protein 1 (Cfp1) is an epigenetic regulator that is involved in transcriptional regulation of multiple genes. OBJECTIVE The purpose of this study was to explore whether Cfp1 controls SAN function through regulation of ion channel-related genes. METHODS Electrophysiological study, patch clamp recording, reverse transcriptase polymerase chain reaction, optical mapping, chromatin immunoprecipitation, and immunofluorescence staining were performed to evaluate the function of SAN and underlying mechanism on Cfp1 heterozygous knockout (Cfp1+/-) mice. RESULTS Heart rate was slower slightly and SAN recovery time was longer in Cfp1+/- mice than controls. Whole-cell patch-clamp recording showed that the firing rate of action potentials was reduced in Cfp1+/- mice. The density of If current was reduced by 66% in SAN cells of Cfp1+/- mice but the densities of ICa, ICa-L, and ICa-T were not changed. The hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) mRNA level in SAN tissue of Cfp1+/- mice was reduced. The HCN4 protein was significantly decreased in SAN cells and tissues after heterozygous deletion of Cfp1. Chromatin immunoprecipitation assay on cultured HL-1 cells demonstrated that Cfp1 was enriched in the promoter regions of HCN4. Knockdown of Cfp1 reduced H3K4 trimethylation, H3K9 acetylation, and H3K27 acetylation of HCN4 promoter region. CONCLUSION Deficiency of Cfp1 leads to small changes in heart rate by moderate epigenetic modification alterations and significant protein downregulation of HCN4 ion channels in mice.
Collapse
|
8
|
Interactions of Propofol With Human Voltage-gated Kv1.5 Channel Determined by Docking Simulation and Mutagenesis Analyses. J Cardiovasc Pharmacol 2018; 71:10-18. [DOI: 10.1097/fjc.0000000000000538] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|