1
|
Bychkov R, Juhaszova M, Calvo-Rubio Barrera M, Donald LAH, Coletta C, Shumaker C, Moorman K, Sirenko ST, Maltsev AV, Sollott SJ, Lakatta EG. The Heart's Pacemaker Mimics Brain Cytoarchitecture and Function: Novel Interstitial Cells Expose Complexity of the SAN. JACC Clin Electrophysiol 2022; 8:1191-1215. [PMID: 36182566 DOI: 10.1016/j.jacep.2022.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/27/2022] [Accepted: 07/01/2022] [Indexed: 10/14/2022]
Abstract
BACKGROUND The sinoatrial node (SAN) of the heart produces rhythmic action potentials, generated via calcium signaling within and among pacemaker cells. Our previous work has described the SAN as composed of a hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4)-expressing pacemaker cell meshwork, which merges with a network of connexin 43+/F-actin+ cells. It is also known that sympathetic and parasympathetic innervation create an autonomic plexus in the SAN that modulates heart rate and rhythm. However, the anatomical details of the interaction of this plexus with the pacemaker cell meshwork have yet to be described. OBJECTIVES This study sought to describe the 3-dimensional cytoarchitecture of the mouse SAN, including autonomic innervation, peripheral glial cells, and pacemaker cells. METHODS The cytoarchitecture of SAN whole-mount preparations was examined by three-dimensional confocal laser-scanning microscopy of triple immunolabeled with combinations of antibodies for HCN4, S100 calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), choline acetyltransferase, or vesicular acetylcholine transporter, and tyrosine hydroxylase, and transmission electron microscopy. RESULTS The SAN exhibited heterogeneous autonomic innervation, which was accompanied by a web of peripheral glial cells and a novel S100B+/GFAP- interstitial cell population, with a unique morphology and a distinct distribution pattern, creating complex interactions with other cell types in the node, particularly with HCN4-expressing cells. Transmission electron microscopy identified a similar population of interstitial cells as telocytes, which appeared to secrete vesicles toward pacemaker cells. Application of S100B to SAN preparations desynchronized Ca2+ signaling in HCN4-expressing cells and increased variability in SAN impulse rate and rhythm. CONCLUSIONS The autonomic plexus, peripheral glial cell web, and a novel S100B+/GFAP- interstitial cell type embedded within the HCN4+ cell meshwork increase the structural and functional complexity of the SAN and provide a new regulatory pathway of rhythmogenesis.
Collapse
Affiliation(s)
- Rostislav Bychkov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Miguel Calvo-Rubio Barrera
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Lorenzo A H Donald
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Christopher Coletta
- Laboratory of Genetics and Genomics, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Chad Shumaker
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Kayla Moorman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Alexander V Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA.
| |
Collapse
|
2
|
Sirenko ST, Zahanich I, Li Y, Lukyanenko YO, Lyashkov AE, Ziman BD, Tarasov KV, Younes A, Riordon DR, Tarasova YS, Yang D, Vinogradova TM, Maltsev VA, Lakatta EG. Phosphoprotein Phosphatase 1 but Not 2A Activity Modulates Coupled-Clock Mechanisms to Impact on Intrinsic Automaticity of Sinoatrial Nodal Pacemaker Cells. Cells 2021; 10:cells10113106. [PMID: 34831329 PMCID: PMC8623309 DOI: 10.3390/cells10113106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/02/2021] [Accepted: 11/05/2021] [Indexed: 12/02/2022] Open
Abstract
Spontaneous AP (action potential) firing of sinoatrial nodal cells (SANC) is critically dependent on protein kinase A (PKA) and Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent protein phosphorylation, which are required for the generation of spontaneous, diastolic local Ca2+ releases (LCRs). Although phosphoprotein phosphatases (PP) regulate protein phosphorylation, the expression level of PPs and phosphatase inhibitors in SANC and the impact of phosphatase inhibition on the spontaneous LCRs and other players of the oscillatory coupled-clock system is unknown. Here, we show that rabbit SANC express both PP1, PP2A, and endogenous PP inhibitors I-1 (PPI-1), dopamine and cyclic adenosine 3′,5′-monophosphate (cAMP)-regulated phosphoprotein (DARPP-32), kinase C-enhanced PP1 inhibitor (KEPI). Application of Calyculin A, (CyA), a PPs inhibitor, to intact, freshly isolated single SANC: (1) significantly increased phospholamban (PLB) phosphorylation (by 2–3-fold) at both CaMKII-dependent Thr17 and PKA-dependent Ser16 sites, in a time and concentration dependent manner; (2) increased ryanodine receptor (RyR) phosphorylation at the Ser2809 site; (3) substantially increased sarcoplasmic reticulum (SR) Ca2+ load; (4) augmented L-type Ca2+ current amplitude; (5) augmented LCR’s characteristics and decreased LCR period in intact and permeabilized SANC, and (6) increased the spontaneous basal AP firing rate. In contrast, the selective PP2A inhibitor okadaic acid (100 nmol/L) had no significant effect on spontaneous AP firing, LCR parameters, or PLB phosphorylation. Application of purified PP1 to permeabilized SANC suppressed LCR, whereas purified PP2A had no effect on LCR characteristics. Our numerical model simulations demonstrated that PP inhibition increases AP firing rate via a coupled-clock mechanism, including respective increases in the SR Ca2+ pumping rate, L-type Ca2+ current, and Na+/Ca2+-exchanger current. Thus, PP1 and its endogenous inhibitors modulate the basal spontaneous firing rate of cardiac pacemaker cells by suppressing SR Ca2+ cycling protein phosphorylation, the SR Ca2+ load and LCRs, and L-type Ca2+ current.
Collapse
|
3
|
Yang D, Morrell CH, Lyashkov AE, Tagirova Sirenko S, Zahanich I, Yaniv Y, Vinogradova TM, Ziman BD, Maltsev VA, Lakatta EG. Ca 2+ and Membrane Potential Transitions During Action Potentials Are Self-Similar to Each Other and to Variability of AP Firing Intervals Across the Broad Physiologic Range of AP Intervals During Autonomic Receptor Stimulation. Front Physiol 2021; 12:612770. [PMID: 34566668 PMCID: PMC8456031 DOI: 10.3389/fphys.2021.612770] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 06/02/2021] [Indexed: 12/02/2022] Open
Abstract
Ca2+ and V m transitions occurring throughout action potential (AP) cycles in sinoatrial nodal (SAN) cells are cues that (1) not only regulate activation states of molecules operating within criticality (Ca2+ domain) and limit-cycle (V m domain) mechanisms of a coupled-clock system that underlies SAN cell automaticity, (2) but are also regulated by the activation states of the clock molecules they regulate. In other terms, these cues are both causes and effects of clock molecular activation (recursion). Recently, we demonstrated that Ca2+ and V m transitions during AP cycles in single SAN cells isolated from mice, guinea pigs, rabbits, and humans are self-similar (obey a power law) and are also self-similar to trans-species AP firing intervals (APFIs) of these cells in vitro, to heart rate in vivo, and to body mass. Neurotransmitter stimulation of β-adrenergic receptor or cholinergic receptor-initiated signaling in SAN cells modulates their AP firing rate and rhythm by impacting on the degree to which SAN clocks couple to each other, creating the broad physiologic range of SAN cell mean APFIs and firing interval variabilities. Here we show that Ca2+ and V m domain kinetic transitions (time to AP ignition in diastole and 90% AP recovery) occurring within given AP, the mean APFIs, and APFI variabilities within the time series of APs in 230 individual SAN cells are self-similar (obey power laws). In other terms, these long-range correlations inform on self-similar distributions of order among SAN cells across the entire broad physiologic range of SAN APFIs, regardless of whether autonomic receptors of these cells are stimulated or not and regardless of the type (adrenergic or cholinergic) of autonomic receptor stimulation. These long-range correlations among distributions of Ca2+ and V m kinetic functions that regulate SAN cell clock coupling during each AP cycle in different individual, isolated SAN cells not in contact with each other. Our numerical model simulations further extended our perspectives to the molecular scale and demonstrated that many ion currents also behave self-similar across autonomic states. Thus, to ensure rapid flexibility of AP firing rates in response to different types and degrees of autonomic input, nature "did not reinvent molecular wheels within the coupled-clock system of pacemaker cells," but differentially engaged or scaled the kinetics of gears that regulate the rate and rhythm at which the "wheels spin" in a given autonomic input context.
Collapse
Affiliation(s)
- Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Christopher H. Morrell
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
- Department of Mathematics and Statistics, Loyola University Maryland, Baltimore, MD, United States
| | - Alexey E. Lyashkov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Ihor Zahanich
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion–Israel Institute of Technology, Haifa, Israel
| | - Tatiana M. Vinogradova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Bruce D. Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Victor A. Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| |
Collapse
|
4
|
Tagirova Sirenko S, Tsutsui K, Tarasov KV, Yang D, Wirth AN, Maltsev VA, Ziman BD, Yaniv Y, Lakatta EG. Self-Similar Synchronization of Calcium and Membrane Potential Transitions During Action Potential Cycles Predict Heart Rate Across Species. JACC Clin Electrophysiol 2021; 7:1331-1344. [PMID: 33933406 PMCID: PMC10089231 DOI: 10.1016/j.jacep.2021.02.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 01/23/2023]
Abstract
OBJECTIVES The purpose of this study was to discover regulatory universal mechanisms of normal automaticity in sinoatrial nodal (SAN) pacemaker cells that are self-similar across species. BACKGROUND Translation of knowledge of SAN automaticity gleaned from animal studies to human dysrhythmias (e.g., "sick sinus" syndrome [SSS]) requiring electronic pacemaker insertion has been suboptimal, largely because heart rate varies widely across species. METHODS Subcellular Ca2+ releases, whole cell action potential (AP)-induced Ca2+ transients, and APs were recorded in isolated mouse, guinea pig, rabbit, and human SAN cells. Ca2+-Vm kinetic parameters during phases of AP cycles from their ignition to recovery were quantified. RESULTS Although both action potential cycle lengths (APCLs) and Ca2+-Vm kinetic parameters during AP cycles differed across species by 10-fold, trans-species scaling of these during AP cycles and scaling of these to APCL in cells in vitro, electrocardiogram RR intervals in vivo, and body mass (BM) were self-similar (obeyed power laws) across species. Thus, APCL in vitro, heart rate in vivo, and BM of any species can be predicted by Ca2+-Vm kinetics during AP cycles in SAN cells measured in any single species in vitro. CONCLUSIONS In designing optimal heart rate to match widely different BM and energy requirements from mice to humans, nature did not "reinvent pacemaker cell wheels," but differentially scaled kinetics of gears that regulate the rates at which the "wheels spin." This discovery will facilitate the development of novel pharmacological and biological pacemakers featuring a normal, wide-range rate regulation in animal models and the translation of these to humans to target recalcitrant human SSS.
Collapse
Affiliation(s)
- Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA.
| | - Kenta Tsutsui
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA; Saitama International Medical Center, Saitama, Japan
| | - Kirill V Tarasov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA
| | - Ashley N Wirth
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA
| | - Bruce D Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA.
| |
Collapse
|
5
|
Vinogradova TM, Tagirova Sirenko S, Lakatta EG. Unique Ca 2+-Cycling Protein Abundance and Regulation Sustains Local Ca 2+ Releases and Spontaneous Firing of Rabbit Sinoatrial Node Cells. Int J Mol Sci 2018; 19:ijms19082173. [PMID: 30044420 PMCID: PMC6121616 DOI: 10.3390/ijms19082173] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/20/2018] [Accepted: 07/23/2018] [Indexed: 11/16/2022] Open
Abstract
Spontaneous beating of the heart pacemaker, the sinoatrial node, is generated by sinoatrial node cells (SANC) and caused by gradual change of the membrane potential called diastolic depolarization (DD). Submembrane local Ca2+ releases (LCR) from sarcoplasmic reticulum (SR) occur during late DD and activate an inward Na+/Ca2+ exchange current, which accelerates the DD rate leading to earlier occurrence of an action potential. A comparison of intrinsic SR Ca2+ cycling revealed that, at similar physiological Ca2+ concentrations, LCRs are large and rhythmic in permeabilized SANC, but small and random in permeabilized ventricular myocytes (VM). Permeabilized SANC spontaneously released more Ca2+ from SR than VM, despite comparable SR Ca2+ content in both cell types. In this review we discuss specific patterns of expression and distribution of SR Ca2+ cycling proteins (SR Ca2+ ATPase (SERCA2), phospholamban (PLB) and ryanodine receptors (RyR)) in SANC and ventricular myocytes. We link ability of SANC to generate larger and rhythmic LCRs with increased abundance of SERCA2, reduced abundance of the SERCA inhibitor PLB. In addition, an increase in intracellular [Ca2+] increases phosphorylation of both PLB and RyR exclusively in SANC. The differences in SR Ca2+ cycling protein expression between SANC and VM provide insights into diverse regulation of intrinsic SR Ca2+ cycling that drives automaticity of SANC.
Collapse
Affiliation(s)
- Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
| | - Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
| |
Collapse
|