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Filatova TS, Dzhumaniiazova I, Abramochkin DV. The metamorphosis of amphibian myocardium: moving to the heart of the matter. J Exp Biol 2024; 227:jeb247712. [PMID: 38916053 DOI: 10.1242/jeb.247712] [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: 03/08/2024] [Accepted: 04/26/2024] [Indexed: 06/26/2024]
Abstract
Amphibians are a classical object for physiological studies, and they are of great value for developmental studies owing to their transition from an aquatic larval form to an adult form with a terrestrial lifestyle. Axolotls (Ambystoma mexicanum) are of special interest for such studies because of their neoteny and facultative pedomorphosis, as in these animals, metamorphosis can be induced and fully controlled in laboratory conditions. It has been suggested that their metamorphosis, associated with gross anatomical changes in the heart, also involves physiological and electrical remodeling of the myocardium. We used whole-cell patch clamp to investigate possible changes caused by metamorphosis in electrical activity and major ionic currents in cardiomyocytes isolated from paedomorphic and metamorphic axolotls. T4-induced metamorphosis caused shortening of atrial and ventricular action potentials (APs), with no changes in resting membrane potential or maximum velocity of AP upstroke, favoring higher heart rate possible in metamorphic animals. Potential-dependent potassium currents in axolotl myocardium were represented by delayed rectifier currents IKr and IKs, and upregulation of IKs caused by metamorphosis probably underlies AP shortening. Metamorphosis was associated with downregulation of inward rectifier current IK1, probably serving to increase the excitability of myocardium in metamorphic animals. Metamorphosis also led to a slight increase in fast sodium current INa with no changes in its steady-state kinetics and to a significant upregulation of ICa in both atrial and ventricular cells, indicating stronger Ca2+ influx for higher cardiac contractility in metamorphic salamanders. Taken together, these changes serve to increase cardiac reserve in metamorphic animals.
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Affiliation(s)
- Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Irina Dzhumaniiazova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
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Abramochkin DV, Shamshura A, Dzhumaniiazova I, Pustovit OB, Mishchenko AA. High temperature and hyperkalemia increase vulnerability of navaga cod (Eleginus nawaga) cardiomyocytes to the ecotoxicant 3-methyl-phenanthrene. Comp Biochem Physiol A Mol Integr Physiol 2024:111761. [PMID: 39369815 DOI: 10.1016/j.cbpa.2024.111761] [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: 06/29/2024] [Revised: 09/16/2024] [Accepted: 10/03/2024] [Indexed: 10/08/2024]
Abstract
Oil and gas mining and transportation in the Arctic can lead to release of polycyclic aromatic hydrocarbons (PAHs) in the ocean and freshwater basins. PAHs are known for their toxic effects in fish hearts, including the inhibition of main ionic currents (IKr, INa and ICaL) in fish cardiac myocytes. The present study is the first one to assess the effect of a particular PAH abundant in crude oil and diesel, namely 3-methyl-phenanthrene (3-MP), on the electrical excitability (EE) of cardiomyocytes from navaga cod (Eleginus nawaga), commercial fish species from the Arctic. Action potentials (APs) were elicited in current-clamp experiments at 9, 15 and 21 °C, and AP characteristics and the current needed to elicit APs were examined. Also, the effects of 3 μM 3-MP were tested at 3 temperatures and in normal (3.5 mM) and high (8 mM) extracellular K+ concentrations. Elevation of temperature leads to hyperpolarization of resting membrane potential and AP shortening, but does not decrease EE. 3-MP was found to suppress EE in cardiomyocytes at 9 and 15 °C, but not at 21 °C. High extracellular K+ itself drastically decreases EE, although it does not worsen the effect of 3-MP. However, combination of hyperthermia and high K+ leads to augmentation of depressive effect of 3-MP on EE. We hypothesize that hyperthermia rescues Na+ channels from inactivation due to membrane hyperpolarization, thereby compensating for the partial inhibition of INa by 3-MP. However, elevation of extracellular K+ nullifies this protective mechanism by depolarizing the resting potential and aggravates the effect of 3-MP.
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Affiliation(s)
- Denis V Abramochkin
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China; Department of human and animal physiology, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia; Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Artem Shamshura
- Department of human and animal physiology, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
| | - Irina Dzhumaniiazova
- Department of human and animal physiology, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
| | - Oksana B Pustovit
- Department of human and animal physiology, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
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Lopez JR, Linares N, Adams JA, Mijares A. The Role of the Na+/Ca2+ Exchanger in Aberrant Intracellular Ca2+ in Cardiomyocytes of Chagas-Infected Rodents. Front Cell Infect Microbiol 2022; 12:890709. [PMID: 35903196 PMCID: PMC9318578 DOI: 10.3389/fcimb.2022.890709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 06/03/2022] [Indexed: 11/28/2022] Open
Abstract
Chagas disease is produced by the parasite Trypanosoma cruzi (T. cruzi), which is the leading cause of death and morbidity in Latin America. We have shown that in patients with Chagas cardiomyopathy, there is a chronic elevation of diastolic Ca2+ concentration ([Ca2+]d), associated with deterioration to further address this issue, we explored the role Na+/Ca2+ exchanger (NCX). Experiments were carried out in noninfected C57BL/6 mice and infected with blood-derived trypomastigotes of the T. cruzi Y strain. Anesthetized mice were sacrificed and the cardiomyocytes were enzymatically dissociated. Diastolic [Ca2+] ([Ca2+]d) was measured using Ca2+ selective microelectrodes in cardiomyocytes from control mice (CONT) and cardiomyocytes from T. cruzi infected mice in the early acute phase (EAP) at 20 dpi, in the acute phase (AP) at 40 dpi, and in the chronic phase (CP) at 120 dpi. [Ca2+]d was 1.5-times higher in EAP, 2.6-times in AP, and 3.4-times in CP compared to CONT. Exploring the reverse mode activity of NCX, we replaced extracellular Na+ in equivalent amounts with N-methyl-D-glucamine. Reduction of [Na+]e to 65 mM caused an increase in [Ca2+]d of 1.7 times in cardiomyocytes from CONT mice, 2 times in EAP infected mice, 2.4 times in AP infected mice and 2.8 in CP infected mice. The Na+ free solution caused a further elevation of [Ca2+]d of 2.5 times in cardiomyocytes from CONT, 2.8 times in EAP infected mice, 3.1 times in AP infected mice, and 3.3 times in CP infected mice. Extracellular Ca2+ withdrawal reduced [Ca2+]d in both CONT and cardiomyocytes from Chagas-infected mice and prevented the increase in [Ca2+]d induced by Na+ depletion. Preincubation with 10µM KB-R7943 or in 1µM YM-244769 reduced [Ca2+]d in cardiomyocytes from infected mice, but not control mice. Furthermore, both NCX blockers prevented the increase in [Ca2+]d associated with exposure to a solution without Na+. These results suggest that Ca2+ entry through the reverse NCX mode plays a significant role in the observed [Ca2+]d dyshomeostasis in Chagas infected cardiomyocytes. Additionally, NCX inhibitors may be a viable therapeutic approach for treating patients with Chagas cardiomyopathy.
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Affiliation(s)
- Jose R. Lopez
- Department of Research, Mount Sinai, Medical Center, Miami, FL, United States
| | - Nancy Linares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Jose A. Adams
- Division of Neonatology, Mount Sinai, Medical Center, Miami, FL, United States
| | - Alfredo Mijares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
- *Correspondence: Alfredo Mijares,
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Abramochkin DV, Filatova TS, Pustovit KB, Voronina YA, Kuzmin VS, Vornanen M. Ionic currents underlying different patterns of electrical activity in working cardiac myocytes of mammals and non-mammalian vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2022; 268:111204. [PMID: 35346823 DOI: 10.1016/j.cbpa.2022.111204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 12/19/2022]
Abstract
The orderly contraction of the vertebrate heart is determined by generation and propagation of cardiac action potentials (APs). APs are generated by the integrated activity of time- and voltage-dependent ionic channels which carry inward Na+ and Ca2+ currents, and outward K+ currents. This review compares atrial and ventricular APs and underlying ion currents between different taxa of vertebrates. We have collected literature data and attempted to find common electrophysiological features for two or more vertebrate groups, show differences between taxa and cardiac chambers, and indicate gaps in the existing data. Although electrical excitability of the heart in all vertebrates is based on the same superfamily of channels, there is a vast variability of AP waveforms between atrial and ventricular myocytes, between different species of the same vertebrate class and between endothermic and ectothermic animals. The wide variability of AP shapes is related to species-specific differences in animal size, heart rate, stage of ontogenetic development, excitation-contraction coupling, temperature and oxygen availability. Some of the differences between taxa are related to evolutionary development of genomes, which appear e.g. in the expression of different Na+ and K+ channel orthologues in cardiomyocytes of vertebrates. There is a wonderful variability of AP shapes and underlying ion currents with which electrical excitability of vertebrate heart can be generated depending on the intrinsic and extrinsic conditions of animal body. This multitude of ionic mechanisms provides excellent material for studying how the function of the vertebrate heart can adapt or acclimate to prevailing physiological and environmental conditions.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia.
| | - Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Ksenia B Pustovit
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Yana A Voronina
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, 3(rd) Cherepkovskaya str., 15A, Moscow, Russia
| | - Vladislav S Kuzmin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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Tapilina SV, Ivanova AD, Filatova TS, Galenko-Yaroshevsky PA, Abramochkin DV. The role of M3 receptors in regulation of electrical activity deteriorates in the rat heart during ageing. Curr Res Physiol 2022; 5:1-7. [PMID: 34977599 PMCID: PMC8685909 DOI: 10.1016/j.crphys.2021.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/25/2021] [Accepted: 12/02/2021] [Indexed: 11/29/2022] Open
Abstract
Ageing is a complex process which affects all systems of the organism and therefore changes the environment where the heart is working. In this study we demonstrate the ageing-related changes in the mechanisms of parasympathetic regulation of mammalian heart. Electrophysiological effects produced by selective activation of M3-cholinoreceptors were compared in isolated cardiac preparations from young adult (4 months), adult (1 year) and ageing (2 years) rats using sharp glass microelectrode technique. M3-receptors were activated with muscarinic agonist pilocarpine (10-5M) in the presence of selective M2 antagonist AQ-RA741 (10-7M). In atrial and ventricular myocardium from young rats M3 stimulation induced shortening of action potentials(APs), while no significant effect was observed in both elder groups. The main mechanism of M3-induced AP shortening is inhibition of L-type Ca2+ current, estimated using whole-cell patch-clamp. It was negligible in atrial myocytes from ageing animals in comparison with young rats. The loss of sensitivity to stimulation of M3-receptors is due to decrease in M3 gene expression, shown by RT-PCR both in atrial and ventricular samples from ageing rats. Thus, in ageing rat heart M3-receptors are down-regulated and not involved in regulation of electrical activity. Stimulation of M3-receptors shortens action potentials (APs) in rat myocardium. This effect of M3-stimulation is diminished in 1 and 2-year old rats. Underlying M3-mediated inhibition of L-type Ca2+ current deteriorates in aged rats. These age-related changes are due to downregulation of M3 receptors.
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Affiliation(s)
- Svetlana V Tapilina
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory 1, 12, Moscow, Russia
| | - Alexandra D Ivanova
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory 1, 12, Moscow, Russia
| | - Tatiana S Filatova
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory 1, 12, Moscow, Russia.,Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova Str 1, Moscow, Russia.,Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, Moscow, Russia
| | | | - Denis V Abramochkin
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory 1, 12, Moscow, Russia
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Filatova TS, Abramochkin DV, Pavlova NS, Pustovit KB, Konovalova OP, Kuzmin VS, Dobrzynski H. Repolarizing potassium currents in working myocardium of Japanese quail: a novel translational model for cardiac electrophysiology. Comp Biochem Physiol A Mol Integr Physiol 2021; 255:110919. [DOI: 10.1016/j.cbpa.2021.110919] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/06/2021] [Accepted: 02/06/2021] [Indexed: 12/14/2022]
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Fat taste signal transduction and its possible negative modulator components. Prog Lipid Res 2020; 79:101035. [DOI: 10.1016/j.plipres.2020.101035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/26/2020] [Accepted: 04/29/2020] [Indexed: 02/07/2023]
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Zhabyeyev P, McLean B, Chen X, Vanhaesebroeck B, Oudit GY. Inhibition of PI3Kinase-α is pro-arrhythmic and associated with enhanced late Na + current, contractility, and Ca 2+ release in murine hearts. J Mol Cell Cardiol 2019; 132:98-109. [PMID: 31095940 DOI: 10.1016/j.yjmcc.2019.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/11/2019] [Accepted: 05/09/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Phosphoinositide 3-kinase α (PI3Kα) is a proto-oncogene with high activity in the heart. BYL719 (BYL) is a PI3Kα-selective small molecule inhibitor and a prospective drug for advanced solid tumors. We investigated whether acute pharmacological inhibition of PI3Kα has pro-arrhythmic effects. METHODS & RESULTS In isolated wild-type (WT) cardiomyocytes, pharmacological inhibition of PI3Kα (BYL719) increased contractility by 28%, Ca2+ release by 20%, and prolonged action potential (AP) repolarization by 10-15%. These effects of BYL719 were abolished by inhibition of reverse-mode Na+/Ca2+ exchanger (NCX) (KB-R7943) or by inhibition of late Na+ current (INa-L) (ranolazine). BYL719 had no effect on PI3Kα-deficient cardiomyocytes, suggesting BYL719 effects were PI3Kα-dependent and mediated via NCX and INa-L. INa-L was suppressed by activation of PI3Kα, application of exogenous intracellular PIP3, or ranolazine. Investigation of AP and Ca2+ release in whole heart preparations using epicardial optical mapping showed that inhibition of PI3Kα similarly led to prolongation of AP and enhancement of Ca2+ release. In hearts of PI3Kα-deficient mice, β-adrenergic stimulation in the presence of high Ca2+ concentrations and 12-Hz burst pacing led to delayed afterdepolarizations and ventricular fibrillation. In vivo, administration of BYL719 prolonged QT interval [QTcF (Fridericia) increased by 15%] in WT, but not in PI3Kα-deficient mice. CONCLUSIONS Pharmacological inhibition of PI3Kα is arrhythmogenic due to activation of INa-L leading to increased sarcoplasmic reticulum Ca2+ load and prolonged QT interval. Therefore, monitoring of cardiac electrical activity in patients receiving PI3K inhibitors may provide further insights into the arrhythmogenic potential of PI3Ka inhibition.
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Affiliation(s)
- Pavel Zhabyeyev
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Brent McLean
- Department of Medicine, University of Alberta, Edmonton, Canada; Department of Physiology, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Xueyi Chen
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | | | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada.
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Smolyaninova LV, Koltsova SV, Sidorenko SV, Orlov SN. Augmented gene expression triggered by Na + ,K + -ATPase inhibition: Role of Ca 2+ i -mediated and −independent excitation-transcription coupling. Cell Calcium 2017; 68:5-13. [DOI: 10.1016/j.ceca.2017.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/28/2017] [Accepted: 10/07/2017] [Indexed: 11/16/2022]
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Wu SN, Chern JH, Shen S, Chen HH, Hsu YT, Lee CC, Chan MH, Lai MC, Shie FS. Stimulatory actions of a novel thiourea derivative on large-conductance, calcium-activated potassium channels. J Cell Physiol 2017; 232:3409-3421. [PMID: 28075010 DOI: 10.1002/jcp.25788] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 01/14/2023]
Abstract
In this study, we examine whether an anti-inflammatory thiourea derivative, compound #326, actions on ion channels. The effects of compound #326 on Ca2+ -activated K+ channels were evaluated by patch-clamp recordings obtained in cell-attached, inside-out or whole-cell configuration. In pituitary GH3 cells, compound #326 increased the amplitude of Ca2+ -activated K+ currents (IK(Ca) ) with an EC50 value of 11.6 μM, which was reversed by verruculogen, but not tolbutamide or TRAM-34. Under inside-out configuration, a bath application of compound #326 raised the probability of large-conductance Ca2+ -activated K+ (BKCa ) channels. The activation curve of BKCa channels was shifted to less depolarised potential with no modification of the gating charge of the curve; consequently, the difference of free energy was reduced in the presence of this compound. Compound #326-stimulated activity of BKCa channels is explained by a shortening of mean closed time, despite its inability to alter single-channel conductance. Neither delayed-rectifier nor erg-mediated K+ currents was modified. Compound #326 decreased the peak amplitude of voltage-gated Na+ current with no clear change in the overall current-voltage relationship of this current. In HEK293T cells expressing α-hSlo, compound #326 enhanced BKCa channels effectively. Intriguingly, the inhibitory actions of compound #326 on interleukin 1β in lipopolysaccharide-activated microglia were significantly reversed by verruculogen, whereas BKCa channel inhibitors suppressed the expressions of inducible nitric oxide synthase. The BKCa channels could be an important target for compound #326 if similar in vivo results occur, and the multi-functionality of BKCa channels in modulating microglial immunity merit further investigation.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan City, Taiwan
| | - Jyh-Haur Chern
- Division of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Santai Shen
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Hwei-Hisen Chen
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Ying-Ting Hsu
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Chih-Chin Lee
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
| | - Ming-Huan Chan
- Institute of Neuroscience, National Chengchi University, Taipei City, Taiwan
| | - Ming-Chi Lai
- Department of Pediatrics, Chi Mei Medical Center, Tainan City, Taiwan
| | - Feng-Shiun Shie
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli County, Taiwan
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Li Y, Cheng KC, Niu CS, Lo SH, Cheng JT, Niu HS. Investigation of triamterene as an inhibitor of the TGR5 receptor: identification in cells and animals. DRUG DESIGN DEVELOPMENT AND THERAPY 2017; 11:1127-1134. [PMID: 28435224 PMCID: PMC5391213 DOI: 10.2147/dddt.s131892] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background G-protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) has been shown to participate in glucose homeostasis. In animal models, a TGR5 agonist increases incretin secretion to reduce hyperglycemia. Many agonists have been developed for clinical use. However, the effects of TGR5 blockade have not been studied extensively, with the exception of studies using TGR5 knockout mice. Therefore, we investigated the potential effect of triamterene on TGR5. Methods We transfected the TGR5 gene into cultured Chinese hamster ovary cells (CHO-K1 cells) to express TGR5. Then, we applied a fluorescent indicator to examine the glucose uptake of these transfected cells. In addition, NCI-H716 cells that secrete incretin were also evaluated. Fura-2, a fluorescence indicator, was applied to determine the changes in calcium concentrations. The levels of cyclic adenosine monophosphate (cAMP) and glucagon-like peptide (GLP-1) were estimated using enzyme-linked immunosorbent assay kits. Moreover, rats with streptozotocin (STZ)-induced type 1-like diabetes were used to investigate the effects in vivo. Results Triamterene dose dependently inhibits the increase in glucose uptake induced by TGR5 agonists in CHO-K1 cells expressing the TGR5 gene. In cultured NCI-H716 cells, TGR5 activation also increases GLP-1 secretion by increasing calcium levels. Triamterene inhibits the increased calcium levels by TGR5 activation through competitive antagonism. Moreover, the GLP-1 secretion and increased cAMP levels induced by TGR5 activation are both dose dependently reduced by triamterene. However, treatment with KB-R7943 at a dose sufficient to block the Na+/Ca2+ exchanger (NCX) failed to modify the responses to TGR5 activation in NCI-H716 cells or CHO-K1 cells expressing TGR5. Therefore, the inhibitory effects of triamterene on TGR5 activation do not appear to be related to NCX inhibition. Blockade of TGR5 activation by triamterene was further characterized in vivo using the STZ-induced diabetic rats. Conclusion Based on the obtained data, we identified triamterene as a reliable inhibitor of TGR5. Therefore, triamterene can be developed as a clinical inhibitor of TGR5 activation in future studies.
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Affiliation(s)
- Yingxiao Li
- Department of Psychosomatic Internal Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Medical Research, Chi Mei Medical Center, Yong Kang, Tainan City
| | - Kai Chun Cheng
- Department of Psychosomatic Internal Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Chiang-Shan Niu
- Department of Nursing, Tzu Chi University of Science and Technology, Hualien City
| | - Shih-Hsiang Lo
- Department of Nursing, Tzu Chi University of Science and Technology, Hualien City.,Division of Cardiology, Department of Internal Medicine, Chung Hsing Branch of Taipei City Hospital
| | - Juei-Tang Cheng
- Department of Medical Research, Chi Mei Medical Center, Yong Kang, Tainan City.,Institute of Medical Sciences, College of Health Science, Chang-Jung Christian University, Guei-Ren, Tainan City, Taiwan
| | - Ho-Shan Niu
- Department of Nursing, Tzu Chi University of Science and Technology, Hualien City
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Kazanski V, Mitrokhin VM, Mladenov MI, Kamkin AG. Cytokine Effects on Mechano-Induced Electrical Activity in Atrial Myocardium. Immunol Invest 2016; 46:22-37. [PMID: 27617892 DOI: 10.1080/08820139.2016.1208220] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The role of cytokines as regulators of stretch-related mechanisms is of special importance since mechano-sensitivity plays an important role in a wide variety of biological processes. Here, we elucidate the influence of cytokine application on mechano-sensitivity and mechano-transduction. The atrial myocardial stretch induces production of interleukin (IL)-2, IL-6, IL-13, IL-17A, and IL-18 with exception of tumor necrosis factor α (TNF-α), IL-1β, and vascular endothelial growth factor B (VEGF-B). Positive ionotropic effect was specific for VEGF-B, negative ionotropic effects were specific for TNF-α, IL-1β, IL-2, IL-6, IL-13, IL-17A and IL-18, while IL-1α doesn't show direct ionotropic effect. The IL-2, IL-6, IL-17A, IL-18, and VEGF-B cause elongation of the APD, in comparison with the reduced APD caused by the IL-13. The TNF-α, IL-1β, and IL-18 influences L-type Ca2+ channels, IL-2 has an inhibitory effect on the fast Na+ channels while IL-17A and VEGF-B were specific for Kir channels. With exception of the IL-1α, IL-2, and VEGF-B, all analyzed cytokines include nitric oxide dependent signaling with resultant combined effects on mechano-gated and Ca2+ channels. The relationships between these pathways and the time-dependence of their activation are of important considerations in the evaluation of cytokine-induced electrical abnormality, specific for cardiac dysfunctions. In general, the discussion presented in this review covers research devoted to counterbalance between different cytokines in the regulation of stretch-induced effects in rat atrial myocardium. ABBREVIATIONS APs: action potentials; APD25: action potential durations to 25% of re-polarization; APD50: action potential durations to 50% of repolarization; APD90: action potential durations to 90% of repolarization; MGCs: mechanically gated channels.
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Affiliation(s)
- V Kazanski
- a Department of Fundamental and Applied Physiology , Russian National Research Medical University , Moscow , Russia
| | - V M Mitrokhin
- a Department of Fundamental and Applied Physiology , Russian National Research Medical University , Moscow , Russia
| | - M I Mladenov
- a Department of Fundamental and Applied Physiology , Russian National Research Medical University , Moscow , Russia.,b Faculty of Natural Sciences and Mathematics, Institute of Biology , "Ss. Cyril and Methodius" University , Skopje , Macedonia
| | - A G Kamkin
- a Department of Fundamental and Applied Physiology , Russian National Research Medical University , Moscow , Russia
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La J, Reed EB, Koltsova S, Akimova O, Hamanaka RB, Mutlu GM, Orlov SN, Dulin NO. Regulation of myofibroblast differentiation by cardiac glycosides. Am J Physiol Lung Cell Mol Physiol 2016; 310:L815-23. [PMID: 26851261 DOI: 10.1152/ajplung.00322.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/02/2016] [Indexed: 11/22/2022] Open
Abstract
Myofibroblast differentiation is a key process in pathogenesis of fibrotic diseases. Cardiac glycosides (ouabain, digoxin) inhibit Na(+)-K(+)-ATPase, resulting in increased intracellular [Na(+)]-to-[K(+)] ratio in cells. Microarray analysis suggested that increased intracellular [Na(+)]/[K(+)] ratio may promote the expression of cyclooxygenase-2 (COX-2), a critical enzyme in the synthesis of prostaglandins. Given antifibrotic effects of prostaglandins through activation of protein kinase A (PKA), we examined if cardiac glycosides stimulate COX-2 expression in human lung fibroblasts and how they affect myofibroblast differentiation. Ouabain stimulated a profound COX-2 expression and a sustained PKA activation, which was blocked by COX-2 inhibitor or by COX-2 knockdown. Ouabain-induced COX-2 expression and PKA activation were abolished by the inhibitor of the Na(+)/Ca(2+) exchanger, KB-R4943. Ouabain inhibited transforming growth factor-β (TGF-β)-induced Rho activation, stress fiber formation, serum response factor activation, and the expression of smooth muscle α-actin, collagen-1, and fibronectin. These effects were recapitulated by an increase in intracellular [Na(+)]/[K(+)] ratio through the treatment of cells with K(+)-free medium or with digoxin. Although inhibition of COX-2 or of the Na(+)/Ca(2+) exchanger blocked ouabain-induced PKA activation, this failed to reverse the inhibition of TGF-β-induced Rho activation or myofibroblast differentiation by ouabain. Together, these data demonstrate that ouabain, through the increase in intracellular [Na(+)]/[K(+)] ratio, drives the induction of COX-2 expression and PKA activation, which is accompanied by a decreased Rho activation and myofibroblast differentiation in response to TGF-β. However, COX-2 expression and PKA activation are not sufficient for inhibition of the fibrotic effects of TGF-β by ouabain, suggesting that additional mechanisms must exist.
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Affiliation(s)
- Jennifer La
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, the University of Chicago, Chicago, Illinois
| | - Eleanor B Reed
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, the University of Chicago, Chicago, Illinois
| | - Svetlana Koltsova
- Laboratory of Biomembranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russian Federation; and
| | - Olga Akimova
- Laboratory of Biomembranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russian Federation; and
| | - Robert B Hamanaka
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, the University of Chicago, Chicago, Illinois
| | - Gökhan M Mutlu
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, the University of Chicago, Chicago, Illinois
| | - Sergei N Orlov
- Laboratory of Biomembranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russian Federation; and Siberian State Medical University, Tomsk, Russian Federation
| | - Nickolai O Dulin
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, the University of Chicago, Chicago, Illinois;
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14
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Kapoor N, Tran A, Kang J, Zhang R, Philipson KD, Goldhaber JI. Regulation of calcium clock-mediated pacemaking by inositol-1,4,5-trisphosphate receptors in mouse sinoatrial nodal cells. J Physiol 2015; 593:2649-63. [PMID: 25903031 DOI: 10.1113/jp270082] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/15/2015] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS Inositol-1,4,5-trisphosphate receptors (IP3 Rs) modulate pacemaking in embryonic heart, but their role in adult sinoatrial node (SAN) pacemaking is uncertain. We found that stimulation of IP3 Rs accelerates spontaneous pacing rate in isolated mouse SAN cells, whereas inhibition of IP3 Rs slows pacing. In atrial-specific sodium-calcium exchanger (NCX) knockout (KO) SAN cells, where the Ca(2+) clock is uncoupled from the membrane clock, IP3 R agonists and antagonists modulate the rate of spontaneous Ca(2+) waves, suggesting that IP3 R-mediated Ca(2+) release modulates the Ca(2+) clock. IP3 R modulation also regulates Ca(2+) spark parameters, a reflection of ryanodine receptor open probability, consistent with the effect of IP3 signalling on Ca(2+) clock frequency. Modulation of Ca(2+) clock frequency by IP3 signalling in NCX KO SAN cells demonstrates that the effect is independent of NCX. These findings support development of IP3 signalling modulators for regulation of heart rate, particularly in heart failure where IP3 Rs are upregulated. ABSTRACT Cardiac pacemaking initiated by the sinus node is attributable to the interplay of several membrane currents. These include the depolarizing 'funny current' (If ) and the sodium-calcium exchanger current (INCX ). The latter is activated by ryanodine receptor (RyR)-mediated calcium (Ca(2+) ) release from the sarcoplasmic reticulum (SR). Another SR Ca(2+) release channel, the inositol-1,4,5-triphosphate receptor (IP3 R), has been implicated in the generation of spontaneous Ca(2+) release in atrial and ventricular cardiomyocytes. Whether IP3 R-mediated Ca(2+) release also influences SAN automaticity is controversial, in part due to the confounding influence of periodic Ca(2+) flux through the sarcolemma accompanying each beat. We took advantage of atrial-specific sodium-calcium exchanger (NCX) knockout (KO) SAN cells to study the influence of IP3 signalling on cardiac pacemaking in a system where periodic intracellular Ca(2+) cycling persists despite the absence of depolarization or Ca(2+) flux across the sarcolemma. We recorded confocal line scans of spontaneous Ca(2+) release in WT and NCX KO SAN cells in the presence or absence of an IP3 R blocker (2-aminoethoxydiphenyl borate, 2-APB), or during block of IP3 production by the phospholipase C inhibitor U73122. 2-APB and U73122 decreased the frequency of spontaneous Ca(2+) transients and waves in WT and NCX KO cells, respectively. Alternatively, increased IP3 production induced by phenylephrine increased Ca(2+) transient and wave frequency. We conclude that IP3 R-mediated SR Ca(2+) flux is crucial for initiating and modulating the RyR-mediated Ca(2+) cycling that regulates SAN pacemaking. Our results in NCX KO SAN cells also demonstrate that RyRs, but not NCX, are required for IP3 to modulate Ca(2+) clock frequency.
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Affiliation(s)
- Nidhi Kapoor
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Andrew Tran
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Jeanney Kang
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Rui Zhang
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Kenneth D Philipson
- Department of Physiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - Joshua I Goldhaber
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
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15
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Haworth TE, Haverinen J, Shiels HA, Vornanen M. Electrical excitability of the heart in a Chondrostei fish, the Siberian sturgeon (Acipenser baerii). Am J Physiol Regul Integr Comp Physiol 2014; 307:R1157-66. [PMID: 25163915 DOI: 10.1152/ajpregu.00253.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sturgeon (family Acipenseridae) are regarded as living fossils due to their ancient origin and exceptionally slow evolution. To extend our knowledge of fish cardiac excitability to a Chondrostei fish, we examined electrophysiological phenotype of the Siberian sturgeon ( Acipenser baerii) heart with recordings of epicardial ECG, intracellular action potentials (APs), and sarcolemmal ion currents. Epicardial ECG of A. baerii had the typical waveform of the vertebrate ECG with Q-T interval (average duration of ventricular AP) of 650 ± 30 ms and an intrinsic heart rate of 45.5 ± 5 beats min−1 at 20°C. Similar to other fish species, atrial AP was shorter in duration (402 ± 33 ms) than ventricular AP (585 ± 40) ( P < 0.05) at 20°C. Densities of atrial and ventricular Na+ currents were similar (−47.6 ± 4.5 and −53.2 ± 5.1 pA/pF, respectively) and close to the typical values of teleost hearts. Two major K+ currents, the inward rectifier K+ current ( IK1), and the delayed rectifier K+ current ( IKr) were found under basal conditions in sturgeon cardiomyocytes. The atrial IKr (3.3 ± 0.2 pA/pF) was about twice as large as the ventricular IKr (1.3 ± 0.4 pA/pF) ( P < 0.05) conforming to the typical pattern of teleost cardiac IKr. Divergent from other fishes, the ventricular IK1 was remarkably small (−2.5 ± 0.07 pA/pF) and not different from that of the atrial myocytes (−1.9 ± 0.06 pA/pF) ( P > 0.05). Two ligand-gated K+ currents were also found: ACh-activated inward rectifier ( IKACh) was present only in atrial cells, while ATP-sensitive K+ current ( IKATP) was activated by a mitochondrial blocker, CCCP, in both atrial and ventricular cells. The most striking difference to other fishes appeared in Ca2+ currents ( ICa). In atrial myocytes, ICa was predominated by nickel-sensitive and nifedipine-resistant T-type ICa, while ventricular myocytes had mainly nifedipine-sensitive and nickel-resistant L-type ICa. ICaT/ ICaL ratio of the sturgeon atrial myocytes (2.42) is the highest value ever measured for a vertebrate species. In ventricular myocytes, ICaT/ ICaL ratio was 0.09. With the exception of the large atrial ICaT and small ventricular IK1, electrical excitability of A. baerii heart is similar to that of teleost hearts.
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Affiliation(s)
- Thomas Eliot Haworth
- University of Manchester, Faculty of Life Sciences, Manchester, United Kingdom; and
| | - Jaakko Haverinen
- University of Eastern Finland, Department of Biology, Joensuu, Finland
| | - Holly A. Shiels
- University of Manchester, Faculty of Life Sciences, Manchester, United Kingdom; and
| | - Matti Vornanen
- University of Eastern Finland, Department of Biology, Joensuu, Finland
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Haverinen J, Egginton S, Vornanen M. Electrical Excitation of the Heart in a Basal Vertebrate, the European River Lamprey (Lampetra fluviatilis). Physiol Biochem Zool 2014; 87:817-28. [DOI: 10.1086/678954] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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