1
|
Li E, van der Heyden MAG. The network of cardiac K IR2.1: its function, cellular regulation, electrical signaling, diseases and new drug avenues. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03116-5. [PMID: 38683369 DOI: 10.1007/s00210-024-03116-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
The functioning of the human heart relies on complex electrical and communication systems that coordinate cardiac contractions and sustain rhythmicity. One of the key players contributing to this intricate system is the KIR2.1 potassium ion channel, which is encoded by the KCNJ2 gene. KIR2.1 channels exhibit abundant expression in both ventricular myocytes and Purkinje fibers, exerting an important role in maintaining the balance of intracellular potassium ion levels within the heart. And by stabilizing the resting membrane potential and contributing to action potential repolarization, these channels have an important role in cardiac excitability also. Either gain- or loss-of-function mutations, but also acquired impairments of their function, are implicated in the pathogenesis of diverse types of cardiac arrhythmias. In this review, we aim to elucidate the system functions of KIR2.1 channels related to cellular electrical signaling, communication, and their contributions to cardiovascular disease. Based on this knowledge, we will discuss existing and new pharmacological avenues to modulate their function.
Collapse
Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands.
| |
Collapse
|
2
|
Li C, Yang Y. Advancements in the study of inward rectifying potassium channels on vascular cells. Channels (Austin) 2023; 17:2237303. [PMID: 37463317 PMCID: PMC10355679 DOI: 10.1080/19336950.2023.2237303] [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: 05/16/2023] [Revised: 06/20/2023] [Accepted: 07/04/2023] [Indexed: 07/20/2023] Open
Abstract
Inward rectifier potassium channels (Kir channels) exist in a variety of cells and are involved in maintaining resting membrane potential and signal transduction in most cells, as well as connecting metabolism and membrane excitability of body cells. It is closely related to normal physiological functions of body and the occurrence and development of some diseases. Although the functional expression of Kir channels and their role in disease have been studied, they have not been fully elucidated. In this paper, the functional expression of Kir channels in vascular endothelial cells and smooth muscle cells and their changes in disease states were reviewed, especially the recent research progress of Kir channels in stem cells was introduced, in order to have a deeper understanding of Kir channels in vascular tissues and provide new ideas and directions for the treatment of related ion channel diseases.
Collapse
Affiliation(s)
- Chunshu Li
- Key Lab of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Lab of Sichuan Province, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yan Yang
- Key Lab of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Lab of Sichuan Province, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| |
Collapse
|
3
|
Chidipi B, Chang M, Cui M, Abou-Assali O, Reiser M, Pshenychnyi S, Logothetis DE, Teng MN, Noujaim SF. Bioengineered peptibodies as blockers of ion channels. Proc Natl Acad Sci U S A 2022; 119:e2212564119. [PMID: 36475947 PMCID: PMC9897444 DOI: 10.1073/pnas.2212564119] [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: 07/21/2022] [Accepted: 10/25/2022] [Indexed: 12/12/2022] Open
Abstract
We engineered and produced an ion channel blocking peptibody, that targets the acetylcholine-activated inwardly rectifying potassium current (IKACh). Peptibodies are chimeric proteins generated by fusing a biologically active peptide with the fragment crystallizable (Fc) region of the human immunoglobulin G (IgG). The IKACh blocking peptibody was engineered as a fusion between the human IgG1 Fc fragment and the IKACh inhibitor tertiapinQ (TP), a 21-amino acid synthetic peptidotoxin, originally isolated from the European honey bee venom. The peptibody was purified from the culture supernatant of human embryonic kidney (HEK) cells transfected with the peptibody construct. We tested the hypothesis that the bioengineered peptibody is bioactive and a potent blocker of IKACh. In HEK cells transfected with Kir3.1 and Kir3.4, the molecular correlates of IKACh, patch clamp showed that the peptibody was ~300-fold more potent than TP. Molecular dynamics simulations suggested that the increased potency could be due to an increased stabilization of the complex formed by peptibody-Kir3.1/3.4 channels compared to tertiapin-Kir3.1/3.4 channels. In isolated mouse myocytes, the peptibody blocked carbachol (Cch)-activated IKACh in atrial cells but did not affect the potassium inwardly rectifying background current in ventricular myocytes. In anesthetized mice, the peptibody abrogated the bradycardic effects of intraperitoneal Cch injection. Moreover, in aged mice, the peptibody reduced the inducibility of atrial fibrillation, likely via blocking constitutively active IKACh. Bioengineered anti-ion channel peptibodies can be powerful and highly potent ion channel blockers, with the potential to guide the development of modulators of ion channels or antiarrhythmic modalities.
Collapse
Affiliation(s)
- Bojjibabu Chidipi
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| | - Mengmeng Chang
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| | - Meng Cui
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Center for Drug Discovery, Northeastern University, Boston, MA02115
| | - Obada Abou-Assali
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| | - Michelle Reiser
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| | - Sergii Pshenychnyi
- Chemistry for Life Processes Institute, Northwestern University, Evanston, IL60208
| | - Diomedes E. Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Center for Drug Discovery, Northeastern University, Boston, MA02115
| | - Michael N. Teng
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| | - Sami F. Noujaim
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL33612
| |
Collapse
|
4
|
Saadeh K, Nantha Kumar N, Fazmin IT, Edling CE, Jeevaratnam K. Anti-malarial drugs: Mechanisms underlying their proarrhythmic effects. Br J Pharmacol 2022; 179:5237-5258. [PMID: 36165125 PMCID: PMC9828855 DOI: 10.1111/bph.15959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/06/2022] [Accepted: 04/28/2022] [Indexed: 01/12/2023] Open
Abstract
Malaria remains the leading cause of parasitic death in the world. Artemisinin resistance is an emerging threat indicating an imminent need for novel combination therapy. Given the key role of mass drug administration, it is pivotal that the safety of anti-malarial drugs is investigated thoroughly prior to widespread use. Cardiotoxicity, most prominently arrhythmic risk, has been a concern for anti-malarial drugs. We clarify the likely underlying mechanisms by which anti-malarial drugs predispose to arrhythmias. These relate to disruption of (1) action potential upstroke due to effects on the sodium currents, (2) action potential repolarisation due to effects on the potassium currents, (3) cellular calcium homeostasis, (4) mitochondrial function and reactive oxygen species production and (5) cardiac fibrosis. Together, these alterations promote arrhythmic triggers and substrates. Understanding these mechanisms is essential to assess the safety of these drugs, stratify patients based on arrhythmic risk and guide future anti-malarial drug development.
Collapse
Affiliation(s)
- Khalil Saadeh
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordUK,School of Clinical Medicine, Addenbrooke's HospitalUniversity of CambridgeCambridgeUK
| | | | - Ibrahim Talal Fazmin
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordUK,School of Clinical Medicine, Addenbrooke's HospitalUniversity of CambridgeCambridgeUK
| | | | | |
Collapse
|
5
|
Navarrete E, Díaz G, Salazar AM, Montúfar-Chaveznava R, Caldelas I. Long-term changes in the diurnal temporal regulation and set points of metabolic parameters associated with chronic maternal overnutrition in rabbits. Am J Physiol Endocrinol Metab 2022; 323:E503-E516. [PMID: 36288336 DOI: 10.1152/ajpendo.00144.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Metabolic syndrome (MS) and obesity have become a worldwide epidemic with an alarming prevalence in women of reproductive age. Maternal metabolic condition is considered a risk factor for adverse birth outcomes and long-term MS. In this study, we developed a rabbit model of maternal overnutrition via the chronic intake of a high-fat and carbohydrate diet (HFCD), and we determined the effects of this diet on maternal metabolism and offspring metabolic set points and temporal metabolic regulation in adult life. Before and during pregnancy, the female rabbits that consumed the HFCD exhibited significant changes in body weight, serum levels of analytes associated with carbohydrate and lipid metabolism, levels of liver and kidney damage markers, and liver histology. Our data suggest that rabbits are a valuable model for studying the development of MS associated with the chronic intake of unbalanced diets and fetal metabolic programming. Furthermore, the offspring of overnourished dams exhibited considerable changes in 24-h serum metabolite profiles in adulthood, with notable sexual dimorphism. These data suggest that maternal nutritional conditions due to the chronic intake of an HFCD adversely impact key elements related to the development of circadian rhythmicity in offspring.NEW & NOTEWORTHY Maternal overnutrition previous and during pregnancy leads to long-term changes in the 24-h regulation and setpoint of metabolic profiles of the offspring.
Collapse
Affiliation(s)
- Erika Navarrete
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Georgina Díaz
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Ana María Salazar
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | | | - Ivette Caldelas
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| |
Collapse
|
6
|
Xynogalos P, Rahm AK, Fried S, Chasan S, Scherer D, Seyler C, Katus HA, Frey N, Zitron E. Verapamil inhibits Kir2.3 channels by binding to the pore and interfering with PIP2 binding. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2022; 396:659-667. [PMID: 36445385 PMCID: PMC10042922 DOI: 10.1007/s00210-022-02342-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/15/2022] [Indexed: 11/30/2022]
Abstract
Abstract
The inwardly rectifying potassium current of the cardiomyocyte (IK1) is the main determinant of the resting potential. Ion channels Kir2.1, Kir2.2, and Kir2.3 form tetramers and are the molecular correlate of macroscopic IK1 current. Verapamil is an antiarrhythmic drug used to suppress atrial and ventricular arrhythmias. Its primary mechanism of action is via blocking calcium channels. In addition, it has been demonstrated to block IK1 current and the Kir2.1 subunit. Its effect on other subunits that contribute to IK1 current has not been studied to date. We therefore analyzed the effect of verapamil on the Kir channels 2.1, 2.2, and 2.3 in the Xenopus oocyte expression system. Kir2.1, Kir2.2, and Kir2.3 channels were heterologously expressed in Xenopus oocytes. Respective currents were measured with the voltage clamp technique and the effect of verapamil on the current was measured. At a concentration of 300 µM, verapamil inhibited Kir2.1 channels by 41.36% ± 2.7 of the initial current, Kir2.2 channels by 16.51 ± 3.6%, and Kir2.3 by 69.98 ± 4.2%. As a verapamil effect on kir2.3 was a previously unknown finding, we analyzed this effect further. At wash in with 300 µM verapamil, the maximal effect was seen within 20 min of the infusion. After washing out with control solution, there was only a partial current recovery. The current reduction from verapamil was the same at − 120 mV (73.2 ± 3.7%), − 40 mV (85.5 ± 6.5%), and 0 mV (61.5 ± 10.6%) implying no voltage dependency of the block. Using site directed mutations in putative binding sites, we demonstrated a decrease of effect with pore mutant E291A and absence of verapamil effect for D251A. With mutant I214L, which shows a stronger affinity for PIP2 binding, we observed a normalized current reduction to 61.9 ± 0.06% of the control current, which was significantly less pronounced compared to wild type channels. Verapamil blocks Kir2.1, Kir2.2, and Kir2.3 subunits. In Kir2.3, blockade is dependent on sites E291 and D251 and interferes with activation of the channel via PIP2. Interference with these sites and with PIP2 binding has also been described for other Kir channels blocking drugs. As Kir2.3 is preferentially expressed in atrium, a selective Kir2.3 blocking agent would constitute an interesting antiarrhythmic concept.
Collapse
|
7
|
Pharmacological and cardiovascular perspectives on the treatment of COVID-19 with chloroquine derivatives. Acta Pharmacol Sin 2020; 41:1377-1386. [PMID: 32968208 PMCID: PMC7509225 DOI: 10.1038/s41401-020-00519-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/20/2020] [Indexed: 01/08/2023] Open
Abstract
The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and an ongoing severe pandemic. Curative drugs specific for COVID-19 are currently lacking. Chloroquine phosphate and its derivative hydroxychloroquine, which have been used in the treatment and prevention of malaria and autoimmune diseases for decades, were found to inhibit SARS-CoV-2 infection with high potency in vitro and have shown clinical and virologic benefits in COVID-19 patients. Therefore, chloroquine phosphate was first used in the treatment of COVID-19 in China. Later, under a limited emergency-use authorization from the FDA, hydroxychloroquine in combination with azithromycin was used to treat COVID-19 patients in the USA, although the mechanisms of the anti-COVID-19 effects remain unclear. Preliminary outcomes from clinical trials in several countries have generated controversial results. The desperation to control the pandemic overrode the concerns regarding the serious adverse effects of chloroquine derivatives and combination drugs, including lethal arrhythmias and cardiomyopathy. The risks of these treatments have become more complex as a result of findings that COVID-19 is actually a multisystem disease. While respiratory symptoms are the major clinical manifestations, cardiovascular abnormalities, including arrhythmias, myocarditis, heart failure, and ischemic stroke, have been reported in a significant number of COVID-19 patients. Patients with preexisting cardiovascular conditions (hypertension, arrhythmias, etc.) are at increased risk of severe COVID-19 and death. From pharmacological and cardiovascular perspectives, therefore, the treatment of COVID-19 with chloroquine and its derivatives should be systematically evaluated, and patients should be routinely monitored for cardiovascular conditions to prevent lethal adverse events.
Collapse
|
8
|
Lozano WM, Parra G, Arias-Mutis OJ, Zarzoso M. Exercise Training Protocols in Rabbits Applied in Cardiovascular Research. Animals (Basel) 2020; 10:ani10081263. [PMID: 32722314 PMCID: PMC7459864 DOI: 10.3390/ani10081263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 11/20/2022] Open
Abstract
Simple Summary Several animal models have been used to understand the physiological adaptations produced by exercise training in the healthy and diseased cardiovascular system. Among those, the protocols for acute and chronic exercise in rabbits present several advantages compared to other large animal models. In addition, the rabbit model has important physiological similarities with humans. On the other hand, the design of the training protocol is a key factor to induce the physiological adaptations. Here, we review the different training protocols used in rabbits and the different physiological adaptations produced in the cardiovascular system, in normal and pathological conditions. Abstract Rabbit exercise protocols allow for the evaluation of physiological and biomechanical changes and responses to episodes of acute or chronic exercise. The observed physiological changes are normal responses to stress, that is, adaptive responses to maintain or restore homeostasis after acute exercise. Indeed, the rabbit model is advantageous since (a) it has important physiological similarities in terms of the functioning of multiple organ systems, and can quickly induce alterations in pathophysiological conditions that resemble those of humans, and (b) it allows the implementation of a low-cost model in comparison with other large animals. When designing an exercise training protocol for rabbits, it is important to consider variables such as race, gender, age and, especially, training parameters such as volume, intensity, or rest, among others, to determine the outcome of the research. Therefore, the objective of this review is to identify and analyze exercise training protocols in rabbits in different experimental applications and the various physiological adaptations that are presented, with special focus in cardiovascular adaptations.
Collapse
Affiliation(s)
- Wilson M. Lozano
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
| | - Germán Parra
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
- INCLIVA, Instituto de Investigación Sanitaria, 46010 Valencia, Spain
| | - Oscar J. Arias-Mutis
- Department of Physiology, Universitat de València, 46010 Valencia, Spain; (W.M.L.); (G.P.); (O.J.A.-M.)
- INCLIVA, Instituto de Investigación Sanitaria, 46010 Valencia, Spain
- CIBERCV, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Manuel Zarzoso
- Department of Physiotherapy, Universitat de València, 46010 Valencia, Spain
- Correspondence: ; Tel.: +34-963-983-853
| |
Collapse
|
9
|
Mubagwa K. Cardiac effects and toxicity of chloroquine: a short update. Int J Antimicrob Agents 2020; 56:106057. [PMID: 32565195 PMCID: PMC7303034 DOI: 10.1016/j.ijantimicag.2020.106057] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/07/2020] [Accepted: 06/14/2020] [Indexed: 02/07/2023]
Abstract
There is currently increased interest in the use of the antimalarial drugs chloroquine and hydroxychloroquine for the treatment of other diseases, including cancer and viral infections such as coronavirus disease 2019 (COVID-19). However, the risk of cardiotoxic effects tends to limit their use. In this review, the effects of these drugs on the electrical and mechanical activities of the heart as well as on remodelling of cardiac tissue are presented and the underlying molecular and cellular mechanisms are discussed. The drugs can have proarrhythmic as well as antiarrhythmic actions resulting from their inhibition of ion channels, including voltage-dependent Na+ and Ca2+ channels, background and voltage-dependent K+ channels, and pacemaker channels. The drugs also exert a vagolytic effect due at least in part to a muscarinic receptor antagonist action. They also interfere with normal autophagy flux, an effect that could aggravate ischaemia/reperfusion injury or post-infarct remodelling. Most of the toxic effects occur at high concentrations, following prolonged drug administration or in the context of drug associations.
Collapse
Affiliation(s)
- Kanigula Mubagwa
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Department of Basic Sciences, Faculty of Medicine, Université Catholique de Bukavu, Bukavu, DR Congo.
| |
Collapse
|
10
|
Shuai W, Kong B, Fu H, Jiang X, Huang H. The effect of MD1 on potassium and L-type calcium current of cardiomyocytes from high-fat diet mice. Channels (Austin) 2020; 14:181-189. [PMID: 32491968 PMCID: PMC7515570 DOI: 10.1080/19336950.2020.1772628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Myeloid differentiation protein 1 (MD1) is exerted an anti-arrhythmic effect in obese mice. Therefore, we sought to clarify whether MD1 can alter the electrophysiological remodeling of cardiac myocytes from obese mice by regulating voltage-gated potassium current and calcium current. MD1 knock-out (KO) and wild type (WT) mice were given a high-fat diet (HFD) for 20 weeks, starting at the age of 6 weeks. The potential electrophysiological mechanisms were estimated by whole-cell patch-clamp and molecular analysis. After 20-week HFD feeding, action potential duration (APD) from left ventricular myocytes of MD1-KO mice revealed APD20, APD50, and APD90 were profoundly enlarged. Furthermore, HFD mice showed a decrease in the fast transient outward potassium currents (Ito,f), slowly inactivating potassium current (IK, slow), and inward rectifier potassium current (IK1). Besides, HFD-fed mice showed that the current density of ICaL was significantly lower, and the haft inactivation voltage was markedly shifted right. These HFD induced above adverse effects were further exacerbated in KO mice. The mRNA expression of potassium ion channels (Kv4.2, Kv4.3, Kv2.1, Kv1.5, and Kir2.1) and calcium ion channel (Cav1.2) was markedly decreased in MD1-KO HFD-fed mice. MD1 deletion led to down-regulated potassium currents and slowed inactivation of L-type calcium channel in an obese mice model.
Collapse
Affiliation(s)
- Wei Shuai
- Department of Cardiology, Renmin Hospital of Wuhan University , Wuhan, Hubei, China.,Cardiovascular Research Institute of Wuhan University , Wuhan, Hubei, China.,Hubei Key Laboratory of Cardiology , Wuhan, Hubei, China
| | - Bin Kong
- Department of Cardiology, Renmin Hospital of Wuhan University , Wuhan, Hubei, China.,Cardiovascular Research Institute of Wuhan University , Wuhan, Hubei, China.,Hubei Key Laboratory of Cardiology , Wuhan, Hubei, China
| | - Hui Fu
- Department of Cardiology, Renmin Hospital of Wuhan University , Wuhan, Hubei, China.,Cardiovascular Research Institute of Wuhan University , Wuhan, Hubei, China.,Hubei Key Laboratory of Cardiology , Wuhan, Hubei, China
| | - Xiaobo Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University , Wuhan, Hubei, China.,Cardiovascular Research Institute of Wuhan University , Wuhan, Hubei, China.,Hubei Key Laboratory of Cardiology , Wuhan, Hubei, China
| | - He Huang
- Department of Cardiology, Renmin Hospital of Wuhan University , Wuhan, Hubei, China.,Cardiovascular Research Institute of Wuhan University , Wuhan, Hubei, China.,Hubei Key Laboratory of Cardiology , Wuhan, Hubei, China
| |
Collapse
|
11
|
Tobón C, Palacio LC, Chidipi B, Slough DP, Tran T, Tran N, Reiser M, Lin YS, Herweg B, Sayad D, Saiz J, Noujaim S. The Antimalarial Chloroquine Reduces the Burden of Persistent Atrial Fibrillation. Front Pharmacol 2019; 10:1392. [PMID: 31827438 PMCID: PMC6890839 DOI: 10.3389/fphar.2019.01392] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/31/2019] [Indexed: 12/31/2022] Open
Abstract
In clinical practice, reducing the burden of persistent atrial fibrillation by pharmacological means is challenging. We explored if blocking the background and the acetylcholine-activated inward rectifier potassium currents (IK1 and IKACh) could be antiarrhythmic in persistent atrial fibrillation. We thus tested the hypothesis that blocking IK1 and IKACh with chloroquine decreases the burden of persistent atrial fibrillation. We used patch clamp to determine the IC50 of IK1 and IKACh block by chloroquine and molecular modeling to simulate the interaction between chloroquine and Kir2.1 and Kir3.1, the molecular correlates of IK1 and IKACh. We then tested, as a proof of concept, if oral chloroquine administration to a patient with persistent atrial fibrillation can decrease the arrhythmia burden. We also simulated the effects of chloroquine in a 3D model of human atria with persistent atrial fibrillation. In patch clamp the IC50 of IK1 block by chloroquine was similar to that of IKACh. A 14-day regimen of oral chloroquine significantly decreased the burden of persistent atrial fibrillation in a patient. Mathematical simulations of persistent atrial fibrillation in a 3D model of human atria suggested that chloroquine prolonged the action potential duration, leading to failure of reentrant excitation, and the subsequent termination of the arrhythmia. The combined block of IK1 and IKACh can be a targeted therapeutic strategy for persistent atrial fibrillation.
Collapse
Affiliation(s)
| | | | - Bojjibabu Chidipi
- Molecular Pharmacology and Physiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Diana P Slough
- Department of Chemistry, Tufts University, Medford, MA, United States
| | - Thanh Tran
- Cardiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Nhi Tran
- Cardiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Michelle Reiser
- Molecular Pharmacology and Physiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, MA, United States
| | - Bengt Herweg
- Cardiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Dany Sayad
- Cardiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Javier Saiz
- Ci2 B, Universitat Politècnica de València, Valencia, Spain
| | - Sami Noujaim
- Molecular Pharmacology and Physiology Department, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| |
Collapse
|
12
|
Calvo D, Filgueiras-Rama D, Jalife J. Mechanisms and Drug Development in Atrial Fibrillation. Pharmacol Rev 2018; 70:505-525. [PMID: 29921647 PMCID: PMC6010660 DOI: 10.1124/pr.117.014183] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation is a highly prevalent cardiac arrhythmia and the most important cause of embolic stroke. Although genetic studies have identified an increasing assembly of AF-related genes, the impact of these genetic discoveries is yet to be realized. In addition, despite more than a century of research and speculation, the molecular and cellular mechanisms underlying AF have not been established, and therapy for AF, particularly persistent AF, remains suboptimal. Current antiarrhythmic drugs are associated with a significant rate of adverse events, particularly proarrhythmia, which may explain why many highly symptomatic AF patients are not receiving any rhythm control therapy. This review focuses on recent advances in AF research, including its epidemiology, genetics, and pathophysiological mechanisms. We then discuss the status of antiarrhythmic drug therapy for AF today, reviewing molecular mechanisms, and the possible clinical use of some of the new atrial-selective antifibrillatory agents, as well as drugs that target atrial remodeling, inflammation and fibrosis, which are being tested as upstream therapies to prevent AF perpetuation. Altogether, the objective is to highlight the magnitude and endemic dimension of AF, which requires a significant effort to develop new and effective antiarrhythmic drugs, but also improve AF prevention and treatment of risk factors that are associated with AF complications.
Collapse
Affiliation(s)
- David Calvo
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - David Filgueiras-Rama
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - José Jalife
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| |
Collapse
|
13
|
Takemoto Y, Slough DP, Meinke G, Katnik C, Graziano ZA, Chidipi B, Reiser M, Alhadidy MM, Ramirez R, Salvador-Montañés O, Ennis S, Guerrero-Serna G, Haburcak M, Diehl C, Cuevas J, Jalife J, Bohm A, Lin YS, Noujaim SF. Structural basis for the antiarrhythmic blockade of a potassium channel with a small molecule. FASEB J 2018; 32:1778-1793. [PMID: 29162702 DOI: 10.1096/fj.201700349r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The acetylcholine-activated inward rectifier potassium current ( IKACh) is constitutively active in persistent atrial fibrillation (AF). We tested the hypothesis that the blocking of IKACh with the small molecule chloroquine terminates persistent AF. We used a sheep model of tachypacing-induced, persistent AF, molecular modeling, electrophysiology, and structural biology approaches. The 50% inhibition/inhibitory concentration of IKACh block with chloroquine, measured by patch clamp, was 1 μM. In optical mapping of sheep hearts with persistent AF, 1 μM chloroquine restored sinus rhythm. Molecular modeling suggested that chloroquine blocked the passage of a hydrated potassium ion through the intracellular domain of Kir3.1 (a molecular correlate of IKACh) by interacting with residues D260 and F255, in proximity to I228, Q227, and L299. 1H 15N heteronuclear single-quantum correlation of purified Kir3.1 intracellular domain confirmed the modeling results. F255, I228, Q227, and L299 underwent significant chemical-shift perturbations upon drug binding. We then crystallized and solved a 2.5 Å X-ray structure of Kir3.1 with F255A mutation. Modeling of chloroquine binding to the mutant channel suggested that the drug's binding to the pore becomes off centered, reducing its ability to block a hydrated potassium ion. Patch clamp validated the structural and modeling data, where the F255A and D260A mutations significantly reduced IKACh block by chloroquine. With the use of numerical and structural biology approaches, we elucidated the details of how a small molecule could block an ion channel and exert antiarrhythmic effects. Chloroquine binds the IKACh channel at a site formed by specific amino acids in the ion-permeation pathway, leading to decreased IKACh and the subsequent termination of AF.-Takemoto, Y., Slough, D. P., Meinke, G., Katnik, C., Graziano, Z. A., Chidipi, B., Reiser, M., Alhadidy, M. M., Ramirez, R., Salvador-Montañés, O., Ennis, S., Guerrero-Serna, G., Haburcak, M., Diehl, C., Cuevas, J., Jalife, J., Bohm, A., Lin,Y.-S., Noujaim, S. F. Structural basis for the antiarrhythmic blockade of a potassium channel with a small molecule.
Collapse
Affiliation(s)
- Yoshio Takemoto
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.,Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Diana P Slough
- Department of Chemistry, Tufts University, Medford, Massachusetts, USA
| | - Gretchen Meinke
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Christopher Katnik
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| | | | - Bojjibabu Chidipi
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| | - Michelle Reiser
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| | - Mohammed M Alhadidy
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| | - Rafael Ramirez
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Steven Ennis
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Marian Haburcak
- Department of Biology, Brandeis University, Waltham, Massachusetts, USA
| | - Carl Diehl
- Saromics Biostructures, Copenhagen, Denmark; and
| | - Javier Cuevas
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| | - Jose Jalife
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA.,Centro de Nacional de Investigaciones Cardiovasculares Carlos III and Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares , Madrid, Spain
| | - Andrew Bohm
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, Massachusetts, USA
| | - Sami F Noujaim
- Molecular Pharmacology and Physiology Department, University of South Florida, Tampa, Florida, USA
| |
Collapse
|
14
|
Ji Y, Veldhuis MG, Zandvoort J, Romunde FL, Houtman MJC, Duran K, van Haaften G, Zangerl-Plessl EM, Takanari H, Stary-Weinzinger A, van der Heyden MAG. PA-6 inhibits inward rectifier currents carried by V93I and D172N gain-of-function K IR2.1 channels, but increases channel protein expression. J Biomed Sci 2017; 24:44. [PMID: 28711067 PMCID: PMC5513211 DOI: 10.1186/s12929-017-0352-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/11/2017] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND The inward rectifier potassium current IK1 contributes to a stable resting membrane potential and phase 3 repolarization of the cardiac action potential. KCNJ2 gain-of-function mutations V93I and D172N associate with increased IK1, short QT syndrome type 3 and congenital atrial fibrillation. Pentamidine-Analogue 6 (PA-6) is an efficient (IC50 = 14 nM with inside-out patch clamp methodology) and specific IK1 inhibitor that interacts with the cytoplasmic pore region of the KIR2.1 ion channel, encoded by KCNJ2. At 10 μM, PA-6 increases wild-type (WT) KIR2.1 expression in HEK293T cells upon chronic treatment. We hypothesized that PA-6 will interact with and inhibit V93I and D172N KIR2.1 channels, whereas impact on channel expression at the plasma membrane requires higher concentrations. METHODS Molecular modelling was performed with the human KIR2.1 closed state homology model using FlexX. WT and mutant KIR2.1 channels were expressed in HEK293 cells. Patch-clamp single cell electrophysiology measurements were performed in the whole cell and inside-out mode of the patch clamp method. KIR2.1 expression level and localization were determined by western blot analysis and immunofluorescence microscopy, respectively. RESULTS PA-6 docking in the V93I/D172N double mutant homology model of KIR2.1 demonstrated that mutations and drug-binding site are >30 Å apart. PA-6 inhibited WT and V93I outward currents with similar potency (IC50 = 35.5 and 43.6 nM at +50 mV for WT and V93I), whereas D172N currents were less sensitive (IC50 = 128.9 nM at +50 mV) using inside-out patch-clamp electrophysiology. In whole cell mode, 1 μM of PA-6 inhibited outward IK1 at -50 mV by 28 ± 36%, 18 ± 20% and 10 ± 6%, for WT, V93I and D172N channels respectively. Western blot analysis demonstrated that PA-6 (5 μM, 24 h) increased KIR2.1 expression levels of WT (6.3 ± 1.5 fold), and V93I (3.9 ± 0.9) and D172N (4.8 ± 2.0) mutants. Immunofluorescent microscopy demonstrated dose-dependent intracellular KIR2.1 accumulation following chronic PA-6 application (24 h, 1 and 5 μM). CONCLUSIONS 1) KCNJ2 gain-of-function mutations V93I and D172N in the KIR2.1 ion channel do not impair PA-6 mediated inhibition of IK1, 2) PA-6 elevates KIR2.1 protein expression and induces intracellular KIR2.1 accumulation, 3) PA-6 is a strong candidate for further preclinical evaluation in treatment of congenital SQT3 and AF.
Collapse
Affiliation(s)
- Yuan Ji
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Marlieke G. Veldhuis
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Jantien Zandvoort
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Fee L. Romunde
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Marien J. C. Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Karen Duran
- Center for Molecular Medicine, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gijs van Haaften
- Center for Molecular Medicine, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Hiroki Takanari
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | - Marcel A. G. van der Heyden
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| |
Collapse
|
15
|
Scherer D, Schworm B, Seyler C, Xynogalos P, Scholz EP, Thomas D, Katus HA, Zitron E. Inhibition of inwardly rectifying Kir2.x channels by the novel anti-cancer agent gambogic acid depends on both pore block and PIP 2 interference. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:701-710. [PMID: 28365825 DOI: 10.1007/s00210-017-1372-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/23/2017] [Indexed: 12/21/2022]
Abstract
The caged xanthone gambogic acid (GA) is a novel anti-cancer agent which exhibits anti-proliferative, anti-inflammatory and cytotoxic effects in many types of cancer tissues. In a recent phase IIa study, GA exhibits a favourable safety profile. However, limited data are available concerning its interaction with cardiac ion channels. Heteromeric assembly of Kir2.x channels underlies the cardiac inwardly rectifying IK1 current which is responsible for the stabilization of the diastolic resting membrane potential. Inhibition of the cardiac IK1 current may lead to ventricular arrhythmia due to delayed afterdepolarizations. Compared to Kv2.1, hERG and Kir1.1, a slow, delayed inhibition of Kir2.1 channels by GA in a mammalian cell line was reported before but no data exist in literature concerning action of GA on homomeric Kir2.2 and Kir2.3 and heteromeric Kir2.x channels. Therefore, the aim of this study was to provide comparative data on the effect of GA on homomeric and heteromeric Kir2.x channels. Homomeric and heteromeric Kir2.x channels were heterologously expressed in Xenopus oocytes, and the two-microelectrode voltage-clamp technique was used to record Kir2.x currents. To investigate the mechanism of the channel inhibition by GA, alanine-mutated Kir2.x channels with modifications in the channels pore region or at phosphatidylinositol 4,5-bisphosphate (PIP2)-binding sites were employed. GA caused a slow inhibition of homomeric and heteromeric Kir2.x channels at low micromolar concentrations (with IC50 Kir2.1/2.2 < Kir2.2 < Kir2.2/2.3 < Kir2.3 < Kir2.1 < Kir2.1/2.3). The effect did not reach saturation within 60 min and was not reversible upon washout for 30 min. The inhibition showed no strong voltage dependence. We provide evidence for a combination of direct channel pore blockade and a PIP2-dependent mechanism as a molecular basis for the observed effect. We conclude that Kir2.x channel inhibition by GA may be relevant in patients with pre-existing cardiac disorders such as chronic heart failure or certain rhythm disorders and recommend a close cardiac monitoring for those patients when treated with GA.
Collapse
Affiliation(s)
- Daniel Scherer
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
| | - Benedikt Schworm
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Panagiotis Xynogalos
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Eberhard P Scholz
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Edgar Zitron
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| |
Collapse
|
16
|
Chloroquine blocks the Kir4.1 channels by an open-pore blocking mechanism. Eur J Pharmacol 2017; 800:40-47. [PMID: 28216048 DOI: 10.1016/j.ejphar.2017.02.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 02/03/2017] [Accepted: 02/15/2017] [Indexed: 11/23/2022]
Abstract
Kir4.1 channels have been implicated in various physiological processes, mainly in the K+ homeostasis of the central nervous system and in the control of glial function and neuronal excitability. Even though, pharmacological research of these channels is very limited. Chloroquine (CQ) is an amino quinolone derivative known to inhibit Kir2.1 and Kir6.2 channels with different action mechanism and binding site. Here, we employed patch-clamp methods, mutagenesis analysis, and molecular modeling to characterize the molecular pharmacology of Kir4.1 inhibition by CQ. We found that this drug inhibits Kir4.1 channels heterologously expressed in HEK-293 cells. CQ produced a fast-onset voltage-dependent pore-blocking effect on these channels. In inside-out patches, CQ showed notable higher potency (IC50 ≈0.5μM at +50mV) and faster onset of block when compared to whole-cell configuration (IC50 ≈7μM at +60mV). Also, CQ showed a voltage-dependent unblock with repolarization. These results suggest that the drug directly blocks Kir4.1 channels by a pore-plugging mechanism. Moreover, we found that two residues (Thr128 and Glu158), facing the central cavity and located within the transmembrane pore, are particularly important structural determinants of CQ block. This evidence was similar to what was previously reported with Kir6.2, but distinct from the interaction site (cytoplasmic pore) CQ-Kir2.1. Thus, our findings highlight the diversity of interaction sites and mechanisms that underlie amino quinolone inhibition of Kir channels.
Collapse
|
17
|
Koepple C, Scherer D, Seyler C, Scholz E, Thomas D, Katus HA, Zitron E. Dual Mechanism for Inhibition of Inwardly Rectifying Kir2.x Channels by Quinidine Involving Direct Pore Block and PIP 2-interference. J Pharmacol Exp Ther 2017; 361:209-218. [PMID: 28188270 DOI: 10.1124/jpet.116.238287] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/08/2017] [Indexed: 11/22/2022] Open
Abstract
Class IA antiarrhythmic drug quinidine was one of the first clinically used compounds to terminate atrial fibrillation and acts as multichannel inhibitor with well-documented inhibitory effects on several cardiac potassium channels. In the mammalian heart, heteromeric assembly of Kir2.1-2.3 channels underlies IK1 current. Although a low-affinity block of quinidine on Kir2.1 has already been described, a comparative analysis of effects on other Kir2.x channels has not been performed to date. Therefore, we analyzed the effects of quinidine on wild-type and mutant Kir2.x channels in the Xenopus oocyte expression system. Quinidine exerted differential inhibitory effects on Kir2.x channels with the highest affinity toward Kir2.3 subunits. Onset of block was slow and solely reversible in Kir2.2 subunits. Quinidine inhibited Kir2.x currents in a voltage-independent manner. By means of comparative Ala-scanning mutagenesis, we further found that residues E224, F254, D259, and E299 are essential for quinidine block in Kir2.1 subunits. Analogously, quinidine mediated Kir2.3 inhibition by binding corresponding residues E216, D247, D251, and E291. In contrast, Kir2.2 current block merely involved corresponding residue D260. Using channel mutants with altered (phosphatidylinositol 4,5-bisphosphate PIP2) affinities, we were able to demonstrate that high PIP2 affinities (i.e., Kir2.3 I214L) correlate with low quinidine sensitivity. Inversely, mutant channels interacting only weakly with PIP2 (i.e., Kir2.1 K182Q, and L221I) are prone to a higher inhibitory effect. Thus, we conclude that inhibition of Kir2.x channels by quinidine is mediated by joint modes of action involving direct cytoplasmic pore block and an impaired channel stabilization via interference with PIP2.
Collapse
Affiliation(s)
- Christoph Koepple
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Daniel Scherer
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Eberhard Scholz
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| | - Edgar Zitron
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (C.K., D.S., C.S., E.S., D.T., H.A.K., E.Z.); DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany (C.S., E.S., D.T., H.A.K., E.Z.); and Department for Hand-, Plastic- and Reconstructive Surgery, BG Unfallklinik Ludwigshafen, University of Heidelberg, Heidelberg, Germany (C.K.)
| |
Collapse
|
18
|
Berenfeld O, Jalife J. Mechanisms of Atrial Fibrillation: Rotors, Ionic Determinants, and Excitation Frequency. Heart Fail Clin 2017; 12:167-78. [PMID: 26968663 DOI: 10.1016/j.hfc.2015.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia; however, therapy is suboptimal. We review recent data on dynamics of wave propagation during AF and its mechanistic link to the substrate. Data show that the dominant frequency (DF) increase during transition to persistent AF may be explained by rotor acceleration. We discuss how translation of experimentally derived understanding of the rotors may find its way into the clinic, focusing on studies analyzing spatial distribution of DF in the atria of patients with paroxysmal versus persistent AF, and how that knowledge might contribute to improve the outcome of AF ablation procedures.
Collapse
Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
| |
Collapse
|
19
|
Hoeker GS, Skarsfeldt MA, Jespersen T, Poelzing S. Electrophysiologic effects of the IK1 inhibitor PA-6 are modulated by extracellular potassium in isolated guinea pig hearts. Physiol Rep 2017; 5:e13120. [PMID: 28087819 PMCID: PMC5256165 DOI: 10.14814/phy2.13120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 12/14/2016] [Indexed: 12/02/2022] Open
Abstract
The pentamidine analog PA-6 was developed as a specific inward rectifier potassium current (IK1) antagonist, because established inhibitors either lack specificity or have side effects that prohibit their use in vivo. We previously demonstrated that BaCl2, an established IK1 inhibitor, could prolong action potential duration (APD) and increase cardiac conduction velocity (CV). However, few studies have addressed whether targeted IK1 inhibition similarly affects ventricular electrophysiology. The aim of this study was to determine the effects of PA-6 on cardiac repolarization and conduction in Langendorff-perfused guinea pig hearts. PA-6 (200 nm) or vehicle was perfused into ex-vivo guinea pig hearts for 60 min. Hearts were optically mapped with di-4-ANEPPS to quantify CV and APD at 90% repolarization (APD90). Ventricular APD90 was significantly prolonged in hearts treated with PA-6 (115 ± 2% of baseline; P < 0.05), but not vehicle (105 ± 2% of baseline). PA-6 slightly, but significantly, increased transverse CV by 7%. PA-6 significantly prolonged APD90 during hypokalemia (2 mmol/L [K+]o), although to a lesser degree than observed at 4.56 mmol/L [K+]o In contrast, the effect of PA-6 on CV was more pronounced during hypokalemia, where transverse CV with PA-6 (24 ± 2 cm/sec) was significantly faster than with vehicle (13 ± 3 cm/sec, P < 0.05). These results show that under normokalemic conditions, PA-6 significantly prolonged APD90, whereas its effect on CV was modest. During hypokalemia, PA-6 prolonged APD90 to a lesser degree, but profoundly increased CV Thus, in intact guinea pig hearts, the electrophysiologic effects of the IK1 inhibitor, PA-6, are [K+]o-dependent.
Collapse
Affiliation(s)
- Gregory S Hoeker
- Biomedical Engineering and Mechanics, Center for Heart and Regenerative Medicine, Virginia Tech Virginia Tech Carilion Research Institute, Roanoke, Virginia
| | - Mark A Skarsfeldt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Steven Poelzing
- Biomedical Engineering and Mechanics, Center for Heart and Regenerative Medicine, Virginia Tech Virginia Tech Carilion Research Institute, Roanoke, Virginia
| |
Collapse
|
20
|
Berenfeld O. The Major Role of IK1 in Mechanisms of Rotor Drift in the Atria: A Computational Study. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2016; 10:71-79. [PMID: 28096699 PMCID: PMC5175588 DOI: 10.4137/cmc.s39773] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 11/17/2016] [Accepted: 11/20/2016] [Indexed: 12/19/2022]
Abstract
Maintenance of paroxysmal atrial fibrillation (AF) by fast rotors in the left atrium (LA) or at the pulmonary veins (PVs) is not fully understood. This review describes the role of the heterogeneous distribution of transmembrane currents in the PVs and LA junction (PV-LAJ) in the localization of rotors in the PVs. Experimentally observed heterogeneities in IK1, IKs, IKr, Ito, and ICaL in the PV-LAJ were incorporated into models of human atrial kinetics to simulate various conditions and investigate rotor drifting mechanisms. Spatial gradients in the currents resulted in shorter action potential duration, less negative minimum diastolic potential, slower upstroke and conduction velocity for rotors in the PV region than in the LA. Rotors under such conditions drifted toward the PV and stabilized at the less excitable region. Our simulations suggest that IK1 heterogeneity is dominant in determining the drift direction through its impact on the excitability gradient. These results provide a novel framework for understanding the complex dynamics of rotors in AF.
Collapse
Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, Internal Medicine and Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
21
|
Kushiyama Y, Honjo H, Niwa R, Takanari H, Yamazaki M, Takemoto Y, Sakuma I, Kodama I, Kamiya K. Partial IK1 blockade destabilizes spiral wave rotation center without inducing wave breakup and facilitates termination of reentrant arrhythmias in ventricles. Am J Physiol Heart Circ Physiol 2016; 311:H750-8. [PMID: 27422985 DOI: 10.1152/ajpheart.00228.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/13/2016] [Indexed: 11/22/2022]
Abstract
It has been reported that blockade of the inward rectifier K(+) current (IK1) facilitates termination of ventricular fibrillation. We hypothesized that partial IK1 blockade destabilizes spiral wave (SW) re-entry, leading to its termination. Optical action potential (AP) signals were recorded from left ventricles of Langendorff-perfused rabbit hearts with endocardial cryoablation. The dynamics of SW re-entry were analyzed during ventricular tachycardia (VT), induced by cross-field stimulation. Intercellular electrical coupling in the myocardial tissue was evaluated by the space constant. In separate experiments, AP recordings were made using the microelectrode technique from right ventricular papillary muscles of rabbit hearts. Ba(2+) (10-50 μM) caused a dose-dependent prolongation of VT cycle length and facilitated termination of VT in perfused hearts. Baseline VT was maintained by a stable rotor, where an SW rotated around an I-shaped functional block line (FBL). Ba(2+) at 10 μM prolonged I-shaped FBL and phase-singularity trajectory, whereas Ba(2+) at 50 μM transformed the SW rotation dynamics from a stable linear pattern to unstable circular/cycloidal meandering. The SW destabilization was not accompanied by SW breakup. Under constant pacing, Ba(2+) caused a dose-dependent prolongation of APs, and Ba(2+) at 50 μM decreased conduction velocity. In papillary muscles, Ba(2+) at 50 μM depolarized the resting membrane potential. The space constant was increased by 50 μM Ba(2+) Partial IK1 blockade destabilizes SW rotation dynamics through a combination of prolongation of the wave length, reduction of excitability, and enhancement of electrotonic interactions, which facilitates termination of ventricular tachyarrhythmias.
Collapse
Affiliation(s)
- Yasunori Kushiyama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Haruo Honjo
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Ryoko Niwa
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Hiroki Takanari
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Yoshio Takemoto
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Ichiro Sakuma
- Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Itsuo Kodama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan; and
| |
Collapse
|
22
|
Afifi A. CTS trials network: Rate control vs rhythm control for atrial fibrillation after cardiac surgery - Do bitter pills have blessed effects? Glob Cardiol Sci Pract 2016; 2016:e201615. [PMID: 29043263 PMCID: PMC5642745 DOI: 10.21542/gcsp.2016.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
New onset AF is a very common sequel of cardiac surgery with an incidence reaching 50% in some studies. This post-operative complication leads to increased morbidity, hospital stay and, consequently, hospital costs1. Currently there is a great variability in the management of this condition. Despite efforts to produce best practice guidelines2, what best to do for a patient who develops AF post-operatively remains a question. In a systematic attempt to find an answer to this question, the Cardiothoracic Trials Network have recently published the results of their trial “Rate Control Versus Rhythm Control for Atrial Fibrillation After Cardiac Surgery”3 (clinicaltrials.gov number: NCT02132767).
Collapse
|
23
|
Mitragynine and its potential blocking effects on specific cardiac potassium channels. Toxicol Appl Pharmacol 2016; 305:22-39. [PMID: 27260674 DOI: 10.1016/j.taap.2016.05.022] [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] [Received: 04/18/2016] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 02/07/2023]
Abstract
Mitragyna speciosa Korth is known for its euphoric properties and is frequently used for recreational purposes. Several poisoning and fatal cases involving mitragynine have been reported but the underlying causes remain unclear. Human ether-a-go-go-related gene (hERG) encodes the cardiac IKr current which is a determinant of the duration of ventricular action potentials and QT interval. On the other hand, IK1, a Kir current mediated by Kir2.1 channel and IKACh, a receptor-activated Kir current mediated by GIRK channel are also known to be important in maintaining the cardiac function. This study investigated the effects of mitragynine on the current, mRNA and protein expression of hERG channel in hERG-transfected HEK293 cells and Xenopus oocytes. The effects on Kir2.1 and GIRK channels currents were also determined in the oocytes. The hERG tail currents following depolarization pulses were inhibited by mitragynine with an IC50 value of 1.62μM and 1.15μM in the transfected cell line and Xenopus oocytes, respectively. The S6 point mutations of Y652A and F656A attenuated the inhibitor effects of mitragynine, indicating that mitragynine interacts with these high affinity drug-binding sites in the hERG channel pore cavity which was consistent with the molecular docking simulation. Interestingly, mitragynine does not affect the hERG expression at the transcriptional level but inhibits the protein expression. Mitragynine is also found to inhibit IKACh current with an IC50 value of 3.32μM but has no significant effects on IK1. Blocking of both hERG and GIRK channels may cause additive cardiotoxicity risks.
Collapse
|
24
|
Li X, Hu H, Wang Y, Xue M, Li X, Cheng W, Xuan Y, Yin J, Yang N, Yan S. Valsartan Upregulates Kir2.1 in Rats Suffering from Myocardial Infarction via Casein Kinase 2. Cardiovasc Drugs Ther 2016; 29:209-18. [PMID: 26095682 PMCID: PMC4522035 DOI: 10.1007/s10557-015-6598-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Purpose Myocardial infarction (MI) results in an increased susceptibility to ventricular arrhythmias, due in part to decreased inward-rectifier K+ current (IK1), which is mediated primarily by the Kir2.1 protein. The use of renin-angiotensin-aldosterone system antagonists is associated with a reduced incidence of ventricular arrhythmias. Casein kinase 2 (CK2) binds and phosphorylates SP1, a transcription factor of KCNJ2 that encodes Kir2.1. Whether valsartan represses CK2 activation to ameliorate IK1 remodeling following MI remains unclear. Methods Wistar rats suffering from MI received either valsartan or saline for 7 days. The protein levels of CK2 and Kir2.1 were each detected via a Western blot analysis. The mRNA levels of CK2 and Kir2.1 were each examined via quantitative real-time PCR. Results CK2 expression was higher at the infarct border; and was accompanied by a depressed IK1/Kir2.1 protein level. Additionally, CK2 overexpression suppressed KCNJ2/Kir2.1 expression. By contrast, CK2 inhibition enhanced KCNJ2/Kir2.1 expression, establishing that CK2 regulates KCNJ2 expression. Among the rats suffering from MI, valsartan reduced CK2 expression and increased Kir2.1 expression compared with the rats that received saline treatment. In vitro, hypoxia increased CK2 expression and valsartan inhibited CK2 expression. The over-expression of CK2 in cells treated with valsartan abrogated its beneficial effect on KCNJ2/Kir2.1. Conclusions AT1 receptor antagonist valsartan reduces CK2 activation, increases Kir2.1 expression and thereby ameliorates IK1 remodeling after MI in the rat model.
Collapse
Affiliation(s)
- Xinran Li
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Valsartan Attenuates KIR2.1 by Downregulating the Th1 Immune Response in Rats Following Myocardial Infarction. J Cardiovasc Pharmacol 2016; 67:252-9. [DOI: 10.1097/fjc.0000000000000341] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
|
26
|
Filgueiras-Rama D, Jalife J. STRUCTURAL AND FUNCTIONAL BASES OF CARDIAC FIBRILLATION. DIFFERENCES AND SIMILARITIES BETWEEN ATRIA AND VENTRICLES. JACC Clin Electrophysiol 2016; 2:1-3. [PMID: 27042693 DOI: 10.1016/j.jacep.2015.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Evidence accumulated over the last 25 years suggests that, whether in the atria or ventricles, fibrillation may be explained by the self-organization of the cardiac electrical activity into rapidly spinning rotors giving way to spiral waves that break intermittently and result in fibrillatory conduction. The dynamics and frequency of such rotors depend on the ion channel composition, excitability and refractory properties of the tissues involved, as well as on the thickness and respective three-dimensional fiber structure of the atrial and ventricular chambers. Therefore, improving the understanding of fibrillation has required the use of multidisciplinary research approaches, including optical mapping, patch clamping and molecular biology, and the application of concepts derived from the theory of wave propagation in excitable media. Moreover, translation of such concepts to the clinic has recently opened new opportunities to apply novel mechanistic approaches to therapy, particularly during atrial fibrillation ablation. Here we review the current understanding of the manner in which the underlying myocardial structure and function influence rotor initiation and maintenance during cardiac fibrillation. We also examine relevant underlying differences and similarities between atrial fibrillation and ventricular fibrillation and evaluate the latest clinical mapping technologies used to identify rotors in either arrhythmia. Altogether, the data being discussed have significantly improved our understanding of the cellular and structural bases of cardiac fibrillation and pointed toward potentially exciting new avenues for more efficient and effective identification and therapy of the most complex cardiac arrhythmias.
Collapse
Affiliation(s)
- David Filgueiras-Rama
- Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC)., Myocardial Pathophysiology Area, Madrid, Spain; Hospital Clínico San Carlos, Cardiology department, Madrid, Spain
| | - José Jalife
- Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC)., Myocardial Pathophysiology Area, Madrid, Spain; Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, EEUU
| |
Collapse
|
27
|
van der Heyden MA, Jespersen T. Pharmacological exploration of the resting membrane potential reserve: Impact on atrial fibrillation. Eur J Pharmacol 2016; 771:56-64. [DOI: 10.1016/j.ejphar.2015.11.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/06/2015] [Accepted: 11/16/2015] [Indexed: 12/24/2022]
|
28
|
Li X, Hu H, Wang Y, Xue M, Li X, Cheng W, Xuan Y, Yin J, Yang N, Yan S. Valsartan ameliorates KIR2.1 in rats with myocardial infarction via the NF-κB-miR-16 pathway. Gene 2015; 590:201-9. [PMID: 26654716 DOI: 10.1016/j.gene.2015.11.047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/19/2015] [Accepted: 11/16/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND MicroRNAs have an important role in regulating arrhythmogenesis. MicroRNA-16 (miR-16) is predicted to target KCNJ2. The regulation of miR-16 is primarily due to NF-κB. Whether valsartan could downregulate miR-16 via the inhibition of NF-κB after MI and whether miR-16 targets KCNJ2 remain unclear. METHODS MI rats received valsartan or saline for 7days. The protein levels of NF-κB p65, inhibitor κBα (IκBα), and Kir2.1 were detected by Western blot analysis. The mRNA levels of Kir2.1 and miR-16 were examined by quantitative real-time PCR. Whole cell patch-clamp techniques were applied to record IK1. RESULTS MiR-16 expression was higher in the infarct border, and was accompanied by a depressed IK1/KIR2.1 level. Additionally, miR-16 overexpression suppressed KCNJ2/KIR2.1 expression. In contrast, miR-16 inhibition or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-16 target. In the MI rats, compared to saline treatment, valsartan reduced NF-κB p65 and miR-16 expression and increased IκBα and Kir2.1 expression. In vitro, angiotensin II increased miR-16 expression and valsartan inhibited it. Overexpressing miR-16 in cells treated with valsartan abrogated its beneficial effect on KCNJ2/Kir2.1. NF-κB activation directly upregulates miR-16 expression. CONCLUSIONS miR-16 controls KCNJ2 expression, and valsartan ameliorates Kir2.1 after MI partly depending on the NF-κB-miR-16 pathway.
Collapse
Affiliation(s)
- Xinran Li
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Hesheng Hu
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Ye Wang
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Mei Xue
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Xiaolu Li
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Wenjuan Cheng
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Yongli Xuan
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Jie Yin
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Na Yang
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Suhua Yan
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China.
| |
Collapse
|
29
|
Poudel P, Xu Y, Cui Z, Sharma D, Tian B, Paudel S. Atrial fibrillation: recent advances in understanding the role of microRNAs in atrial remodeling with an electrophysiological overview. Cardiology 2015; 131:58-67. [PMID: 25871909 DOI: 10.1159/000375403] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 01/17/2015] [Indexed: 01/08/2023]
Abstract
Atrial fibrillation (AF) is a highly prevalent condition associated with pronounced cardiovascular-related morbidity, mortality and socioeconomic burden. It accounts for more hospitalization days than does any other arrhythmia. This article reviews the basic electrophysiology of AF, electrical and structural remodeling in AF and recent advances in understanding the molecular mechanisms of AF in relation to specific microRNAs. This paper also reviews the potential role of microRNAs as novel therapeutic targets as well as biomarkers in the management of AF. AF shows characteristics typical of altered electrophysiology that promote ectopic activity and facilitate reentry, thereby contributing to the progression from short paroxysmal AF to a persistent, permanent form via atrial remodeling, even in the absence of progressive underlying heart disease. MicroRNAs have been suggested to influence the development of AF by regulating gene expression at the post-transcriptional level. Increasing evidence has identified various microRNA modifications and their impacts on AF initiation and maintenance through electrical and structural remodeling. The discovery of specific microRNAs as novel therapeutic targets and some experimental evidence implicating microRNAs as potential molecular diagnostic markers have had a significant impact on the diagnosis and management of AF and demand further research.
Collapse
Affiliation(s)
- Pradeep Poudel
- International College of Tianjin Medical University, Tianjin, PR China
| | | | | | | | | | | |
Collapse
|
30
|
Calvo CJ, Deo M, Zlochiver S, Millet J, Berenfeld O. Attraction of rotors to the pulmonary veins in paroxysmal atrial fibrillation: a modeling study. Biophys J 2014; 106:1811-21. [PMID: 24739180 DOI: 10.1016/j.bpj.2014.02.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 02/10/2014] [Accepted: 02/25/2014] [Indexed: 12/19/2022] Open
Abstract
Maintenance of paroxysmal atrial fibrillation (AF) by fast rotors in the left atrium (LA) or at the pulmonary veins (PVs) is not fully understood. To gain insight into this dynamic and complex process, we studied the role of the heterogeneous distribution of transmembrane currents in the PVs and LA junction (PV-LAJ) in the localization of rotors in the PVs. We also investigated whether simple pacing protocols could be used to predict rotor drift in the PV-LAJ. Experimentally observed heterogeneities in IK1, IKs, IKr, Ito, and ICaL in the PV-LAJ were incorporated into two- and pseudo three-dimensional models of Courtemanche-Ramirez-Nattel-Kneller human atrial kinetics to simulate various conditions and investigate rotor drifting mechanisms. Spatial gradients in the currents resulted in shorter action potential duration, minimum diastolic potential that was less negative, and slower upstroke and conduction velocity for rotors in the PV region than in the LA. Rotors under such conditions drifted toward the PV and stabilized at the shortest action potential duration and less-excitable region, consistent with drift direction under intercellular coupling heterogeneities and regardless of the geometrical constraint in the PVs. Simulations with various IK1 gradient conditions and current-voltage relationships substantiated its major role in the rotor drift. In our 1:1 pacing protocol, we found that among various action potential properties, only the minimum diastolic potential gradient was a rate-independent predictor of rotor drift direction. Consistent with experimental and clinical AF studies, simulations in an electrophysiologically heterogeneous model of the PV-LAJ showed rotor attraction toward the PV. Our simulations suggest that IK1 heterogeneity is dominant compared to other currents in determining the drift direction through its impact on the excitability gradient. These results provide a believed novel framework for understanding the complex dynamics of rotors in AF.
Collapse
Affiliation(s)
- Conrado J Calvo
- Center for Arrhythmia Research, Department of Internal Medicine, and Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; BioITACA Grupo de Bioingeniería, Instituto de Aplicaciones Avanzadas, Valencia, Spain; Departamento Ingeniería Electrónica, Universitat Politècnica de Valencia, Valencia, Spain
| | - Makarand Deo
- Center for Arrhythmia Research, Department of Internal Medicine, and Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Engineering, Norfolk State University, Norfolk, Virginia
| | - Sharon Zlochiver
- Center for Arrhythmia Research, Department of Internal Medicine, and Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, Tel Aviv University, Ramat Aviv, Israel
| | - José Millet
- BioITACA Grupo de Bioingeniería, Instituto de Aplicaciones Avanzadas, Valencia, Spain; Departamento Ingeniería Electrónica, Universitat Politècnica de Valencia, Valencia, Spain
| | - Omer Berenfeld
- Center for Arrhythmia Research, Department of Internal Medicine, and Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan.
| |
Collapse
|
31
|
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia; however, therapy is suboptimal. We review recent data on dynamics of wave propagation during AF and its mechanistic link to the substrate. Data show that the dominant frequency (DF) increase during transition to persistent AF may be explained by rotor acceleration. We discuss how translation of experimentally derived understanding of the rotors may find its way into the clinic, focusing on studies analyzing spatial distribution of DF in the atria of patients with paroxysmal versus persistent AF, and how that knowledge might contribute to improve the outcome of AF ablation procedures.
Collapse
Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
| |
Collapse
|
32
|
Activation of IK1 Channel by Zacopride Attenuates Left Ventricular Remodeling in Rats With Myocardial Infarction. J Cardiovasc Pharmacol 2014; 64:345-56. [DOI: 10.1097/fjc.0000000000000127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
33
|
Xynogalos P, Seyler C, Scherer D, Koepple C, Scholz EP, Thomas D, Katus HA, Zitron E. Class III antiarrhythmic drug dronedarone inhibits cardiac inwardly rectifying Kir2.1 channels through binding at residue E224. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:1153-61. [PMID: 25182566 DOI: 10.1007/s00210-014-1045-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 08/25/2014] [Indexed: 10/24/2022]
Abstract
Dronedarone is a novel class III antiarrhythmic drug that is widely used in atrial fibrillation. It has been shown in native cardiomyocytes that dronedarone inhibits cardiac inwardly rectifying current IK1 at high concentrations, which may contribute both its antifibrillatory efficacy and its potential proarrhythmic side effects. However, the underlying mechanism has not been studied in further detail to date. In the mammalian heart, heterotetrameric assembly of Kir2.x channels is the molecular basis of IK1 current. Therefore, we studied the effects of dronedarone on wild-type and mutant Kir2.x channels in the Xenopus oocyte expression system. Dronedarone inhibited Kir2.1 currents but had no effect on Kir2.2 or Kir2.3 currents. Onset of block was slow but completely reversible upon washout. Blockade of Kir2.1 channels did not exhibit strong voltage dependence or frequency dependence. In a screening with different Kir2.1 mutants lacking specific binding sites within the cytoplasmic pore region, we found that residue E224 is essential for binding of dronedarone to Kir2.1 channels. In conclusion, direct block of Kir2.1 channel subunits by dronedarone through binding at E224 may underlie its inhibitory effects on cardiac IK1 current.
Collapse
Affiliation(s)
- Panagiotis Xynogalos
- Department of Cardiology, University Hospital Heidelberg, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany,
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Baronas VA, Kurata HT. Inward rectifiers and their regulation by endogenous polyamines. Front Physiol 2014; 5:325. [PMID: 25221519 PMCID: PMC4145359 DOI: 10.3389/fphys.2014.00325] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 08/06/2014] [Indexed: 12/02/2022] Open
Abstract
Inwardly-rectifying potassium (Kir) channels contribute to maintenance of the resting membrane potential and regulation of electrical excitation in many cell types. Strongly rectifying Kir channels exhibit a very steep voltage dependence resulting in silencing of their activity at depolarized membrane voltages. The mechanism underlying this steep voltage dependence is blockade by endogenous polyamines. These small multifunctional, polyvalent metabolites enter the long Kir channel pore from the intracellular side, displacing multiple occupant ions as they migrate to a stable binding site in the transmembrane region of the channel. Numerous structure-function studies have revealed structural elements of Kir channels that determine their susceptibility to polyamine block, and enable the steep voltage dependence of this process. In addition, various channelopathies have been described that result from alteration of the polyamine sensitivity or activity of strongly rectifying channels. The primary focus of this article is to summarize current knowledge of the molecular mechanisms of polyamine block, and provide some perspective on lingering uncertainties related to this physiologically important mechanism of ion channel blockade. We also briefly review some of the important and well understood physiological roles of polyamine sensitive, strongly rectifying Kir channels, primarily of the Kir2 family.
Collapse
Affiliation(s)
- Victoria A Baronas
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia Vancouver, BC, Canada
| | - Harley T Kurata
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia Vancouver, BC, Canada
| |
Collapse
|
35
|
Chin C. Gold nanoparticle-spermidine complex blocks the inward rectifier potassium channel. AMERICAN JOURNAL OF CARDIOVASCULAR DISEASE 2014; 4:34-46. [PMID: 25006531 PMCID: PMC4082228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/05/2014] [Indexed: 06/03/2023]
Abstract
A previous study showed that negatively charged gold nanoparticles block ion pores by binding to the sulfur group of the cysteine loop of the ion channel when small molecules like amine lead the nanoparticles inside the ion pore. Cells were voltage clamped at -100 mV. Subsequently a bath application of 30 μM Ach produced a current followed by the extracellular application of 100 mM spermidine and 50 nM of nanoparticle complex. Peak amplitude was then recorded. The addition of Ach (30 uM) reversed the effect, and we recorded inhibition of the peak amplitude. We also recorded electrocardiogram (EKG) and the atria effective refractory period (AERP) after treatment with the complex in the atrium of a rabbit heart in a Langendorff apparatus. Upon external application of the complex, the Ach-activated current was blocked by 48.8% ± 3.1% with 82.7% ± 3.1% reversal. In recording the EKG and the AERP after the addition of the complex including 30 mM spermidine with 50 nM nanoparticles, the complete resolution of atrial fibrillation at 50 s and the elongation of AERP from 46 to 52 was observed, which unveils a new class 3 anti arrythmic agent using gold nanoparticles with spermidine. Negatively charged gold nanoparticles (0.8 nm) block ion pores after penetrating the cell membrane with spermidine, thus entering the cells with a polyamine transporter and acting at the intracellular face of the channel via binding to the sulfur group of the human inward rectifying potassium channel- I(KAch).
Collapse
Affiliation(s)
- Chur Chin
- Department of Internal Medicine, School of Medicine, Gyeongsang National University Chilam-dong 90, Jinju, Gyeongsangnam-d, Korea
| |
Collapse
|
36
|
Zarzoso M, Mironov S, Guerrero-Serna G, Willis BC, Pandit SV. Ventricular remodelling in rabbits with sustained high-fat diet. Acta Physiol (Oxf) 2014; 211:36-47. [PMID: 24304486 DOI: 10.1111/apha.12185] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/02/2013] [Accepted: 10/19/2013] [Indexed: 12/23/2022]
Abstract
AIM Excess weight gain and obesity are one of the most serious health problems in the western societies. These conditions enhance risk of cardiac disease and have been linked with increased prevalence for cardiac arrhythmias and sudden death. Our goal was to study the ventricular remodelling occurring in rabbits fed with high-fat diet (HFD) and its potential arrhythmogenic mechanisms. METHODS We used 15 NZW rabbits that were randomly assigned to a control (n = 7) or HFD group (n = 8) for 18 weeks. In vivo studies included blood glucose, electrocardiographic, and echocardiographic measurements. Optical mapping was performed in Langendorff-perfused isolated hearts. RESULTS Body weight (3.69 ± 0.31 vs. 2.94 ± 0.18 kg, P < 0.001) and blood glucose levels (230 ± 61 vs. 141 ± 14 mg dL(-1) , P < 0.05) were higher in the HFD group vs. controls. The rate-corrected QT interval and its dispersion were increased in HFD rabbits vs. controls (169 ± 10 vs. 146 ± 13 ms and 37 ± 11 vs. 9 ± 2 ms, respectively; P < 0.05). Echocardiographic analysis showed morphological and functional alterations in HFD rabbits indicative of left ventricle (LV) hypertrophy. Isolated heart studies revealed no changes in repolarization and propagation properties under conditions of normal extracellular K(+) , suggesting that extrinsic factors could underlie those electrocardiographic modifications. There were no differences in the dynamics of ventricular fibrillation (frequency, wave breaks) in the presence of isoproterenol. However, HFD rabbits showed a small reduction in action potential duration and an increased incidence of arrhythmias during hyperkalaemia. CONCLUSION High-fat feeding during 18 weeks in rabbits induced a type II diabetes phenotype, LV hypertrophy, abnormalities in repolarization and susceptibility to arrhythmias during hyperkalaemia.
Collapse
Affiliation(s)
- M. Zarzoso
- Center for Arrhythmia Research; University of Michigan; Ann Arbor MI USA
- Department of Physiotherapy; Universitat de València; Valencia Spain
| | - S. Mironov
- Center for Arrhythmia Research; University of Michigan; Ann Arbor MI USA
| | - G. Guerrero-Serna
- Center for Arrhythmia Research; University of Michigan; Ann Arbor MI USA
| | - B. Cicero Willis
- Center for Arrhythmia Research; University of Michigan; Ann Arbor MI USA
| | - S. V. Pandit
- Center for Arrhythmia Research; University of Michigan; Ann Arbor MI USA
| |
Collapse
|
37
|
Treuer AV, Gonzalez DR. NOS1AP modulates intracellular Ca(2+) in cardiac myocytes and is up-regulated in dystrophic cardiomyopathy. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2014; 6:37-46. [PMID: 24665357 PMCID: PMC3961100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 01/15/2014] [Indexed: 06/03/2023]
Abstract
NOS1AP gene (nitric oxide synthase 1-adaptor protein) is strongly associated with abnormalities in the QT interval of the electrocardiogram and with sudden cardiac death. To determine the role of NOS1AP in the physiology of the cardiac myocyte, we assessed the impact of silencing NOS1AP, using siRNA, on [Ca(2+)]i transients in neonatal cardiomyocytes. In addition, we examined the co-localization of NOS1AP with cardiac ion channels, and finally, evaluated the expression of NOS1AP in a mouse model of dystrophic cardiomyopathy. Using siRNA, NOS1AP levels were reduced to ~30% of the control levels (p<0.05). NOS1AP silencing in cardiac myocytes reduced significantly the amplitude of electrically evoked calcium transients (p<0.05) and the degree of S-nitrosylation of the cells (p<0.05). Using confocal microscopy, we evaluated NOS1AP subcellular location and interactions with other proteins by co-localization analysis. NOS1AP showed a high degree of co-localization with the L-type calcium channel and the inwardly rectifying potassium channel Kir3.1, a low degree of co-localization with the ryanodine receptor (RyR2) and alfa-sarcomeric actin and no co-localization with connexin 43, suggesting functionally relevant interactions with the ion channels that regulate the action potential duration. Finally, using immunofluorescence and Western blotting, we observed that in mice with dystrophic cardiomyopathy, NOS1AP was significantly up-regulated (p<0.05). These results suggest for a role of NOS1AP on cardiac arrhythmias, acting on the L-type calcium channel, and potassium channels, probably through S-nitrosylation.
Collapse
Affiliation(s)
- Adriana V Treuer
- Programa Doctorado en Ciencias Mencion Investigacion y Desarrollo de Productos Bioactivos, Instituto de Química de Recursos Naturales, Universidad de TalcaTalca, Chile
| | - Daniel R Gonzalez
- Departamento de Ciencias Basicas Biomedicas, Facultad de Ciencias de la Salud, Universidad de TalcaTalca, Chile
| |
Collapse
|
38
|
Constitutive Activity of the Acetylcholine-Activated Potassium Current IK,ACh in Cardiomyocytes. ADVANCES IN PHARMACOLOGY 2014; 70:393-409. [DOI: 10.1016/b978-0-12-417197-8.00013-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
39
|
Swale DR, Kharade SV, Denton JS. Cardiac and renal inward rectifier potassium channel pharmacology: emerging tools for integrative physiology and therapeutics. Curr Opin Pharmacol 2013; 15:7-15. [PMID: 24721648 DOI: 10.1016/j.coph.2013.11.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 11/05/2013] [Indexed: 01/01/2023]
Abstract
Inward rectifier potassium (Kir) channels play fundamental roles in cardiac and renal function and may represent unexploited drug targets for cardiovascular diseases. However, the limited pharmacology of Kir channels has slowed progress toward exploring their integrative physiology and therapeutic potential. Here, we review recent progress toward developing the small-molecule pharmacology for Kir2.x, Kir4.1, and Kir7.1 and discuss common mechanistic themes that may help guide future Kir channel-directed drug discovery efforts.
Collapse
Affiliation(s)
- Daniel R Swale
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Sujay V Kharade
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Institute for Global Health, Vanderbilt University Medical Center, Nashville, TN 37232, United States.
| |
Collapse
|
40
|
Takanari H, Nalos L, Stary-Weinzinger A, de Git KCG, Varkevisser R, Linder T, Houtman MJC, Peschar M, de Boer TP, Tidwell RR, Rook MB, Vos MA, van der Heyden MAG. Efficient and specific cardiac IK1 inhibition by a new pentamidine analogue. Cardiovasc Res 2013; 99:203-14. [DOI: 10.1093/cvr/cvt103] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
41
|
Luo X, Pan Z, Shan H, Xiao J, Sun X, Wang N, Lin H, Xiao L, Maguy A, Qi XY, Li Y, Gao X, Dong D, Zhang Y, Bai Y, Ai J, Sun L, Lu H, Luo XY, Wang Z, Lu Y, Yang B, Nattel S. MicroRNA-26 governs profibrillatory inward-rectifier potassium current changes in atrial fibrillation. J Clin Invest 2013; 123:1939-51. [PMID: 23543060 DOI: 10.1172/jci62185] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/07/2013] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is a highly prevalent arrhythmia with pronounced morbidity and mortality. Inward-rectifier K+ current (IK1) is believed to be an important regulator of reentrant-spiral dynamics and a major component of AF-related electrical remodeling. MicroRNA-26 (miR-26) is predicted to target the gene encoding KIR2.1, KCNJ2. We found that miR-26 was downregulated in atrial samples from AF animals and patients and this downregulation was accompanied by upregulation of IK1/KIR2.1 protein. miR-26 overexpression suppressed expression of KCNJ2/KIR2.1. In contrast, miR-26 knockdown, inhibition, or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-26 target. Knockdown of endogenous miR-26 promoted AF in mice, whereas adenovirus-mediated expression of miR-26 reduced AF vulnerability. Kcnj2-specific miR-masks eliminated miR-26-mediated reductions in Kcnj2, abolishing miR-26's protective effects, while coinjection of a Kcnj2-specific miR-mimic prevented miR-26 knockdown-associated AF in mice. Nuclear factor of activated T cells (NFAT), a known actor in AF-associated remodeling, was found to negatively regulate miR-26 transcription. Our results demonstrate that miR-26 controls the expression of KCNJ2 and suggest that this downregulation may promote AF.
Collapse
Affiliation(s)
- Xiaobin Luo
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Ponce-Balbuena D, Rodríguez-Menchaca AA, López-Izquierdo A, Ferrer T, Kurata HT, Nichols CG, Sánchez-Chapula JA. Molecular mechanisms of chloroquine inhibition of heterologously expressed Kir6.2/SUR2A channels. Mol Pharmacol 2012; 82:803-13. [PMID: 22851715 DOI: 10.1124/mol.112.079152] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Chloroquine and related compounds can inhibit inwardly rectifying potassium channels by multiple potential mechanisms, including pore block and allosteric effects on channel gating. Motivated by reports that chloroquine inhibition of cardiac ATP-sensitive inward rectifier K(+) current (I(KATP)) is antifibrillatory in rabbit ventricle, we investigated the mechanism of chloroquine inhibition of ATP-sensitive potassium (K(ATP)) channels (Kir6.2/SUR2A) expressed in human embryonic kidney 293 cells, using inside-out patch-clamp recordings. We found that chloroquine inhibits the Kir6.2/SUR2A channel by interacting with at least two different sites and by two mechanisms of action. A fast-onset effect is observed at depolarized membrane voltages and enhanced by the N160D mutation in the central cavity, probably reflecting direct channel block resulting from the drug entering the channel pore from the cytoplasmic side. Conversely, a slow-onset, voltage-independent inhibition of I(KATP) is regulated by chloroquine interaction with a different site and probably involves disruption of interactions between Kir6.2/SUR2A and phosphatidylinositol 4,5-bisphosphate. Our findings reveal multiple mechanisms of K(ATP) channel inhibition by chloroquine, highlighting the numerous convergent regulatory mechanisms of these ligand-dependent ion channels.
Collapse
Affiliation(s)
- Daniela Ponce-Balbuena
- Unidad de Investigación Carlos Méndez del Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, México
| | | | | | | | | | | | | |
Collapse
|
43
|
Filgueiras-Rama D, Castrejón S, Estrada A, Doiny D, Ortega M, Calvo C, Berenfeld O, Jalife J, Merino JL. [Basic mechanisms of the new antiarrhythmic drugs in atrial fibrillation]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2012; 82:139-152. [PMID: 22735655 PMCID: PMC5576579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia seen in clinical practice. Despite of new technological breakthroughs and the understanding of the mechanisms underlying AF, based on animal models and ablation procedures in patients, the antiarrhythmic drugs remain the main therapeutic strategy to restore and maintain the sinus rhythm. New antiarrhythmic drugs are already available in the clinical practice and many others are under development. The new antiarrhythmic drugs have the capability to block atrial-specific ionic currents, which are involved in the maintenance of the arrhythmia. Parallel, increasing evidence supports the use of compounds to regulate the arrhythmogenic atrial substrate involved in the long-term maintenance of the arrhythmia (upstream therapies). This article reviews the new antiarrhythmic drugs and upstream therapies, based on the current knowledge of the mechanisms involved in the maintenance of AF.
Collapse
Affiliation(s)
- David Filgueiras-Rama
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan. Ann Arbor, Michigan, USA
| | - Sergio Castrejón
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
| | - Alejandro Estrada
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
| | - David Doiny
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
| | - Marta Ortega
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
| | - Conrado Calvo
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan. Ann Arbor, Michigan, USA
| | - Omer Berenfeld
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan. Ann Arbor, Michigan, USA
| | - Jose Jalife
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan. Ann Arbor, Michigan, USA
| | - Jose L. Merino
- Unidad de Arritmias y Electrofisiología Cardiaca Robotizada. Departamento de Cardiología. Hospital Universitario La Paz. Madrid. Spain
| |
Collapse
|
44
|
Abstract
Atrial fibrillation is the most common type of cardiac arrhythmia, and is responsible for substantial morbidity and mortality in the general population. Current treatments have moderate efficacy and considerable risks, especially of pro-arrhythmia, highlighting the need for new therapeutic strategies. In recent years, substantial efforts have been invested in developing novel treatments that target the underlying molecular determinants of atrial fibrillation, and several new compounds are under development. This Review focuses on the mechanistic rationale for the development of new anti-atrial fibrillation drugs, on the molecular and structural motifs that they target and on the results obtained so far in experimental and clinical studies.
Collapse
|
45
|
Filgueiras-Rama D, Martins RP, Mironov S, Yamazaki M, Calvo CJ, Ennis SR, Bandaru K, Noujaim SF, Kalifa J, Berenfeld O, Jalife J. Chloroquine terminates stretch-induced atrial fibrillation more effectively than flecainide in the sheep heart. Circ Arrhythm Electrophysiol 2012; 5:561-70. [PMID: 22467674 DOI: 10.1161/circep.111.966820] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Blockade of inward-rectifier K+ channels by chloroquine terminates reentry in cholinergic atrial fibrillation (AF). However, it is unknown whether inward-rectifier K+ channels and reentry are also important in maintaining stretch-induced AF (SAF). We surmised that reentry underlies SAF, and that abolishing reentry with chloroquine terminates SAF more effectively than traditional Na+-channel blockade by flecainide. METHODS AND RESULTS Thirty Langendorff-perfused sheep hearts were exposed to acute and continuous atrial stretch, and mapped optically and electrically. AF dynamics were studied under control and during perfusion of either chloroquine (4 µmol/L, n=7) or flecainide (2-4 µmol/L, n=5). Chloroquine increased rotor core size and decreased reentry frequency from 10.6±0.7 Hz in control to 6.3±0.7 Hz (P<0.005) just before restoring sinus rhythm (7/7). Flecainide had lesser effects on core size and reentry frequency than chloroquine and did not restore sinus rhythm (0/5). Specific IKr blockade by E-4031 (n=7) did not terminate AF when frequency values were >8 Hz. During pacing (n=11), flecainide reversibly reduced conduction velocity (≈30% at cycle length 300, 250, and 200 ms; P<0.05) to a larger extent than chloroquine (11% to 19%; cycle length, 300, 250, and 200 ms; P<0.05). Significant action potential duration prolongation was demonstrable only for chloroquine at cycle length 300 (12%) and cycle length 250 ms (9%) (P<0.05). CONCLUSIONS Chloroquine is more effective than flecainide in terminating SAF in isolated sheep hearts by significantly increasing core size and decreasing reentry frequency. Chloroquine's effectiveness may be explained by its inward-rectifier K+ channel blockade profile and suggest that reentry is important to maintain acute SAF.
Collapse
Affiliation(s)
- David Filgueiras-Rama
- Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48108, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Mechanisms for Kir channel inhibition by quinacrine: acute pore block of Kir2.x channels and interference in PIP2 interaction with Kir2.x and Kir6.2 channels. Pflugers Arch 2011; 462:505-17. [DOI: 10.1007/s00424-011-0995-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 10/18/2022]
|
47
|
van der Heyden MAG, Sánchez-Chapula JA. Toward specific cardiac I(K1) modulators for in vivo application: old drugs point the way. Heart Rhythm 2011; 8:1076-80. [PMID: 21296684 DOI: 10.1016/j.hrthm.2011.01.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 01/26/2011] [Indexed: 10/18/2022]
Affiliation(s)
- Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands.
| | | |
Collapse
|
48
|
Noujaim SF, Stuckey JA, Ponce-Balbuena D, Ferrer-Villada T, López-Izquierdo A, Pandit SV, Sánchez-Chapula JA, Jalife J. Structural bases for the different anti-fibrillatory effects of chloroquine and quinidine. Cardiovasc Res 2011; 89:862-9. [PMID: 21233253 DOI: 10.1093/cvr/cvr008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Chloroquine, an anti-malarial quinoline, is structurally similar to quinidine. Both drugs have been shown to block ion channels. We tested the hypothesis that chloroquine's mode of interaction with the vestibule of the cytoplasmic domain of the inward rectifier potassium channel Kir2.1 makes it a more effective I(K1) blocker and anti-fibrillatory agent than quinidine. METHODS AND RESULTS We used comparative molecular modelling and ligand docking of the three-dimensional structures of quinidine and chloroquine in the intracellular domain of Kir2.1. Simulations predicted that chloroquine effectively blocks potassium flow by binding at the centre of the ion permeation vestibule of Kir2.1. In contrast, quinidine binds the vestibular side, only partially blocking ion movement. We tested the modelling predictions in Kir2.1-expressing human embryonic kidney (HEK)-293 cells. The half-maximal inhibitory concentration for chloroquine block of I(K1) was 1.2 µM, while that of quinidine was 57 µM. Finally, we used optical mapping of Langendorff-perfused mouse hearts with cardiac-specific Kir2.1 up-regulation to compare the anti-fibrillatory effects of the drugs. In five of six hearts, 10 μM quinidine slowed the frequency but did not terminate the tachyarrhythmia. In five of five hearts, 10 μM chloroquine terminated the arrhythmia, restoring sinus rhythm. CONCLUSION Quinidine only partially blocks I(K1). Chloroquine binds at the centre of the ion permeation vestibule of Kir2.1, which makes it a more effective I(K1) blocker and anti-fibrillatory agent than quinidine. Integrating the structural biology of drug-ion channel interactions with cellular electrophysiology and optical mapping is an excellent approach to understand the molecular mechanisms of anti-arrhythmic drug action and for drug discovery.
Collapse
Affiliation(s)
- Sami F Noujaim
- Center for Arrhythmia Research, University of Michigan, 5025 Venture Dr., Ann Arbor, MI 48108, USA
| | | | | | | | | | | | | | | |
Collapse
|