1
|
Fitts RH, Wang X, Kwok WM, Camara AKS. Cardiomyocyte Adaptation to Exercise: K+ Channels, Contractility and Ischemic Injury. Int J Sports Med 2024. [PMID: 38648799 DOI: 10.1055/a-2296-7604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Cardiovascular disease is a leading cause of morbidity and mortality, and exercise-training (TRN) is known to reduce risk factors and protect the heart from ischemia and reperfusion injury. Though the cardioprotective effects of exercise are well-documented, underlying mechanisms are not well understood. This review highlights recent findings and focuses on cardiac factors with emphasis on K+ channel control of the action potential duration (APD), β-adrenergic and adenosine regulation of cardiomyocyte function, and mitochondrial Ca2+ regulation. TRN-induced prolongation and shortening of the APD at low and high activation rates, respectively, is discussed in the context of a reduced response of the sarcolemma delayed rectifier potassium channel (IK) and increased content and activation of the sarcolemma KATP channel. A proposed mechanism underlying the latter is presented, including the phosphatidylinositol-3kinase/protein kinase B pathway. TRN induced increases in cardiomyocyte contractility and the response to adrenergic agonists are discussed. The TRN-induced protection from reperfusion injury is highlighted by the increased content and activation of the sarcolemma KATP channel and the increased phosphorylated glycogen synthase kinase-3β, which aid in preventing mitochondrial Ca2+ overload and mitochondria-triggered apoptosis. Finally, a brief section is presented on the increased incidences of atrial fibrillation associated with age and in life-long exercisers.
Collapse
Affiliation(s)
- Robert H Fitts
- Biological Sciences, Marquette University, Milwaukee, United States
| | - Xinrui Wang
- Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, United States
| | - Wai-Meng Kwok
- Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, United States
- Anesthesiology, Medical College of Wisconsin, Milwaukee, United States
- Cancer Center, Medical College of Wisconsin, Milwaukee, United States
| | - Amadou K S Camara
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, United States
- Anesthesiology, Medical College of Wisconsin, Milwaukee, United States
- Cancer Center, Medical College of Wisconsin, Milwaukee, United States
- Physiology, Medical College of Wisconsin, Milwaukee, United States
| |
Collapse
|
2
|
Gando I, Becerra Flores M, Chen IS, Yang HQ, Nakamura TY, Cardozo TJ, Coetzee WA. CL-705G: a novel chemical Kir6.2-specific K ATP channel opener. Front Pharmacol 2023; 14:1197257. [PMID: 37408765 PMCID: PMC10319115 DOI: 10.3389/fphar.2023.1197257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023] Open
Abstract
Background: KATP channels have diverse roles, including regulation of insulin secretion and blood flow, and protection against biological stress responses and are excellent therapeutic targets. Different subclasses of KATP channels exist in various tissue types due to the unique assemblies of specific pore-forming (Kir6.x) and accessory (SURx) subunits. The majority of pharmacological openers and blockers act by binding to SURx and are poorly selective against the various KATP channel subclasses. Methods and Results: We used 3D models of the Kir6.2/SUR homotetramers based on existing cryo-EM structures of channels in both the open and closed states to identify a potential agonist binding pocket in a functionally critical area of the channel. Computational docking screens of this pocket with the Chembridge Core chemical library of 492,000 drug-like compounds yielded 15 top-ranked "hits", which were tested for activity against KATP channels using patch clamping and thallium (Tl+) flux assays with a Kir6.2/SUR2A HEK-293 stable cell line. Several of the compounds increased Tl+ fluxes. One of them (CL-705G) opened Kir6.2/SUR2A channels with a similar potency as pinacidil (EC50 of 9 µM and 11 μM, respectively). Remarkably, compound CL-705G had no or minimal effects on other Kir channels, including Kir6.1/SUR2B, Kir2.1, or Kir3.1/Kir3.4 channels, or Na+ currents of TE671 medulloblastoma cells. CL-705G activated Kir6.2Δ36 in the presence of SUR2A, but not when expressed by itself. CL-705G activated Kir6.2/SUR2A channels even after PIP2 depletion. The compound has cardioprotective effects in a cellular model of pharmacological preconditioning. It also partially rescued activity of the gating-defective Kir6.2-R301C mutant that is associated with congenital hyperinsulinism. Conclusion: CL-705G is a new Kir6.2 opener with little cross-reactivity with other channels tested, including the structurally similar Kir6.1. This, to our knowledge, is the first Kir-specific channel opener.
Collapse
Affiliation(s)
- Ivan Gando
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - Manuel Becerra Flores
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - I.-Shan Chen
- Phamacology, Wakayama Medical University, Wakayama, Japan
| | - Hua-Qian Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, China
| | | | - Timothy J. Cardozo
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - William A. Coetzee
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| |
Collapse
|
3
|
Premont A, Saadeh K, Edling C, Lewis R, Marr CM, Jeevaratnam K. Cardiac ion channel expression in the equine model - In-silico prediction utilising RNA sequencing data from mixed tissue samples. Physiol Rep 2022; 10:e15273. [PMID: 35880716 PMCID: PMC9316921 DOI: 10.14814/phy2.15273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/19/2022] [Accepted: 04/03/2022] [Indexed: 06/15/2023] Open
Abstract
Understanding cardiomyocyte ion channel expression is crucial to understanding normal cardiac electrophysiology and underlying mechanisms of cardiac pathologies particularly arrhythmias. Hitherto, equine cardiac ion channel expression has rarely been investigated. Therefore, we aim to predict equine cardiac ion channel gene expression. Raw RNAseq data from normal horses from 9 datasets was retrieved from ArrayExpress and European Nucleotide Archive and reanalysed. The normalised (FPKM) read counts for a gene in a mix of tissue were hypothesised to be the average of the expected expression in each tissue weighted by the proportion of the tissue in the mix. The cardiac-specific expression was predicted by estimating the mean expression in each other tissues. To evaluate the performance of the model, predicted gene expression values were compared to the human cardiac gene expression. Cardiac-specific expression could be predicted for 91 ion channels including most expressed Na+ channels, K+ channels and Ca2+ -handling proteins. These revealed interesting differences from what would be expected based on human studies. These differences included predominance of NaV 1.4 rather than NaV 1.5 channel, and RYR1, SERCA1 and CASQ1 rather than RYR2, SERCA2, CASQ2 Ca2+ -handling proteins. Differences in channel expression not only implicate potentially different regulatory mechanisms but also pathological mechanisms of arrhythmogenesis.
Collapse
Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Khalil Saadeh
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
- School of Clinical MedicineUniversity of CambridgeCambridgeUK
| | - Charlotte Edling
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Rebecca Lewis
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Celia M. Marr
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
- School of Clinical MedicineUniversity of CambridgeCambridgeUK
- Rossdales Equine Hospital and Diagnostic CentreExningSuffolkUK
| | | |
Collapse
|
4
|
Yang HQ, Echeverry FA, ElSheikh A, Gando I, Anez Arredondo S, Samper N, Cardozo T, Delmar M, Shyng SL, Coetzee WA. Subcellular trafficking and endocytic recycling of K ATP channels. Am J Physiol Cell Physiol 2022; 322:C1230-C1247. [PMID: 35508187 PMCID: PMC9169827 DOI: 10.1152/ajpcell.00099.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/27/2022] [Accepted: 04/30/2022] [Indexed: 11/22/2022]
Abstract
Sarcolemmal/plasmalemmal ATP-sensitive K+ (KATP) channels have key roles in many cell types and tissues. Hundreds of studies have described how the KATP channel activity and ATP sensitivity can be regulated by changes in the cellular metabolic state, by receptor signaling pathways and by pharmacological interventions. These alterations in channel activity directly translate to alterations in cell or tissue function, that can range from modulating secretory responses, such as insulin release from pancreatic β-cells or neurotransmitters from neurons, to modulating contractile behavior of smooth muscle or cardiac cells to elicit alterations in blood flow or cardiac contractility. It is increasingly becoming apparent, however, that KATP channels are regulated beyond changes in their activity. Recent studies have highlighted that KATP channel surface expression is a tightly regulated process with similar implications in health and disease. The surface expression of KATP channels is finely balanced by several trafficking steps including synthesis, assembly, anterograde trafficking, membrane anchoring, endocytosis, endocytic recycling, and degradation. This review aims to summarize the physiological and pathophysiological implications of KATP channel trafficking and mechanisms that regulate KATP channel trafficking. A better understanding of this topic has potential to identify new approaches to develop therapeutically useful drugs to treat KATP channel-related diseases.
Collapse
Affiliation(s)
- Hua-Qian Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China
| | | | - Assmaa ElSheikh
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
- Department of Medical Biochemistry, Tanta University, Tanta, Egypt
| | - Ivan Gando
- Department of Pathology, NYU School of Medicine, New York, New York
| | | | - Natalie Samper
- Department of Pathology, NYU School of Medicine, New York, New York
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - Mario Delmar
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
- Department of Medicine, NYU School of Medicine, New York, New York
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
| | - William A Coetzee
- Department of Pathology, NYU School of Medicine, New York, New York
- Department of Neuroscience & Physiology, NYU School of Medicine, New York, New York
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| |
Collapse
|
5
|
Thijssen DHJ, Uthman L, Somani Y, van Royen N. Short-term exercise-induced protection of cardiovascular function and health: why and how fast does the heart benefit from exercise? J Physiol 2022; 600:1339-1355. [PMID: 35239189 PMCID: PMC9311195 DOI: 10.1113/jp282000#support-information-section] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 12/10/2021] [Indexed: 05/28/2023] Open
Abstract
Regular exercise training has potent and powerful protective effects against the development of cardiovascular disease. These cardioprotective effects of regular exercise training are partly explained through the effects of exercise on traditional cardiovascular risk factors and improvement in cardiac and vascular health, which take several weeks to months to develop. This review focuses on the observation that single bouts of exercise may also possess an underrecognized, clinically useful form of immediate cardioprotection. Studies, performed in both animals and humans, demonstrate that single or short-term exercise-induced protection (SEP) attenuates the magnitude of cardiac and/or vascular damage in response to prolonged ischaemia and reperfusion injury. This review highlights preclinical evidence supporting the hypothesis that SEP activates multiple pathways to confer immediate protection against ischaemic events, reduce the severity of potentially lethal ischaemic myocardial injury, and therefore act as a physiological first line of defence against injury. Given the fact that the extent of SEP could be modulated by exercise-related and subject-related factors, it is important to recognize and consider these factors to optimize future clinical implications of SEP. This review also summarizes potential effector signalling pathways (i.e. communication between exercising muscles to vascular/cardiac tissue) and intracellular pathways (i.e. reducing tissue damage) that ultimately confer protection against cardiac and vascular injury. Finally, we discuss potential future directions for designing adequate human and animal studies that will support developing effective SEP strategies for the (multi-)diseased and aged individual. KEY POINTS: Single or short-term exercise-induced protection (SEP) attenuates the magnitude of cardiac and/or vascular damage in response to prolonged ischaemia and reperfusion injury (IR injury). SEP activates multiple pathways to confer cardiac protection, which develops remotely at the site of the activated muscle by release of circulating molecules, which transfer towards activation of intramyocardial signalling that promotes cell survival during episodes of IR injury. SEP represents an attractive intervention in aged individuals and in those with co-morbidities. The immediate protection, low cost and simplicity to increase the 'dose' of SEP offers unique opportunities in the clinical applications of SEP.
Collapse
Affiliation(s)
- Dick H. J. Thijssen
- Radboud Institute for Health SciencesDepartments of PhysiologyNijmegenThe Netherlands
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLeicesterUK
| | - Laween Uthman
- Radboud Institute for Health SciencesDepartments of PhysiologyNijmegenThe Netherlands
- CardiologyRadboud University Medical CenterNijmegenThe Netherlands
| | - Yasina Somani
- Research Institute for Sport and Exercise SciencesLiverpool John Moores UniversityLeicesterUK
| | - Niels van Royen
- CardiologyRadboud University Medical CenterNijmegenThe Netherlands
| |
Collapse
|
6
|
Thijssen DHJ, Uthman L, Somani Y, Royen N. Short term exercise‐induced protection of cardiovascular function and health: Why and how fast does the heart benefit from exercise? J Physiol 2021; 600:1339-1355. [PMID: 35239189 PMCID: PMC9311195 DOI: 10.1113/jp282000] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 12/10/2021] [Indexed: 11/13/2022] Open
Abstract
Abstract Regular exercise training has potent and powerful protective effects against the development of cardiovascular disease. These cardioprotective effects of regular exercise training are partly explained through the effects of exercise on traditional cardiovascular risk factors and improvement in cardiac and vascular health, which take several weeks to months to develop. This review focuses on the observation that single bouts of exercise may also possess an underrecognized, clinically useful form of immediate cardioprotection. Studies, performed in both animals and humans, demonstrate that single or short‐term exercise‐induced protection (SEP) attenuates the magnitude of cardiac and/or vascular damage in response to prolonged ischaemia and reperfusion injury. This review highlights preclinical evidence supporting the hypothesis that SEP activates multiple pathways to confer immediate protection against ischaemic events, reduce the severity of potentially lethal ischaemic myocardial injury, and therefore act as a physiological first line of defence against injury. Given the fact that the extent of SEP could be modulated by exercise‐related and subject‐related factors, it is important to recognize and consider these factors to optimize future clinical implications of SEP. This review also summarizes potential effector signalling pathways (i.e. communication between exercising muscles to vascular/cardiac tissue) and intracellular pathways (i.e. reducing tissue damage) that ultimately confer protection against cardiac and vascular injury. Finally, we discuss potential future directions for designing adequate human and animal studies that will support developing effective SEP strategies for the (multi‐)diseased and aged individual. Key points Single or short‐term exercise‐induced protection (SEP) attenuates the magnitude of cardiac and/or vascular damage in response to prolonged ischaemia and reperfusion injury (IR injury). SEP activates multiple pathways to confer cardiac protection, which develops remotely at the site of the activated muscle by release of circulating molecules, which transfer towards activation of intramyocardial signalling that promotes cell survival during episodes of IR injury. SEP represents an attractive intervention in aged individuals and in those with co‐morbidities. The immediate protection, low cost and simplicity to increase the ‘dose’ of SEP offers unique opportunities in the clinical applications of SEP.
![]()
Collapse
Affiliation(s)
- Dick H. J. Thijssen
- Radboud Institute for Health Sciences Departments of Physiology Nijmegen The Netherlands
- Research Institute for Sport and Exercise Sciences Liverpool John Moores University Leicester United Kingdom
| | - Laween Uthman
- Radboud Institute for Health Sciences Departments of Physiology Nijmegen The Netherlands
- Cardiology Radboud University Medical Center Nijmegen The Netherlands
| | - Yasina Somani
- Research Institute for Sport and Exercise Sciences Liverpool John Moores University Leicester United Kingdom
| | - Niels Royen
- Cardiology Radboud University Medical Center Nijmegen The Netherlands
| |
Collapse
|
7
|
Swift LM, Kay MW, Ripplinger CM, Posnack NG. Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research. Am J Physiol Heart Circ Physiol 2021; 321:H1005-H1013. [PMID: 34623183 DOI: 10.1152/ajpheart.00477.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Optical mapping is an imaging technique that is extensively used in cardiovascular research, wherein parameter-sensitive fluorescent indicators are used to study the electrophysiology and excitation-contraction coupling of cardiac tissues. Despite many benefits of optical mapping, eliminating motion artifacts within the optical signals is a major challenge, as myocardial contraction interferes with the faithful acquisition of action potentials and intracellular calcium transients. As such, excitation-contraction uncoupling agents are frequently used to reduce signal distortion by suppressing contraction. When compared with other uncoupling agents, blebbistatin is the most frequently used, as it offers increased potency with minimal direct effects on cardiac electrophysiology. Nevertheless, blebbistatin may exert secondary effects on electrical activity, metabolism, and coronary flow, and the incorrect administration of blebbistatin to cardiac tissue can prove detrimental, resulting in erroneous interpretation of optical mapping results. In this "Getting It Right" perspective, we briefly review the literature regarding the use of blebbistatin in cardiac optical mapping experiments, highlight potential secondary effects of blebbistatin on cardiac electrical activity and metabolic demand, and conclude with the consensus of the authors on best practices for effectively using blebbistatin in optical mapping studies of cardiac tissue.
Collapse
Affiliation(s)
- Luther M Swift
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | | | - Nikki Gillum Posnack
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia.,Department of Pediatrics, George Washington University, Washington, District of Columbia.,Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
| |
Collapse
|
8
|
Dantas PS, Guzzoni V, Perez JD, Arita DY, Novaes PD, Marcondes FK, Casarini DE, Cunha TS. Nandrolone combined with strenuous resistance training impairs myocardial proteome profile of rats. Steroids 2021; 175:108916. [PMID: 34492258 DOI: 10.1016/j.steroids.2021.108916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 08/02/2021] [Accepted: 08/30/2021] [Indexed: 12/25/2022]
Abstract
We aimed to investigate the effects of high doses of nandrolone decanoate and resistance training (RT) on the proteomic profile of the left ventricle (LV) of rats, using a label-free quantitative approach. Male rats were randomized into four groups: untrained vehicle (UTV), trained vehicle (TV), untrained nandrolone (UTN), and trained nandrolone (TN). Rats were familiarized with the exercise training protocol (jump exercise) for one week. Jump-exercise was performed five days a week for 6 weeks, with 30 s of inter-set rest intervals. Nandrolone was administrated for 6 weeks (5 mg/kg, twice a week, via intramuscular). Systolic and diastolic arterial pressure and heart rate were measured 48 h post-training. LV was isolated and collagen content was measured. The expression of cardiac proteins was analyzed by ultra-efficiency liquid chromatography with mass spectrometry high / low collision energy (UPLC/MSE). Nandrolone and RT led to cardiac hypertrophy, even though high doses of nandrolone counteracted the RT-induced arterial pressures lowering. Nandrolone also affected the proteome profile negatively in LV of rats, including critical proteins related to biological processes (metabolism, oxidative stress, inflammation), structural function and membrane transporters. Our findings show physiological relevance since high doses of nandrolone induced detrimental effects on the proteome profile of heart tissue and hemodynamic parameters of rats. Furthermore, as nandrolone abuse has become increasingly common among recreational athletes and casual fitness enthusiasts, we consider that our findings have clinical relevance as well.
Collapse
Affiliation(s)
- Patrícia Sousa Dantas
- Federal University of São Paulo (UNIFESP), Department of Medicine, Nephrology Division, São Paulo, São Paulo, Brazil
| | - Vinicius Guzzoni
- Federal University of São Paulo (UNIFESP), Institute of Science and Technology, Department of Science and Technology, São José dos Campos, São Paulo, Brazil
| | - Juliana Dinéia Perez
- Federal University of São Paulo (UNIFESP), Department of Medicine, Nephrology Division, São Paulo, São Paulo, Brazil
| | - Danielle Yuri Arita
- Federal University of São Paulo (UNIFESP), Department of Medicine, Nephrology Division, São Paulo, São Paulo, Brazil
| | - Pedro Duarte Novaes
- Piracicaba Dental School, Department of Morphology, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Fernanda Klein Marcondes
- Piracicaba Dental School, Department of Physiological Sciences, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Dulce Elena Casarini
- Federal University of São Paulo (UNIFESP), Department of Medicine, Nephrology Division, São Paulo, São Paulo, Brazil
| | - Tatiana Sousa Cunha
- Federal University of São Paulo (UNIFESP), Institute of Science and Technology, Department of Science and Technology, São José dos Campos, São Paulo, Brazil.
| |
Collapse
|
9
|
Sanchis-Gomar F, Lavie CJ, Marín J, Perez-Quilis C, Eijsvogels TMH, O'Keefe JH, Perez MV, Blair SN. Exercise Effects On Cardiovascular Disease: From Basic Aspects To Clinical Evidence. Cardiovasc Res 2021; 118:2253-2266. [PMID: 34478520 DOI: 10.1093/cvr/cvab272] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 08/31/2021] [Indexed: 12/16/2022] Open
Abstract
Cardiovascular (CV) disease (CVD) remains the leading cause of major morbidity and CVD- and all-cause mortality in most of the world. It is now clear that regular physical activity (PA) and exercise training (ET) induces a wide range of direct and indirect physiologic adaptations and pleiotropic benefits for human general and CV health. Generally, higher levels of PA, ET, and cardiorespiratory fitness (CRF) are correlated with reduced risk of CVD, including myocardial infarction, CVD-related death, and all-cause mortality. Although exact details regarding the ideal doses of ET, including resistance and, especially, aerobic ET, as well as the potential adverse effects of extreme levels of ET, continue to be investigated, there is no question that most of the world's population have insufficient levels of PA/ET, and many also have lower than ideal levels of CRF. Therefore, assessment and promotion of PA, ET, and efforts to improve levels of CRF should be integrated into all health professionals' practices worldwide. In this state-of-the-art review, we discuss the exercise effects on many areas related to CVD, from basic aspects to clinical practice.
Collapse
Affiliation(s)
- Fabian Sanchis-Gomar
- Department of Physiology, Faculty of Medicine, University of Valencia and INCLIVA Biomedical Research Institute, Valencia, Spain.,Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Carl J Lavie
- John Ochsner Heart and Vascular Institute, Ochsner Clinical School, The University of Queensland School of Medicine, New Orleans, LA, USA
| | - Jorge Marín
- Growth, Exercise, Nutrition and Development Group, Faculty of Health and Sport Sciences, University of Zaragoza, Zaragoza, Spain
| | - Carme Perez-Quilis
- Department of Physiology, Faculty of Medicine, University of Valencia and INCLIVA Biomedical Research Institute, Valencia, Spain
| | - Thijs M H Eijsvogels
- Radboud Institute for Health Science, Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - James H O'Keefe
- St. Luke's Mid America Heart Institute, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - Marco V Perez
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Steven N Blair
- Department of Exercise Sciences, University of South Carolina, Columbia, USA
| |
Collapse
|
10
|
Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
Collapse
|
11
|
Genetic Polymorphisms Related to VO2max Adaptation Are Associated With Elite Rugby Union Status and Competitive Marathon Performance. Int J Sports Physiol Perform 2021; 16:1858-1864. [PMID: 34088882 DOI: 10.1123/ijspp.2020-0856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/19/2021] [Accepted: 03/23/2021] [Indexed: 11/18/2022]
Abstract
PURPOSE Genetic polymorphisms have been associated with the adaptation to training in maximal oxygen uptake (V˙O2max). However, the genotype distribution of selected polymorphisms in athletic cohorts is unknown, with their influence on performance characteristics also undetermined. This study investigated whether the genotype distributions of 3 polymorphisms previously associated with V˙O2max training adaptation are associated with elite athlete status and performance characteristics in runners and rugby athletes, competitors for whom aerobic metabolism is important. METHODS Genomic DNA was collected from 732 men including 165 long-distance runners, 212 elite rugby union athletes, and 355 nonathletes. Genotype and allele frequencies of PRDM1 rs10499043 C/T, GRIN3A rs1535628 G/A, and KCNH8 rs4973706 T/C were compared between athletes and nonathletes. Personal-best marathon times in runners, as well as in-game performance variables and playing position, of rugby athletes were analyzed according to genotype. RESULTS Runners with PRDM1 T alleles recorded marathon times ∼3 minutes faster than CC homozygotes (02:27:55 [00:07:32] h vs 02:31:03 [00:08:24] h, P = .023). Rugby athletes had 1.57 times greater odds of possessing the KCNH8 TT genotype than nonathletes (65.5% vs 54.7%, χ2 = 6.494, P = .013). No other associations were identified. CONCLUSIONS This study is the first to demonstrate that polymorphisms previously associated with V˙O2max training adaptations in nonathletes are also associated with marathon performance (PRDM1) and elite rugby union status (KCNH8). The genotypes and alleles previously associated with superior endurance-training adaptation appear to be advantageous in long-distance running and achieving elite status in rugby union.
Collapse
|
12
|
Gómez-Barroso M, Moreno-Calderón KM, Sánchez-Duarte E, Cortés-Rojo C, Saavedra-Molina A, Rodríguez-Orozco AR, Montoya-Pérez R. Diazoxide and Exercise Enhance Muscle Contraction during Obesity by Decreasing ROS Levels, Lipid Peroxidation, and Improving Glutathione Redox Status. Antioxidants (Basel) 2020; 9:antiox9121232. [PMID: 33291828 PMCID: PMC7762033 DOI: 10.3390/antiox9121232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/26/2020] [Accepted: 12/02/2020] [Indexed: 12/16/2022] Open
Abstract
Obesity causes insulin resistance and hyperinsulinemia which causes skeletal muscle dysfunction resulting in a decrease in contraction force and a reduced capacity to avoid fatigue, which overall, causes an increase in oxidative stress. KATP channel openers such as diazoxide and the implementation of exercise protocols have been reported to be actively involved in protecting skeletal muscle against metabolic stress; however, the effects of diazoxide and exercise on muscle contraction and oxidative stress during obesity have not been explored. This study aimed to determine the effect of diazoxide in the contraction of skeletal muscle of obese male Wistar rats (35 mg/kg), and with an exercise protocol (five weeks) and the combination from both. Results showed that the treatment with diazoxide and exercise improved muscular contraction, showing an increase in maximum tension and total tension due to decreased ROS and lipid peroxidation levels and improved glutathione redox state. Therefore, these results suggest that diazoxide and exercise improve muscle function during obesity, possibly through its effects as KATP channel openers.
Collapse
Affiliation(s)
- Mariana Gómez-Barroso
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Múgica S/N, Col. Felicitas del Río, Morelia, Michoacán 58030, Mexico; (M.G.-B.); (K.M.M.-C.); (C.C.-R.); (A.S.-M.)
| | - Koré M. Moreno-Calderón
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Múgica S/N, Col. Felicitas del Río, Morelia, Michoacán 58030, Mexico; (M.G.-B.); (K.M.M.-C.); (C.C.-R.); (A.S.-M.)
| | - Elizabeth Sánchez-Duarte
- Departamento de Ciencias Aplicadas al Trabajo, Universidad de Guanajuato Campus León, Eugenio Garza Sada 572, Lomas del Campestre Sección 2, León, Guanajuato 37150, Mexico;
| | - Christian Cortés-Rojo
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Múgica S/N, Col. Felicitas del Río, Morelia, Michoacán 58030, Mexico; (M.G.-B.); (K.M.M.-C.); (C.C.-R.); (A.S.-M.)
| | - Alfredo Saavedra-Molina
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Múgica S/N, Col. Felicitas del Río, Morelia, Michoacán 58030, Mexico; (M.G.-B.); (K.M.M.-C.); (C.C.-R.); (A.S.-M.)
| | - Alain R. Rodríguez-Orozco
- Facultad de Ciencias Médicas y Biológicas “Dr. Ignacio Chávez”, Universidad Michoacana de San Nicolás de Hidalgo Av. Dr. Rafael Carrillo S/N, Esq. Dr. Salvador González Herrejón, Bosque Cuauhtémoc, Morelia, Michoacán 58020, Mexico;
| | - Rocío Montoya-Pérez
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Múgica S/N, Col. Felicitas del Río, Morelia, Michoacán 58030, Mexico; (M.G.-B.); (K.M.M.-C.); (C.C.-R.); (A.S.-M.)
- Correspondence:
| |
Collapse
|
13
|
Moreira JBN, Wohlwend M, Wisløff U. Exercise and cardiac health: physiological and molecular insights. Nat Metab 2020; 2:829-839. [PMID: 32807982 DOI: 10.1038/s42255-020-0262-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/13/2020] [Indexed: 12/19/2022]
Abstract
The cardiac benefits of exercise have been recognized for centuries. Studies have undisputedly shown that regular exercise is beneficial for the cardiovascular system in young, old, healthy and diseased populations. For these reasons, physical activity has been recommended worldwide for cardiovascular disease prevention and treatment. Although the benefits of exercise are clear, understanding of the molecular triggers that orchestrate these effects remains incomplete and has been a topic of intense research in recent years. Here, we provide a comprehensive review of the cardiac effects of physical activity, beginning with a brief history of exercise in cardiovascular medicine and then discussing seminal work on the physiological effects of exercise in healthy, diseased and aged hearts. Later, we revisit pioneering work on the molecular mechanisms underlying the cardiac benefits of exercise, and we conclude with our view on the translational potential of this knowledge as a powerful platform for cardiovascular disease drug discovery.
Collapse
Affiliation(s)
- Jose B N Moreira
- Cardiac Exercise Research Group at the Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Martin Wohlwend
- Cardiac Exercise Research Group at the Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ulrik Wisløff
- Cardiac Exercise Research Group at the Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway.
- School of Human Movement & Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia.
| |
Collapse
|
14
|
Penna C, Alloatti G, Crisafulli A. Mechanisms Involved in Cardioprotection Induced by Physical Exercise. Antioxid Redox Signal 2020; 32:1115-1134. [PMID: 31892282 DOI: 10.1089/ars.2019.8009] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Significance: Regular exercise training can reduce myocardial damage caused by acute ischemia/reperfusion (I/R). Exercise can reproduce the phenomenon of ischemic preconditioning, due to the capacity of brief periods of ischemia to reduce myocardial damage caused by acute I/R. In addition, exercise may also activate the multiple kinase cascade responsible for cardioprotection even in the absence of ischemia. Recent Advances: Animal and human studies highlighted the fact that, besides to reduce risk factors related to cardiovascular disease, the beneficial effects of exercise are also due to its ability to induce conditioning of the heart. Exercise behaves as a physiological stress that triggers beneficial adaptive cellular responses, inducing a protective phenotype in the heart. The factors contributing to the exercise-induced heart preconditioning include stimulation of the anti-radical defense system and nitric oxide production, opioids, myokines, and adenosine-5'-triphosphate (ATP) dependent potassium channels. They appear to be also involved in the protective effect exerted by exercise against cardiotoxicity related to chemotherapy. Critical Issues and Future Directions: Although several experimental evidences on the protective effect of exercise have been obtained, the mechanisms underlying this phenomenon have not yet been fully clarified. Further studies are warranted to define precise exercise prescriptions in patients at risk of myocardial infarction or undergoing chemotherapy.
Collapse
Affiliation(s)
- Claudia Penna
- National Institute for Cardiovascular Research (INRC), Bologna, Italy.,Department of Clinical and Biological Sciences, University of Turin, Torino, Italy
| | | | - Antonio Crisafulli
- Department of Medical Sciences and Public Health, Sports Physiology Lab., University of Cagliari, Cagliari, Italy
| |
Collapse
|
15
|
Wang X, Fitts RH. Cardiomyocyte slowly activating delayed rectifier potassium channel: regulation by exercise and β-adrenergic signaling. J Appl Physiol (1985) 2020; 128:1177-1185. [DOI: 10.1152/japplphysiol.00802.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Results demonstrate that exercise training (TRN) downregulates ventricular IKs channel current and the channel’s responsiveness to β-agonist factors mediated by TRN-induced decline in channel subunits KCNQ1 and KCNE1 and the A-kinase anchoring protein yotiao. The reduced IKs current helps explain the TRN-induced prolongation of the action potential in basal conditions and, coupled with previously reported upregulation of the KATP channel, results in a more efficient heart that is better able to respond to beat-by-beat changes in metabolism.
Collapse
Affiliation(s)
- Xinrui Wang
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Robert H. Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| |
Collapse
|
16
|
Kaya ST, Bozdogan O, Ozarslan TO, Taskin E, Eksioglu D, Erim F, Firat T, Yasar S. The protection of resveratrol and its combination with glibenclamide, but not berberine on the diabetic hearts against reperfusion-induced arrhythmias: the role of myocardial K ATP channel. Arch Physiol Biochem 2019; 125:114-121. [PMID: 29457517 DOI: 10.1080/13813455.2018.1440409] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
CONTEXT Cardiovascular dysfunctions such as life-threatening arrhythmias are one of the main reasons of mortality and morbidity in diabetic patients Objective: We aimed to investigate the long-term effects of resveratrol, berberine and glibenclamide combinations on the ischemia/reperfusion (I/R) induced arrhythmias in streptozotocin (STZ)-induced diabetic rats and to investigate the role of myocardial KATP channel in the possible anti-arrhythmic actions of the treatments. METHODS Two days after induction of diabetes, diabetic rats were treated with resveratrol [5 mg/kg, intraperitoneally (i.p.)], berberine (10 mg/kg, i.p) and glibenclamide (5 mg/kg, i.p) for 6 weeks. On the 43th day, experimental animals were subjected to 6-min ischemia and 6-min reperfusion in vivo. RESULTS The protein expression of Kir6.2 subunits was downregulated in the diabetic hearts. However, all drug treatments restored the protein expression of Kir6.2 subunits. Resveratrol alone and its combination with glibenclamide decreased the arrhythmia score, the arrhythmic period and the incidence of other types of arrhythmias during the reperfusion period. CONCLUSIONS The combination of resveratrol with glibenclamide may alleviate reperfusion-induced arrhythmias via an underlying mechanism not be only associated with the restoration of the protein expression of Kir6.2 subunits but also associated with the other subunits or ion channels underlying cardiac action potential.
Collapse
Affiliation(s)
- Salih T Kaya
- a Faculty of Arts and Science, Department of Biology , Düzce University , Düzce , Turkey
| | - Omer Bozdogan
- b Faculty of Arts and Science, Department of Biology , Abant İzzet Baysal University , Bolu , Turkey
| | - Talat O Ozarslan
- b Faculty of Arts and Science, Department of Biology , Abant İzzet Baysal University , Bolu , Turkey
| | - Eylem Taskin
- c Department of Physiology, Faculty of Medicine , Niğde Ömer Halisdemir University , Niğde , Turkey
| | - Didem Eksioglu
- b Faculty of Arts and Science, Department of Biology , Abant İzzet Baysal University , Bolu , Turkey
| | - Firdevs Erim
- b Faculty of Arts and Science, Department of Biology , Abant İzzet Baysal University , Bolu , Turkey
| | - Tulin Firat
- d Faculty of Medicine, Department of Histology and Embryology , Abant İzzet Baysal University , Bolu , Turkey
| | - Selcuk Yasar
- b Faculty of Arts and Science, Department of Biology , Abant İzzet Baysal University , Bolu , Turkey
| |
Collapse
|
17
|
Subbotina E, Yang HQ, Gando I, Williams N, Sampson BA, Tang Y, Coetzee WA. Functional characterization of ABCC9 variants identified in sudden unexpected natural death. Forensic Sci Int 2019; 298:80-87. [PMID: 30878466 DOI: 10.1016/j.forsciint.2019.02.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Genetic variation in ion channel genes ('channelopathies') are often associated with inherited arrhythmias and sudden death. Genetic testing ('molecular autopsies') of channelopathy genes can be used to assist in determining the likely causes of sudden unexpected death. However, different in silico approaches can yield conflicting pathogenicity predictions and assessing their impact on ion channel function can assist in this regard. METHODS AND RESULTS We performed genetic testing of cases of sudden expected death in the New York City metropolitan area and found four rare or novel variants in ABCC9, which codes for the regulatory SUR2 subunit of KATP channels. All were missense variants, causing amino acid changes in the protein. Three of the variants (A355S, M941V, and K1379Q) were in cases of infants less than six-months old and one (H1305Y) was in an adult. The predicted pathogenicities of the variants were conflicting. We have introduced these variants into a human SUR2A cDNA, which we coexpressed with the Kir6.2 pore-forming subunit in HEK-293 cells and subjected to patch clamp and biochemical assays. Each of the four variants led to gain-of-function phenotypes. The A355S and M941V variants increased in the overall patch current. The sensitivity of the KATP channels to inhibitory 'cytosolic' ATP was repressed for the M941V, H1305Y and K1379Q variants. None of the variants had any effect on the unitary KATP channel current or the surface expression of KATP channels, as determined with biotinylation assays, suggesting that all of the variants led to an enhanced open state. CONCLUSIONS All four variants caused a gain-of-function phenotype. Given the expression of SUR2-containing KATP channels in the heart and specialized cardiac conduction, vascular smooth muscle and respiratory neurons, it is conceivable that electrical silencing of these cells may contribute to the vulnerability element, which is a component of the triple risk model of sudden explained death in infants. The gain-of-function phenotype of these ABCC9 variants should be considered when assessing their potential pathogenicity.
Collapse
Affiliation(s)
| | - Hua-Qian Yang
- Departments of Pediatrics, NYU School of Medicine, New York, NY 10016 USA
| | - Ivan Gando
- Departments of Pediatrics, NYU School of Medicine, New York, NY 10016 USA
| | - Nori Williams
- Molecular Genetics Laboratory, Office of Chief Medical Examiner, New York, NY USA
| | - Barbara A Sampson
- Molecular Genetics Laboratory, Office of Chief Medical Examiner, New York, NY USA
| | - Yingying Tang
- Molecular Genetics Laboratory, Office of Chief Medical Examiner, New York, NY USA
| | - William A Coetzee
- Departments of Pediatrics, NYU School of Medicine, New York, NY 10016 USA; Departments of Physiology & Neuroscience NYU School of Medicine, New York, NY 10016 USA; Departments of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016 USA.
| |
Collapse
|
18
|
Chowdhury MA, Sholl HK, Sharrett MS, Haller ST, Cooper CC, Gupta R, Liu LC. Exercise and Cardioprotection: A Natural Defense Against Lethal Myocardial Ischemia-Reperfusion Injury and Potential Guide to Cardiovascular Prophylaxis. J Cardiovasc Pharmacol Ther 2019; 24:18-30. [PMID: 30041547 PMCID: PMC7236859 DOI: 10.1177/1074248418788575] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Similar to ischemic preconditioning, high-intensity exercise has been shown to decrease infarct size following myocardial infarction. In this article, we review the literature on beneficial effects of exercise, exercise requirements for cardioprotection, common methods utilized in laboratories to study this phenomenon, and discuss possible mechanisms for exercise-mediated cardioprotection.
Collapse
Affiliation(s)
- Mohammed Andaleeb Chowdhury
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
- * Mohammed Andaleeb Chowdhury, Haden K. Sholl, and Megan S. Sharrett contributed equally to this work
| | - Haden K Sholl
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
- * Mohammed Andaleeb Chowdhury, Haden K. Sholl, and Megan S. Sharrett contributed equally to this work
| | - Megan S Sharrett
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Steven T Haller
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Christopher C Cooper
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Rajesh Gupta
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| | - Lijun C Liu
- 1 Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA
| |
Collapse
|
19
|
Bernardo BC, Ooi JYY, Weeks KL, Patterson NL, McMullen JR. Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging Concepts. Physiol Rev 2018; 98:419-475. [PMID: 29351515 DOI: 10.1152/physrev.00043.2016] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The benefits of exercise on the heart are well recognized, and clinical studies have demonstrated that exercise is an intervention that can improve cardiac function in heart failure patients. This has led to significant research into understanding the key mechanisms responsible for exercise-induced cardiac protection. Here, we summarize molecular mechanisms that regulate exercise-induced cardiac myocyte growth and proliferation. We discuss in detail the effects of exercise on other cardiac cells, organelles, and systems that have received less or little attention and require further investigation. This includes cardiac excitation and contraction, mitochondrial adaptations, cellular stress responses to promote survival (heat shock response, ubiquitin-proteasome system, autophagy-lysosomal system, endoplasmic reticulum unfolded protein response, DNA damage response), extracellular matrix, inflammatory response, and organ-to-organ crosstalk. We summarize therapeutic strategies targeting known regulators of exercise-induced protection and the challenges translating findings from bench to bedside. We conclude that technological advancements that allow for in-depth profiling of the genome, transcriptome, proteome and metabolome, combined with animal and human studies, provide new opportunities for comprehensively defining the signaling and regulatory aspects of cell/organelle functions that underpin the protective properties of exercise. This is likely to lead to the identification of novel biomarkers and therapeutic targets for heart disease.
Collapse
Affiliation(s)
- Bianca C Bernardo
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Jenny Y Y Ooi
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Kate L Weeks
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Natalie L Patterson
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| |
Collapse
|
20
|
Wang X, Fitts RH. Effects of regular exercise on ventricular myocyte biomechanics and KATP channel function. Am J Physiol Heart Circ Physiol 2018; 315:H885-H896. [DOI: 10.1152/ajpheart.00130.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Exercise training is known to protect the heart from ischemia and improve function during exercise by reducing cardiomyocyte action potential duration (APD) and increasing contractility. The cellular mechanisms involve β-adrenergic regulation and the ATP-sensitive K+ (KATP) channel, but how each alters function of the left ventricle and sex specificity is unknown. To address this, female and male Sprague-Dawley rats were randomly assigned to wheel-running (TRN) or sedentary (SED) groups. After 6–8 wk of training, myocytes were isolated from the left ventricle and field stimulated at 1, 2, and 5 Hz. TRN significantly increased cardiomyocyte contractility, the kinetics of the Ca2+ transient, and responsiveness to the adrenergic receptor agonist isoproterenol (ISO), as reflected by an increased sarcomere shortening. Importantly, we demonstrated a TRN-induced upregulation of KATP channels, which was reflected by elevated content, current density, and the channel’s contribution to APD shortening at high activation rates and in the presence of the activator pinacidil. TRN induced increase in KATP current occurred throughout the left ventricle, but channel subunit content showed regional specificity with increases in Kir6.2 in the apex and SUR2A in base regions. In summary, TRN elevated cardiomyocyte cross-bridge kinetics, Ca2+ sensitivity, and the responsiveness of contractile function to β-adrenergic receptor stimulation in both sexes. Importantly, upregulation of the KATP channel accelerates repolarization and shortens APD during stress and exercise. These adaptations have clinical importance, as increased contractility and reduced APD would help protect cardiac output and reduce intracellular Ca2+ overload during stresses such as regional ischemia. NEW & NOTEWORTHY Our results demonstrate that regular exercise significantly increased ventricular myocyte shortening and relaxation velocity and the rate of rise in intracellular Ca2+ transient and enhanced the response of biomechanics and Ca2+ reuptake to β-adrenergic stimulation. Importantly, exercise training upregulated the cardiomyocyte sarcolemma ATP-sensitive K+ channel across the left ventricle in both sexes, as reflected by elevated channel subunit content, current density, and the channel’s contribution to reduced action potential duration at high activation rates.
Collapse
Affiliation(s)
- Xinrui Wang
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Robert H. Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| |
Collapse
|
21
|
Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
22
|
Zhang Q, Li C, Zhang T, Ge Y, Han X, Sun S, Ding J, Lu M, Hu G. Deletion of Kir6.2/SUR1 potassium channels rescues diminishing of DA neurons via decreasing iron accumulation in PD. Mol Cell Neurosci 2018; 92:164-176. [PMID: 30171894 DOI: 10.1016/j.mcn.2018.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/16/2018] [Accepted: 08/25/2018] [Indexed: 11/25/2022] Open
Abstract
ATP-sensitive potassium (K-ATP) channels express in the central nervous system extensively which coupling cell metabolism and cellular electrical activity. K-ATP channels in mature substantia nigra (SN) dopaminergic (DA) neurons are composed of inwardly rectifying potassium channel (Kir) subunit 6.2 and sulfonylurea receptor 1 (SUR1). Our previous study revealed that regulating K-ATP channel exerts the protective effect on DA neurons in a mouse model of Parkinson's disease (PD). However, the detailed mechanism underlying the role of Kir6.2/K-ATP remains unclear. In the present study, we found the deletion of Kir6.2 dramatically alleviated PD-like motor dysfunction of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD model. We further found that Kir6.2 knockout selectively restored the reduction of both DA neuronal number and dopamine transmitter level in the nigrostriatal of MPTP-treated PD mice. To gain some understanding on the molecular basis of this effect, we focused on the regulation of Kir6.2 deletion on iron metabolism which is tightly associated with DA neuron damage. We found that Kir6.2 knockout suppressed the excessive iron accumulation in MPTP-treated mouse midbrain and inhibited the upregulation of ferritin light chain (FTL), which is a main intracellular iron storage protein. We probed further and found out that the deletion of Kir6.2 inhibited the excessive production of FTL via IRP-IRE regulatory system, and thereby protecting SN DA neurons against MPTP challenge. Our findings suggest that Kir6.2 plays a crucial role in the pathogenesis of PD and regulating Kir6.2/K-ATP channel may be a promising strategy for PD treatment.
Collapse
Affiliation(s)
- Qian Zhang
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Chengwu Li
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Ting Zhang
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Yaping Ge
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Xiaojuan Han
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Sifan Sun
- First Clinic Medical School, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China
| | - Jianhua Ding
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu 211166, China
| | - Ming Lu
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu 211166, China.
| | - Gang Hu
- Department of Pharmacology, School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Nanjing, Jiangsu 210023, China; Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu 211166, China.
| |
Collapse
|
23
|
Lu J, Pan SS, Wang QT, Yuan Y. Alterations of Cardiac K ATP Channels and Autophagy Contribute in the Late Cardioprotective Phase of Exercise Preconditioning. Int Heart J 2018; 59:1106-1115. [PMID: 30101842 DOI: 10.1536/ihj.17-003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The cardiac effects of exercise preconditioning (EP) are well established; however, the mechanisms involving cardiac ATP-sensitive potassium channel (KATP channel) subunits and autophagy are yet to be fully established. The present work aims to investigate the alterations of cardiac KATP channel subunits Kir6.2, SUR2A, and autophagy-related LC3 during the late cardioprotective phase of EP against exhaustive exercise-induced myocardial injury. Rats run on treadmill for four running time intervals, each with 10 minutes running and rest. Exhaustive exercise was performed 24 h after EP. Cardiac biomarkers, cTnI and NT-proBNP, along with the histological stain, were served as indicators of myocardial injury. Cardiac KATP channel subunits Kir6.2 and SUR2A were analyzed in this study, and autophagy was evaluated by LC3. The results revealed that EP reduced the exhaustive exercise-induced high level of serum cTnI and myocardial ischemia/hypoxia; however, it did not reveal any changes in the serum NT-proBNP level or cardiac BNP. Cardiac SUR2A mRNA significantly upregulated during the exhaustive exercise. The high levels of Kir6.2, SUR2A, LC3IIpuncta and LC3II turnover observed after exhaustive exercise were significantly mitigated by EP in the late phase. These results suggest that EP alleviates myocardial injury induced by exhaustive exercise through the downregulation of cardiac KATP channels and autophagy.
Collapse
Affiliation(s)
- Jiao Lu
- School of Kinesiology, Shanghai University of Sport
| | | | | | - Yang Yuan
- School of Kinesiology, Shanghai University of Sport
| |
Collapse
|
24
|
Wang X, Fitts RH. Ventricular action potential adaptation to regular exercise: role of β-adrenergic and KATP channel function. J Appl Physiol (1985) 2017; 123:285-296. [DOI: 10.1152/japplphysiol.00197.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/21/2017] [Accepted: 05/15/2017] [Indexed: 01/06/2023] Open
Abstract
Regular exercise training is known to affect the action potential duration (APD) and improve heart function, but involvement of β-adrenergic receptor (β-AR) subtypes and/or the ATP-sensitive K+ (KATP) channel is unknown. To address this, female and male Sprague-Dawley rats were randomly assigned to voluntary wheel-running or control groups; they were anesthetized after 6–8 wk of training, and myocytes were isolated. Exercise training significantly increased APD of apex and base myocytes at 1 Hz and decreased APD at 10 Hz. Ca2+ transient durations reflected the changes in APD, while Ca2+ transient amplitudes were unaffected by wheel running. The nonselective β-AR agonist isoproterenol shortened the myocyte APD, an effect reduced by wheel running. The isoproterenol-induced shortening of APD was largely reversed by the selective β1-AR blocker atenolol, but not the β2-AR blocker ICI 118,551, providing evidence that wheel running reduced the sensitivity of the β1-AR. At 10 Hz, the KATP channel inhibitor glibenclamide prolonged the myocyte APD more in exercise-trained than control rats, implicating a role for this channel in the exercise-induced APD shortening at 10 Hz. A novel finding of this work was the dual importance of altered β1-AR responsiveness and KATP channel function in the training-induced regulation of APD. Of physiological importance to the beating heart, the reduced response to adrenergic agonists would enhance cardiac contractility at resting rates, where sympathetic drive is low, by prolonging APD and Ca2+ influx; during exercise, an increase in KATP channel activity would shorten APD and, thus, protect the heart against Ca2+ overload or inadequate filling. NEW & NOTEWORTHY Our data demonstrated that regular exercise prolonged the action potential and Ca2+ transient durations in myocytes isolated from apex and base regions at 1-Hz and shortened both at 10-Hz stimulation. Novel findings were that wheel running shifted the β-adrenergic receptor agonist dose-response curve rightward compared with controls by reducing β1-adrenergic receptor responsiveness and that, at the high activation rate, myocytes from trained animals showed higher KATP channel function.
Collapse
Affiliation(s)
- Xinrui Wang
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Robert H. Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| |
Collapse
|
25
|
Fatehi M, Carter CC, Youssef N, Light PE. The mechano-sensitivity of cardiac ATP-sensitive potassium channels is mediated by intrinsic MgATPase activity. J Mol Cell Cardiol 2017; 108:34-41. [PMID: 28483598 DOI: 10.1016/j.yjmcc.2017.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 10/19/2022]
Abstract
Cardiac ATP-sensitive K+ (KATP) channel activity plays an important cardio-protective role in regulating excitability in response to metabolic stress. Evidence suggests that these channels are also mechano-sensitive and therefore may couple KATP channel activity to increased cardiac workloads. However, the molecular mechanism that couples membrane stretch to channel activity is not currently known. We hypothesized that membrane stretch may alter the intrinsic MgATPase activity of the cardiac KATP channel resulting in increased channel activation. The inside-out patch-clamp technique was used to record single-channel and macroscopic recombinant KATP channel activity in response to membrane stretch elicited by negative pipette pressure. We found that stretch activation requires the presence of the SUR subunit and that inhibition of MgATPase activity with either the non-hydrolysable ATP analog AMP-PNP or the ATPase inhibitor BeFx significantly reduced the stimulatory effect of stretch. We employed a point mutagenic approach to determine that a single residue (K1337) in the hairpin loop proximal to the major MgATPase catalytic site in the SUR2A subunit is responsible for the difference in mechano-sensitivity between SUR2A and SUR1 containing KATP channels. Moreover, using a double cysteine mutant substitution in the hairpin loop region revealed the importance of a key residue-residue interaction in this region that transduces membrane mechanical forces into KATP channel stimulation via increases in channel MgATPase activity. With respect to KATP channel pharmacology, glibenclamide, but not glicalizide or repaglinide, was able to completely inhibit KATP channel mechano-sensitivity. In summary, our results provide a highly plausible molecular mechanism by which mechanical membrane forces are rapidly converted in changes in KATP channel activity that have implications for our understanding of cardiac KATP channels in physiological or pathophysiological settings that involve increased workload.
Collapse
Affiliation(s)
- Mohammad Fatehi
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Christian C Carter
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Nermeen Youssef
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Peter E Light
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
| |
Collapse
|
26
|
Garrott K, Kuzmiak-Glancy S, Wengrowski A, Zhang H, Rogers J, Kay MW. K ATP channel inhibition blunts electromechanical decline during hypoxia in left ventricular working rabbit hearts. J Physiol 2017; 595:3799-3813. [PMID: 28177123 DOI: 10.1113/jp273873] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 02/01/2017] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS Heart function is critically dependent upon the balance of energy production and utilization. Sarcolemmal ATP-sensitive potassium channels (KATP channels) in cardiac myocytes adjust contractile function to compensate for the level of available energy. Understanding the activation of KATP channels in working myocardium during high-stress situations is crucial to the treatment of cardiovascular disease, especially ischaemic heart disease. Using a new optical mapping approach, we measured action potentials from the surface of excised contracting rabbit hearts to assess when sarcolemmal KATP channels were activated during physiologically relevant workloads and during gradual reductions in myocardial oxygenation. We demonstrate that left ventricular pressure is closely linked to KATP channel activation and that KATP channel inhibition with a low concentration of tolbutamide prevents electromechanical decline when oxygen availability is reduced. As a result, KATP channel inhibition probably exacerbates a mismatch between energy demand and energy production when myocardial oxygenation is low. ABSTRACT Sarcolemmal ATP-sensitive potassium channel (KATP channel) activation in isolated cells is generally understood, although the relationship between myocardial oxygenation and KATP activation in excised working rabbit hearts remains unknown. We optically mapped action potentials (APs) in excised rabbit hearts to test the hypothesis that hypoxic changes would be more severe in left ventricular (LV) working hearts (LWHs) than Langendorff (LANG) perfused hearts. We further hypothesized that KATP inhibition would prevent those changes. Optical APs were mapped when measuring LV developed pressure (LVDP), coronary flow rate and oxygen consumption in LANG and LWHs. Hearts were paced to increase workload and perfusate was deoxygenated to study the effects of myocardial hypoxia. A subset of hearts was perfused with 1 μm tolbutamide (TOLB) to identify the level of AP duration (APD) shortening attributed to KATP channel activation. During sinus rhythm, APD was shorter in LWHs compared to LANG hearts. APD in both LWHs and LANG hearts dropped steadily during deoxygenation. With TOLB, APDs in LWHs were longer at all workloads and APD reductions during deoxygenation were blunted in both LWHs and LANG hearts. At 50% perfusate oxygenation, APD and LVDP were significantly higher in LWHs perfused with TOLB (199 ± 16 ms; 92 ± 5.3 mmHg) than in LWHs without TOLB (109 ± 14 ms, P = 0.005; 65 ± 6.5 mmHg, P = 0.01). Our results indicate that KATP channels are activated to a greater extent in perfused hearts when the LV performs pressure-volume work. The results of the present study demonstrate the critical role of KATP channels in modulating myocardial function over a wide range of physiological conditions.
Collapse
Affiliation(s)
- Kara Garrott
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Sarah Kuzmiak-Glancy
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Anastasia Wengrowski
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Hanyu Zhang
- Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jack Rogers
- Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| |
Collapse
|
27
|
Borges JP, da Silva Verdoorn K. Cardiac Ischemia/Reperfusion Injury: The Beneficial Effects of Exercise. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:155-179. [PMID: 29022263 DOI: 10.1007/978-981-10-4307-9_10] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cardiac ischemia reperfusion injury (IRI) occurs when the myocardium is revascularized after an episode of limited or absent blood supply. Many changes, including free radical production, calcium overload, protease activation, altered membrane lipids and leukocyte activation, contribute to IRI-induced myocardium damage. Aerobic exercise is the only countermeasure against IRI that can be sustained on a regular basis in clinical practice. Interestingly, both short-term (3-5 days) and long-term (several weeks) exercise increase myocardial tolerance, reduce infarct size area and arrhythmias induced by IRI. Exercise protects the heart against IRI in a biphasic manner. The early phase of cardioprotection occurs between 30 min and 3 h following an acute exercise bout, whilst the late phase is achieved within 24 h after the exercise bout and persists for several days. As for the exercise intensity, although controversial data exists, it is feasible that the amount of cardioprotection is proportional to exercise intensity and only achieved above a critical threshold. It is known that aerobic exercise produces a cardioprotective phenotype, however the mechanisms responsible for this phenomenon remain unclear. Apparently, aerobic exercise-induced preconditioning is dependent on several factors that work together to protect the heart. Altered nitric oxide (NO) signaling, increased levels of heat shock proteins (HSPs), enhanced function of ATP-sensitive potassium channels, increased activation of opioids system, and enhanced antioxidant capacity may contribute to exercise-induced cardioprotection. Much has been discovered from animal models involving exercise-induced cardioprotection against cardiac IRI, however translating these findings to clinical practice still represents the major challenge in this field.
Collapse
Affiliation(s)
- Juliana Pereira Borges
- Institute of Physical Education and Sports, State University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
| | | |
Collapse
|
28
|
Krzesiak A, Delpech N, Sebille S, Cognard C, Chatelier A. Structural, Contractile and Electrophysiological Adaptations of Cardiomyocytes to Chronic Exercise. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:75-90. [PMID: 29022258 DOI: 10.1007/978-981-10-4307-9_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cardiac beneficial effects of chronic exercise is well admitted. These effects mainly studied at the organ and organism integrated levels find their origin in cardiomyocyte adaptation. This chapter try to highlight the main trends of the data related to the different parameters subject to such adaptations. This is addressed through cardiomyocytes size and structure, calcium and contractile properties, and finally electrophysiological alterations induced by training as they transpire from the literature. Despite the clarifications needed to decipher healthy cardiomyocyte remodeling, this overview clearly show that cardiac cell plasticity ensure the cardiac adaptation to exercise training and offers an interesting mean of action to counteract physiological disturbances induced by cardiac pathologies.
Collapse
Affiliation(s)
- A Krzesiak
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.,Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - N Delpech
- Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - S Sebille
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - C Cognard
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.
| |
Collapse
|
29
|
Yang HQ, Subbotina E, Ramasamy R, Coetzee WA. Cardiovascular K ATP channels and advanced aging. PATHOBIOLOGY OF AGING & AGE RELATED DISEASES 2016; 6:32517. [PMID: 27733235 PMCID: PMC5061878 DOI: 10.3402/pba.v6.32517] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/12/2016] [Accepted: 09/14/2016] [Indexed: 12/20/2022]
Abstract
With advanced aging, there is a decline in innate cardiovascular function. This decline is not general in nature. Instead, specific changes occur that impact the basic cardiovascular function, which include alterations in biochemical pathways and ion channel function. This review focuses on a particular ion channel that couple the latter two processes, namely the KATP channel, which opening is promoted by alterations in intracellular energy metabolism. We show that the intrinsic properties of the KATP channel changes with advanced aging and argue that the channel can be further modulated by biochemical changes. The importance is widespread, given the ubiquitous nature of the KATP channel in the cardiovascular system where it can regulate processes as diverse as cardiac function, blood flow and protection mechanisms against superimposed stress, such as cardiac ischemia. We highlight questions that remain to be answered before the KATP channel can be considered as a viable target for therapeutic intervention.
Collapse
Affiliation(s)
- Hua-Qian Yang
- Department of Pediatrics, NYU School of Medicine, New York, NY, USA
| | | | - Ravichandran Ramasamy
- Department of Medicine, NYU School of Medicine, New York, NY, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY, USA
| | - William A Coetzee
- Department of Pediatrics, NYU School of Medicine, New York, NY, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY, USA.,Department of Physiology & Neuroscience, NYU School of Medicine, New York, NY, USA;
| |
Collapse
|
30
|
Gao Z, Sierra A, Zhu Z, Koganti SRK, Subbotina E, Maheshwari A, Anderson ME, Zingman LV, Hodgson-Zingman DM. Loss of ATP-Sensitive Potassium Channel Surface Expression in Heart Failure Underlies Dysregulation of Action Potential Duration and Myocardial Vulnerability to Injury. PLoS One 2016; 11:e0151337. [PMID: 26964104 PMCID: PMC4786327 DOI: 10.1371/journal.pone.0151337] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/26/2016] [Indexed: 11/18/2022] Open
Abstract
The search for new approaches to treatment and prevention of heart failure is a major challenge in medicine. The adenosine triphosphate-sensitive potassium (KATP) channel has been long associated with the ability to preserve myocardial function and viability under stress. High surface expression of membrane KATP channels ensures a rapid energy-sparing reduction in action potential duration (APD) in response to metabolic challenges, while cellular signaling that reduces surface KATP channel expression blunts APD shortening, thus sacrificing energetic efficiency in exchange for greater cellular calcium entry and increased contractile force. In healthy hearts, calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylates the Kir6.2 KATP channel subunit initiating a cascade responsible for KATP channel endocytosis. Here, activation of CaMKII in a transaortic banding (TAB) model of heart failure is coupled with a 35–40% reduction in surface expression of KATP channels compared to hearts from sham-operated mice. Linkage between KATP channel expression and CaMKII is verified in isolated cardiomyocytes in which activation of CaMKII results in downregulation of KATP channel current. Accordingly, shortening of monophasic APD is slowed in response to hypoxia or heart rate acceleration in failing compared to non-failing hearts, a phenomenon previously shown to result in significant increases in oxygen consumption. Even in the absence of coronary artery disease, failing myocardium can be further injured by ischemia due to a mismatch between metabolic supply and demand. Ischemia-reperfusion injury, following ischemic preconditioning, is diminished in hearts with CaMKII inhibition compared to wild-type hearts and this advantage is largely eliminated when myocardial KATP channel expression is absent, supporting that the myocardial protective benefit of CaMKII inhibition in heart failure may be substantially mediated by KATP channels. Recognition of CaMKII-dependent downregulation of KATP channel expression as a mechanism for vulnerability to injury in failing hearts points to strategies targeting this interaction for potential preventives or treatments.
Collapse
Affiliation(s)
- Zhan Gao
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ana Sierra
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Zhiyong Zhu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Siva Rama Krishna Koganti
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ekaterina Subbotina
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ankit Maheshwari
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Mark E. Anderson
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
| | - Leonid V. Zingman
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States of America
- Veterans Affairs Medical Center, Iowa City, Iowa, United States of America
| | - Denice M. Hodgson-Zingman
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
| |
Collapse
|
31
|
Abstract
KATP channels are integral to the functions of many cells and tissues. The use of electrophysiological methods has allowed for a detailed characterization of KATP channels in terms of their biophysical properties, nucleotide sensitivities, and modification by pharmacological compounds. However, even though they were first described almost 25 years ago (Noma 1983, Trube and Hescheler 1984), the physiological and pathophysiological roles of these channels, and their regulation by complex biological systems, are only now emerging for many tissues. Even in tissues where their roles have been best defined, there are still many unanswered questions. This review aims to summarize the properties, molecular composition, and pharmacology of KATP channels in various cardiovascular components (atria, specialized conduction system, ventricles, smooth muscle, endothelium, and mitochondria). We will summarize the lessons learned from available genetic mouse models and address the known roles of KATP channels in cardiovascular pathologies and how genetic variation in KATP channel genes contribute to human disease.
Collapse
Affiliation(s)
- Monique N Foster
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - William A Coetzee
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| |
Collapse
|
32
|
LIANG WEIJIE, CHEN JINGFU, MO LIQIU, KE XIAO, ZHANG WENZHU, ZHENG DONGDAN, PAN WANYING, WU SHAOYUN, FENG JIANQIANG, SONG MINGCAI, LIAO XINXUE. ATP-sensitive K+ channels contribute to the protective effects of exogenous hydrogen sulfide against high glucose-induced injury in H9c2 cardiac cells. Int J Mol Med 2016; 37:763-72. [DOI: 10.3892/ijmm.2016.2467] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 01/15/2016] [Indexed: 11/06/2022] Open
|
33
|
KRALJEVIC JASENKA, HØYDAL MORTENANDRE, LJUBKOVIC MARKO, MOREIRA JOSEBIANCONASCIMENTO, JØRGENSEN KARI, NESS HENNINGOFSTAD, BÆKKERUD FREDRIKHJULSTAD, DUJIC ZELJKO, WISLØFF ULRIK, MARINOVIC JASNA. Role of KATP Channels in Beneficial Effects of Exercise in Ischemic Heart Failure. Med Sci Sports Exerc 2015; 47:2504-12. [DOI: 10.1249/mss.0000000000000714] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
34
|
Bayat G, Javan M, Safari F, Khalili A, Shokri S, Goudarzvand M, Salimi M, Hajizadeh S. Nandrolone decanoate negatively reverses the beneficial effects of exercise on cardiac muscle via sarcolemmal, but not mitochondrial K(ATP) channel. Can J Physiol Pharmacol 2015; 94:324-31. [PMID: 26909616 DOI: 10.1139/cjpp-2015-0040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
ATP-sensitive potassium channels are supposed to have a substantial role in improvement of cardiac performance. This study was performed to evaluate whether nandrolone decanoate (ND) and (or) exercise training could affect the expression of cardiac K(ATP) channel subunits. Thirty-five male albino Wistar rats were randomly divided into 5 groups, including sedentary control (SC), sedentary vehicle (SV), sedentary ND (SND), exercise control (EC), and exercise and ND (E+ND). Exercise training was performed on a treadmill 5 times per week. ND was injected (10 mg/kg/week, i.m.) to the rats in the SND and E+ND groups. Following cardiac isolation, the expression of both sarcolemmal and mitochondrial subunits of K(ATP) channel was measured using Western blot method. The expression of sarcolemmal, but not mitochondrial, subunits of K(ATP) channel (Kir6.2 and SUR2) of EC group was significantly higher compared with SC group while ND administration (SND group) did not show any change in their expression. In the E+ND group, ND administration led to decrease of the over-expression of sarcolemmal Kir6.2 and SUR2 which was previously induced by exercise. There was no significant association between the mitochondrial expression of either Kir6.2 or SUR2 proteins and administration of ND or exercise. Supra-physiological dosage of ND negatively reverses the effects of exercise on the cardiac muscle expression of sarcolemmal, but not mitochondrial, K(ATP) channel subunits.
Collapse
Affiliation(s)
- Gholamreza Bayat
- a Department of Physiology and Pharmacology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Mohammad Javan
- b Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Fatemeh Safari
- c Deptartment of Physiology, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Azadeh Khalili
- d Department of Pharmacology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Saeed Shokri
- e Department of Anatomy, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Mahdi Goudarzvand
- a Department of Physiology and Pharmacology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Mehdi Salimi
- b Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Sohrab Hajizadeh
- b Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| |
Collapse
|
35
|
Inhibition of MCU forces extramitochondrial adaptations governing physiological and pathological stress responses in heart. Proc Natl Acad Sci U S A 2015; 112:9129-34. [PMID: 26153425 DOI: 10.1073/pnas.1504705112] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Myocardial mitochondrial Ca(2+) entry enables physiological stress responses but in excess promotes injury and death. However, tissue-specific in vivo systems for testing the role of mitochondrial Ca(2+) are lacking. We developed a mouse model with myocardial delimited transgenic expression of a dominant negative (DN) form of the mitochondrial Ca(2+) uniporter (MCU). DN-MCU mice lack MCU-mediated mitochondrial Ca(2+) entry in myocardium, but, surprisingly, isolated perfused hearts exhibited higher O2 consumption rates (OCR) and impaired pacing induced mechanical performance compared with wild-type (WT) littermate controls. In contrast, OCR in DN-MCU-permeabilized myocardial fibers or isolated mitochondria in low Ca(2+) were not increased compared with WT, suggesting that DN-MCU expression increased OCR by enhanced energetic demands related to extramitochondrial Ca(2+) homeostasis. Consistent with this, we found that DN-MCU ventricular cardiomyocytes exhibited elevated cytoplasmic [Ca(2+)] that was partially reversed by ATP dialysis, suggesting that metabolic defects arising from loss of MCU function impaired physiological intracellular Ca(2+) homeostasis. Mitochondrial Ca(2+) overload is thought to dissipate the inner mitochondrial membrane potential (ΔΨm) and enhance formation of reactive oxygen species (ROS) as a consequence of ischemia-reperfusion injury. Our data show that DN-MCU hearts had preserved ΔΨm and reduced ROS during ischemia reperfusion but were not protected from myocardial death compared with WT. Taken together, our findings show that chronic myocardial MCU inhibition leads to previously unanticipated compensatory changes that affect cytoplasmic Ca(2+) homeostasis, reprogram transcription, increase OCR, reduce performance, and prevent anticipated therapeutic responses to ischemia-reperfusion injury.
Collapse
|
36
|
Koganti SRK, Zhu Z, Subbotina E, Gao Z, Sierra A, Proenza M, Yang L, Alekseev A, Hodgson-Zingman D, Zingman L. Disruption of KATP channel expression in skeletal muscle by targeted oligonucleotide delivery promotes activity-linked thermogenesis. Mol Ther 2015; 23:707-16. [PMID: 25648265 DOI: 10.1038/mt.2015.21] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 01/19/2015] [Indexed: 12/18/2022] Open
Abstract
Despite the medical, social, and economic impact of obesity, only a few therapeutic options, focused largely on reducing caloric intake, are currently available and these have limited success rates. A major impediment is that any challenge by caloric restriction is counterbalanced by activation of systems that conserve energy to prevent body weight loss. Therefore, targeting energy-conserving mechanisms to promote energy expenditure is an attractive strategy for obesity treatment. Here, in order to suppress muscle energy efficiency, we target sarcolemmal ATP-sensitive potassium (KATP) channels which have previously been shown to be important in maintaining muscle energy economy. Specifically, we employ intramuscular injections of cell-penetrating vivo-morpholinos to prevent translation of the channel pore-forming subunit. This intervention results in significant reduction of KATP channel expression and function in treated areas, without affecting the channel expression in nontargeted tissues. Furthermore, suppression of KATP channel function in a group of hind limb muscles causes a substantial increase in activity-related energy consumption, with little effect on exercise tolerance. These findings establish a proof-of-principle that selective skeletal muscle targeting of sarcolemmal KATP channel function is possible and that this intervention can alter overall bodily energetics without a disabling impact on muscle mechanical function.
Collapse
Affiliation(s)
- Siva Rama Krishna Koganti
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Zhiyong Zhu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Ekaterina Subbotina
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Zhan Gao
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Ana Sierra
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Manuel Proenza
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Liping Yang
- Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Alexey Alekseev
- Department of Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
| | - Denice Hodgson-Zingman
- 1] Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA [2] Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA [3] François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Leonid Zingman
- 1] Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA [2] Veterans Affairs Medical Center, Iowa City, Iowa, USA [3] Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA [4] François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, USA
| |
Collapse
|
37
|
Gong L, Gao F, Li J, Li J, Yu X, Ma X, Zheng W, Cui S, Liu K, Zhang M, Kunze W, Liu CY. Oxytocin-induced membrane hyperpolarization in pain-sensitive dorsal root ganglia neurons mediated by Ca(2+)/nNOS/NO/KATP pathway. Neuroscience 2015; 289:417-28. [PMID: 25617653 DOI: 10.1016/j.neuroscience.2014.12.058] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/11/2014] [Accepted: 12/16/2014] [Indexed: 12/27/2022]
Abstract
Oxytocin (OT) plays an important role in pain modulation and antinociception in the central nervous system. However, little is known about its peripheral effects. This study was conducted to investigate the effect of OT on the electrical properties of neurons in the dorsal root ganglia (DRG) and the underlying mechanisms. DRG neurons from adult rats were acutely dissociated and cultured. Intracellular Ca(2+) was determined by fluorescent microscopy using an indicator dye. The electrical properties of DRG neurons were tested by patch-clamp recording. The oxytocin receptor (OTR) and neuronal nitric oxide synthase (nNOS) on DRG neurons were assessed with immunofluorescence assays. OTR co-localized with nNOS in most of Isolectin B4 (IB4)-binding cultured DRG neurons in rats. OT decreased the excitability, increased the outward current, and evoked the membrane hyperpolarization in cultured DRG neurons. Sodium nitroprusside (SNP), the donor of nitric oxide (NO), exerted similar effects as OT on the membrane potential of cultured DRG neurons. OT increased the production of NO in DRGs and cultured DRG neurons. Pre-treatment of the OTR antagonist atosiban or the selective nNOS inhibitor N-Propyl-l-arginine (NPLA) significantly attenuated the hyperpolarization effect evoked by OT. OT produced a concentration-dependent increase in intracellular Ca(2+) in DRG neurons that responds to capsaicin, which can be attenuated by atosiban, but not by NPLA. OT-evoked membrane hyperpolarization and increase of outward current were distinctly attenuated by glibenclamide, a blocker of ATP-sensitive K(+) (KATP) channel. OT might be an endogenous antinociceptive agent and the peripheral antinociceptive effects of OT are mediated by activation of the Ca(2+)/nNOS/NO/KATP pathway in DRG neurons.
Collapse
Affiliation(s)
- L Gong
- Department of Physiology, Shandong University School of Medicine, China
| | - F Gao
- Department of Physiology, Shandong University School of Medicine, China
| | - J Li
- Department of Physiology, Shandong University School of Medicine, China
| | - J Li
- Department of Physiology, Shandong University School of Medicine, China
| | - X Yu
- Department of Physiology, Shandong University School of Medicine, China
| | - X Ma
- Department of Physiology, Shandong University School of Medicine, China
| | - W Zheng
- Department of Physiology, Shandong University School of Medicine, China
| | - S Cui
- Department of Physiology, Shandong University School of Medicine, China
| | - K Liu
- Department of Physiology, Shandong University School of Medicine, China
| | - M Zhang
- Department of Biology, McMaster University, Canada
| | - W Kunze
- The McMaster Brain-Body Institutes, St Joseph's Healthcare, Hamilton, Ontario, Canada
| | - C Y Liu
- Department of Physiology, Shandong University School of Medicine, China; Provincial Key Lab of Mental Disorder, Shandong University School of Medicine, China.
| |
Collapse
|
38
|
Powers SK, Smuder AJ, Kavazis AN, Quindry JC. Mechanisms of exercise-induced cardioprotection. Physiology (Bethesda) 2014; 29:27-38. [PMID: 24382869 DOI: 10.1152/physiol.00030.2013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Myocardial ischemia-reperfusion (IR) injury can cause ventricular cell death and is a major pathological event leading to morbidity and mortality in those with coronary artery disease. Interestingly, as few as five bouts of exercise on consecutive days can rapidly produce a cardiac phenotype that resists IR-induced myocardial injury. This review summarizes the development of exercise-induced cardioprotection and the mechanisms responsible for this important adaptive response.
Collapse
Affiliation(s)
- Scott K Powers
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
| | | | | | | |
Collapse
|
39
|
Tinker A, Aziz Q, Thomas A. The role of ATP-sensitive potassium channels in cellular function and protection in the cardiovascular system. Br J Pharmacol 2014; 171:12-23. [PMID: 24102106 DOI: 10.1111/bph.12407] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/30/2013] [Accepted: 08/26/2013] [Indexed: 12/14/2022] Open
Abstract
ATP-sensitive potassium channels (K(ATP)) are widely distributed and present in a number of tissues including muscle, pancreatic beta cells and the brain. Their activity is regulated by adenine nucleotides, characteristically being activated by falling ATP and rising ADP levels. Thus, they link cellular metabolism with membrane excitability. Recent studies using genetically modified mice and genomic studies in patients have implicated K(ATP) channels in a number of physiological and pathological processes. In this review, we focus on their role in cellular function and protection particularly in the cardiovascular system.
Collapse
Affiliation(s)
- Andrew Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, London, UK
| | | | | |
Collapse
|
40
|
Zhu Z, Sierra A, Burnett CML, Chen B, Subbotina E, Koganti SRK, Gao Z, Wu Y, Anderson ME, Song LS, Goldhamer DJ, Coetzee WA, Hodgson-Zingman DM, Zingman LV. Sarcolemmal ATP-sensitive potassium channels modulate skeletal muscle function under low-intensity workloads. ACTA ACUST UNITED AC 2013; 143:119-34. [PMID: 24344248 PMCID: PMC3874572 DOI: 10.1085/jgp.201311063] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ATP-sensitive potassium (KATP) channels have the unique ability to adjust membrane excitability and functions in accordance with the metabolic status of the cell. Skeletal muscles are primary sites of activity-related energy consumption and have KATP channels expressed in very high density. Previously, we demonstrated that transgenic mice with skeletal muscle–specific disruption of KATP channel function consume more energy than wild-type littermates. However, how KATP channel activation modulates skeletal muscle resting and action potentials under physiological conditions, particularly low-intensity workloads, and how this can be translated to muscle energy expenditure are yet to be determined. Here, we developed a technique that allows evaluation of skeletal muscle excitability in situ, with minimal disruption of the physiological environment. Isometric twitching of the tibialis anterior muscle at 1 Hz was used as a model of low-intensity physical activity in mice with normal and genetically disrupted KATP channel function. This workload was sufficient to induce KATP channel opening, resulting in membrane hyperpolarization as well as reduction in action potential overshoot and duration. Loss of KATP channel function resulted in increased calcium release and aggravated activity-induced heat production. Thus, this study identifies low-intensity workload as a trigger for opening skeletal muscle KATP channels and establishes that this coupling is important for regulation of myocyte function and thermogenesis. These mechanisms may provide a foundation for novel strategies to combat metabolic derangements when energy conservation or dissipation is required.
Collapse
Affiliation(s)
- Zhiyong Zhu
- Department of Internal Medicine and 2 Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
El Khoury N, Mathieu S, Marger L, Ross J, El Gebeily G, Ethier N, Fiset C. Upregulation of the hyperpolarization-activated current increases pacemaker activity of the sinoatrial node and heart rate during pregnancy in mice. Circulation 2013; 127:2009-20. [PMID: 23609807 DOI: 10.1161/circulationaha.113.001689] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Pregnancy is associated with a faster heart rate (HR), which is a risk factor for arrhythmias. However, the underlying mechanisms for this increased HR are poorly understood. Therefore, this study was performed to gain mechanistic insight into the pregnancy-induced increase in HR. METHODS AND RESULTS Using surface ECG we observed that pregnant (P) mice have faster HR (531±14 beats per minute [bpm]) compared with nonpregnant (NP) mice (470±27 bpm; P<0.03). Results obtained with Langendorff-perfused hearts showed that this difference persisted in the absence of autonomic nervous innervation (NP, 327±16 bpm; P, 385±18 bpm; P<0.02). Spontaneous action potentials of sinoatrial node cells from pregnant mice exhibited higher automaticity (NP, 292±13 bpm; P, 330±12 bpm; P=0.047) and steeper diastolic depolarization (NP, 0.20±0.03 V/s; P, 0.40±0.06 V/s; P=0.004). Pregnancy increased the density of the hyperpolarization-activated current (If) (at -90mV: NP, -15.2±1.0 pA/pF; P, -28.6±2.9 pA/pF; P=0.0002) in sinoatrial node cells. Voltage dependence of the If activation curve and the intracellular cAMP levels were unchanged in sinoatrial node cells of pregnant mice. However, there was a significant increase in HCN2 channel protein expression with no change in HCN4 expression. Maximal depolarizing shift of the If activation curve induced by isoproterenol was attenuated in pregnancy. This reduced response to isoproterenol may be attributable to the lower cAMP sensitivity of HCN2 isoform compared with that of HCN4. CONCLUSIONS This study shows that an increase in If current density contributes to the acceleration of sinoatrial node automaticity and explains, in part, the higher HR observed in pregnancy.
Collapse
Affiliation(s)
- Nabil El Khoury
- Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec, Canada, H1T 1C8
| | | | | | | | | | | | | |
Collapse
|
42
|
Working out the heart: functional remodeling by endurance exercise training. J Mol Cell Cardiol 2013; 60:47-9. [PMID: 23579023 DOI: 10.1016/j.yjmcc.2013.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
|
43
|
Cardiac KATP channel alterations associated with acclimation to hypoxia in goldfish (Carassius auratus L.). Comp Biochem Physiol A Mol Integr Physiol 2013; 164:554-64. [DOI: 10.1016/j.cbpa.2012.12.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/24/2012] [Accepted: 12/25/2012] [Indexed: 01/21/2023]
|
44
|
Sierra A, Zhu Z, Sapay N, Sharotri V, Kline CF, Luczak ED, Subbotina E, Sivaprasadarao A, Snyder PM, Mohler PJ, Anderson ME, Vivaudou M, Zingman LV, Hodgson-Zingman DM. Regulation of cardiac ATP-sensitive potassium channel surface expression by calcium/calmodulin-dependent protein kinase II. J Biol Chem 2012; 288:1568-81. [PMID: 23223335 DOI: 10.1074/jbc.m112.429548] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cardiac ATP-sensitive potassium (K(ATP)) channels are key sensors and effectors of the metabolic status of cardiomyocytes. Alteration in their expression impacts their effectiveness in maintaining cellular energy homeostasis and resistance to injury. We sought to determine how activation of calcium/calmodulin-dependent protein kinase II (CaMKII), a central regulator of calcium signaling, translates into reduced membrane expression and current capacity of cardiac K(ATP) channels. We used real-time monitoring of K(ATP) channel current density, immunohistochemistry, and biotinylation studies in isolated hearts and cardiomyocytes from wild-type and transgenic mice as well as HEK cells expressing wild-type and mutant K(ATP) channel subunits to track the dynamics of K(ATP) channel surface expression. Results showed that activation of CaMKII triggered dynamin-dependent internalization of K(ATP) channels. This process required phosphorylation of threonine at 180 and 224 and an intact (330)YSKF(333) endocytosis motif of the K(ATP) channel Kir6.2 pore-forming subunit. A molecular model of the μ2 subunit of the endocytosis adaptor protein, AP2, complexed with Kir6.2 predicted that μ2 docks by interaction with (330)YSKF(333) and Thr-180 on one and Thr-224 on the adjacent Kir6.2 subunit. Phosphorylation of Thr-180 and Thr-224 would favor interactions with the corresponding arginine- and lysine-rich loops on μ2. We concluded that calcium-dependent activation of CaMKII results in phosphorylation of Kir6.2, which promotes endocytosis of cardiac K(ATP) channel subunits. This mechanism couples the surface expression of cardiac K(ATP) channels with calcium signaling and reveals new targets to improve cardiac energy efficiency and stress resistance.
Collapse
Affiliation(s)
- Ana Sierra
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, Iowa 52242, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Tiscornia GC, Moretta R, Argenziano MA, Amorena CE, Garcia Gras EA. Inhibition of connexin 43 in cardiac muscle during intense physical exercise. Scand J Med Sci Sports 2012. [PMID: 23206241 DOI: 10.1111/sms.12017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Endurance training is accompanied by important adaptations in both cardiovascular and autonomic nervous systems. Previous works have shown that the main component of gap junctions in the ventricular myocardium (connexin 43 (Cx43) can be regulated by adrenergic stimulus. On the other hand, training raises vagal and decreases sympathetic tone, while augmenting myocardial sensitivity to sympathetic stimulation during exercise. We therefore evaluated the regulation of Cx43 expression by sympathetic tone during exercise in trained and sedentary mice. Training induced an increase in the protein level of Cx43 by 45-70% under resting conditions. The expression of Cx43 was inhibited in trained but not in untrained mice in response to a 60 min exercise bout. Normal basal expression was restored after 60 min of resting. Cx43 reached a minimum that was not different from basal expression in untrained mice. In accordance, electrocardiography and action potential analysis did not reveal major electrophysiological implications for the drop in Cx43 abundance in trained-exercise mice. We prevented Cx43 inhibition using propranolol, and observed increased basal mRNA levels of β-adrenergic receptors without significant changes in the ratio β1 to β2. In conclusion, we showed that Cx43 expression is transiently inhibited by β-adrenergic stimulus in trained mice during acute exercise.
Collapse
Affiliation(s)
- G C Tiscornia
- CESyMA, ECyT, National University of San Martin, San Martin, Buenos Aires, Argentina
| | | | | | | | | |
Collapse
|
46
|
Hong M, Bao L, Kefaloyianni E, Agullo-Pascual E, Chkourko H, Foster M, Taskin E, Zhandre M, Reid DA, Rothenberg E, Delmar M, Coetzee WA. Heterogeneity of ATP-sensitive K+ channels in cardiac myocytes: enrichment at the intercalated disk. J Biol Chem 2012; 287:41258-67. [PMID: 23066018 DOI: 10.1074/jbc.m112.412122] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ventricular ATP-sensitive potassium (K(ATP)) channels link intracellular energy metabolism to membrane excitability and contractility. Our recent proteomics experiments identified plakoglobin and plakophilin-2 (PKP2) as putative K(ATP) channel-associated proteins. We investigated whether the association of K(ATP) channel subunits with junctional proteins translates to heterogeneous subcellular distribution within a cardiac myocyte. Co-immunoprecipitation experiments confirmed physical interaction between K(ATP) channels and PKP2 and plakoglobin in rat heart. Immunolocalization experiments demonstrated that K(ATP) channel subunits (Kir6.2 and SUR2A) are expressed at a higher density at the intercalated disk in mouse and rat hearts, where they co-localized with PKP2 and plakoglobin. Super-resolution microscopy demonstrate that K(ATP) channels are clustered within nanometer distances from junctional proteins. The local K(ATP) channel density, recorded in excised inside-out patches, was larger at the cell end when compared with local currents recorded from the cell center. The K(ATP) channel unitary conductance, block by MgATP and activation by MgADP, did not differ between these two locations. Whole cell K(ATP) channel current density (activated by metabolic inhibition) was ∼40% smaller in myocytes from mice haploinsufficient for PKP2. Experiments with excised patches demonstrated that the regional heterogeneity of K(ATP) channels was absent in the PKP2 deficient mice, but the K(ATP) channel unitary conductance and nucleotide sensitivities remained unaltered. Our data demonstrate heterogeneity of K(ATP) channel distribution within a cardiac myocyte. The higher K(ATP) channel density at the intercalated disk implies a possible role at the intercellular junctions during cardiac ischemia.
Collapse
Affiliation(s)
- Miyoun Hong
- Department of Pediatrics, New York University School of Medicine, New York, New York 10016, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Bonilla IM, Belevych AE, Sridhar A, Nishijima Y, Ho HT, He Q, Kukielka M, Terentyev D, Terentyeva R, Liu B, Long VP, Györke S, Carnes CA, Billman GE. Endurance exercise training normalizes repolarization and calcium-handling abnormalities, preventing ventricular fibrillation in a model of sudden cardiac death. J Appl Physiol (1985) 2012; 113:1772-83. [PMID: 23042911 DOI: 10.1152/japplphysiol.00175.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The risk of sudden cardiac death is increased following myocardial infarction. Exercise training reduces arrhythmia susceptibility, but the mechanism is unknown. We used a canine model of sudden cardiac death (healed infarction, with ventricular tachyarrhythmias induced by an exercise plus ischemia test, VF+); we previously reported that endurance exercise training was antiarrhythmic in this model (Billman GE. Am J Physiol Heart Circ Physiol 297: H1171-H1193, 2009). A total of 41 VF+ animals were studied, after random assignment to 10 wk of endurance exercise training (EET; n = 21) or a matched sedentary period (n = 20). Following (>1 wk) the final attempted arrhythmia induction, isolated myocytes were used to test the hypotheses that the endurance exercise-induced antiarrhythmic effects resulted from normalization of cellular electrophysiology and/or normalization of calcium handling. EET prevented VF and shortened in vivo repolarization (P < 0.05). EET normalized action potential duration and variability compared with the sedentary group. EET resulted in a further decrement in transient outward current compared with the sedentary VF+ group (P < 0.05). Sedentary VF+ dogs had a significant reduction in repolarizing K(+) current, which was restored by exercise training (P < 0.05). Compared with controls, myocytes from the sedentary VF+ group displayed calcium alternans, increased calcium spark frequency, and increased phosphorylation of S2814 on ryanodine receptor 2. These abnormalities in intracellular calcium handling were attenuated by exercise training (P < 0.05). Exercise training prevented ischemically induced VF, in association with a combination of beneficial effects on cellular electrophysiology and calcium handling.
Collapse
Affiliation(s)
- Ingrid M Bonilla
- College of Pharmacy, The Ohio State University, Columbus, Ohio 43210, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Van Allen NR, Krafft PR, Leitzke AS, Applegate RL, Tang J, Zhang JH. The role of Volatile Anesthetics in Cardioprotection: a systematic review. Med Gas Res 2012; 2:22. [PMID: 22929111 PMCID: PMC3598931 DOI: 10.1186/2045-9912-2-22] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/10/2012] [Indexed: 02/06/2023] Open
Abstract
This review evaluates the mechanism of volatile anesthetics as cardioprotective agents in both clinical and laboratory research and furthermore assesses possible cardiac side effects upon usage. Cardiac as well as non-cardiac surgery may evoke perioperative adverse events including: ischemia, diverse arrhythmias and reperfusion injury. As volatile anesthetics have cardiovascular effects that can lead to hypotension, clinicians may choose to administer alternative anesthetics to patients with coronary artery disease, particularly if the patient has severe preoperative ischemia or cardiovascular instability. Increasing preclinical evidence demonstrated that administration of inhaled anesthetics - before and during surgery - reduces the degree of ischemia and reperfusion injury to the heart. Recently, this preclinical data has been implemented clinically, and beneficial effects have been found in some studies of patients undergoing coronary artery bypass graft surgery. Administration of volatile anesthetic gases was protective for patients undergoing cardiac surgery through manipulation of the potassium ATP (KATP) channel, mitochondrial permeability transition pore (mPTP), reactive oxygen species (ROS) production, as well as through cytoprotective Akt and extracellular-signal kinases (ERK) pathways. However, as not all studies have demonstrated improved outcomes, the risks for undesirable hemodynamic effects must be weighed against the possible benefits of using volatile anesthetics as a means to provide cardiac protection in patients with coronary artery disease who are undergoing surgery.
Collapse
Affiliation(s)
- Nicole R Van Allen
- Department of Physiology, Loma Linda University School of Medicine, Risley Hall, Room 223, Loma Linda, CA 92354, USA.
| | | | | | | | | | | |
Collapse
|
49
|
Fatima N, Schooley JF, Claycomb WC, Flagg TP. Promoter DNA methylation regulates murine SUR1 (Abcc8) and SUR2 (Abcc9) expression in HL-1 cardiomyocytes. PLoS One 2012; 7:e41533. [PMID: 22844491 PMCID: PMC3402388 DOI: 10.1371/journal.pone.0041533] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 06/27/2012] [Indexed: 01/28/2023] Open
Abstract
Two mammalian genes encode the SURx (SUR1, Abcc8 and SUR2, Abcc9) subunits that combine with Kir6.2 (Kcnj11) subunits to form the ATP-sensitive potassium (KATP) channel in cardiac myocytes. Different isoform combinations endow the channel with distinct physiological and pharmacological properties, and we have recently reported that the molecular composition of sarcolemmal KATP channels is chamber specific in the mouse heart. KATP channel composition is determined by what subunits are expressed in a cell or tissue. In the present study, we explore the role of CpG methylation in regulating SUR1 and SUR2 expression. In HL-1 cardiomyocytes, as in atrial myocytes, SUR1 expression is markedly greater than SUR2. Consistent with CpG methylation-dependent silencing of SUR2 expression, bisulfite sequencing of genomic DNA isolated from HL-1 cells demonstrates that 57.6% of the CpGs in the promoter region of the SUR2 gene are methylated, compared with 0.14% of the the CpG residues in the SUR1 sequence. Moreover, treatment with 10 µM 5-aza-2'-deoxycytidine (Aza-dC) significantly increased both the unmethylated fraction of the SUR2 CpG island and mRNA expression. However, we cannot rule out additional mechanisms of Aza-dC action, as Aza-dC also causes a decrease in SUR1 expression and lower doses of Aza-dC do not alter the unmethylated DNA fraction but do elicit a small increase in SUR2 expression. The conclusion that DNA methylation alone is not the only regulator of SUR subunit expression is also consistent with observations in native myocytes, where the CpG islands of both SUR genes are essentially unmethylated in both atrial and ventricular myocytes. Collectively, these data demonstrate the potential for CpG methylation to regulate SURx subunit expression and raises the possibility that regulated or aberrant CpG methylation might play a role in controlling channel structure and function under different physiological conditions or different species.
Collapse
Affiliation(s)
- Naheed Fatima
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
| | - James F. Schooley
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
| | - Willliam C. Claycomb
- Department of Biochemistry and Molecular Biology, LSU Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Thomas P. Flagg
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
- * E-mail:
| |
Collapse
|
50
|
Zhu Z, Burnett CML, Maksymov G, Stepniak E, Sierra A, Subbotina E, Anderson ME, Coetzee WA, Hodgson-Zingman DM, Zingman LV. Reduction in number of sarcolemmal KATP channels slows cardiac action potential duration shortening under hypoxia. Biochem Biophys Res Commun 2011; 415:637-41. [PMID: 22079630 DOI: 10.1016/j.bbrc.2011.10.125] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 10/26/2011] [Indexed: 12/25/2022]
Abstract
The cardiovascular system operates under demands ranging from conditions of rest to extreme stress. One mechanism of cardiac stress tolerance is action potential duration shortening driven by ATP-sensitive potassium (K(ATP)) channels. K(ATP) channel expression has a significant physiologic impact on action potential duration shortening and myocardial energy consumption in response to physiologic heart rate acceleration. However, the effect of reduced channel expression on action potential duration shortening in response to severe metabolic stress is yet to be established. Here, transgenic mice with myocardium-specific expression of a dominant negative K(ATP) channel subunit were compared with littermate controls. Evaluation of K(ATP) channel whole cell current and channel number/patch was assessed by patch clamp in isolated ventricular cardiomyocytes. Monophasic action potentials were monitored in retrogradely perfused, isolated hearts during the transition to hypoxic perfusate. An 80-85% reduction in cardiac K(ATP) channel current density results in a similar magnitude, but significantly slower rate, of shortening of the ventricular action potential duration in response to severe hypoxia, despite no significant difference in coronary flow. Therefore, the number of functional cardiac sarcolemmal K(ATP) channels is a critical determinant of the rate of adaptation of myocardial membrane excitability, with implications for optimization of cardiac energy consumption and consequent cardioprotection under conditions of severe metabolic stress.
Collapse
Affiliation(s)
- Zhiyong Zhu
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|