1
|
Cardioprotective Mechanisms against Reperfusion Injury in Acute Myocardial Infarction: Targeting Angiotensin II Receptors. Biomedicines 2022; 11:biomedicines11010017. [PMID: 36672525 PMCID: PMC9856001 DOI: 10.3390/biomedicines11010017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/11/2022] [Accepted: 11/13/2022] [Indexed: 12/24/2022] Open
Abstract
Ischemia/reperfusion injury is a process associated with cardiologic interventions, such as percutaneous coronary angioplasty after an acute myocardial infarction. Blood flow restoration causes a quick burst of reactive oxygen species (ROS), which generates multiple organelle damage, leading to the activation of cell death pathways. Therefore, the intervention contributes to a greater necrotic zone, thus increasing the risk of cardiovascular complications. A major cardiovascular ROS source in this setting is the activation of multiple NADPH oxidases, which could result via the occupancy of type 1 angiotensin II receptors (AT1R); hence, the renin angiotensin system (RAS) is associated with the generation of ROS during reperfusion. In addition, ROS can promote the expression of NF-κΒ, a proinflammatory transcription factor. Recent studies have described an intracellular RAS pathway that is associated with increased intramitochondrial ROS through the action of isoform NOX4 of NADPH oxidase, thereby contributing to mitochondrial dysfunction. On the other hand, the angiotensin II/ angiotensin type 2 receptor (Ang II/AT2R) axis exerts its effects by counter-modulating the action of AT1R, by activating endothelial nitric oxide synthase (eNOS) and stimulating cardioprotective pathways such as akt. The aim of this review is to discuss the possible use of AT1R blockers to hamper both the Ang II/AT1R axis and the associated ROS burst. Moreover; we suggest that AT1R antagonist drugs should act synergistically with other cardioprotective agents, such as ascorbic acid, N-acetylcysteine and deferoxamine, leading to an enhanced reduction in the reperfusion injury. This therapy is currently being tested in our laboratory and has shown promising outcomes in experimental studies.
Collapse
|
2
|
Shao X, Zhang X, Zhang R, Zhu R, Hou X, Yi W, Wu F, Hao L, Feng R. The atlas of ACE2 expression in fetal and adult human hearts reveals the potential mechanism of heart injured patients infected with SARS-CoV-2. Am J Physiol Cell Physiol 2022; 322:C723-C738. [PMID: 35138176 PMCID: PMC8977135 DOI: 10.1152/ajpcell.00169.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous studies have shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect host cells through binding to angiotensin I converting enzyme 2 (ACE2) expressing in various tissues and organs. In this study, we deeply analyzed the single-cell expression profiles of ACE2 in fetal and adult human hearts to explore the potential mechanism of SARS-CoV-2 harming the heart. The molecular docking software was used to simulate the binding of SARS-CoV-2 and its variant spike protein with ACE2. The genes closely related to ACE2 in renin-angiotensin system (RAS) were identified by constructing a protein-protein interaction network. Through the analysis of single-cell transcription profiles at different stages of human embryos, we found that the expression level of ACE2 in ventricular myocytes was increased with embryonic development. The results of single-cell sequencing analysis showed that the expression of ACE2 in ventricular myocytes was upregulated in heart failure induced by dilated cardiomyopathy compared with normal hearts. The upregulation of ACE2 increases the risk of infection with SARS-CoV-2 in fetal and adult human hearts. We also further confirmed the expression of ACE2 and ACE2-related genes in normal and SARS-CoV-2-infected human pluripotent stem cell-derived cardiomyocytes. In addition, the pathway analysis revealed that ACE2 may regulate the differently expressed genes in heart failure through calcium signaling pathway and Wnt signaling pathway.
Collapse
Affiliation(s)
- Xiuli Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Xiaolin Zhang
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Ruijia Zhang
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Rongli Zhu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Xiuyang Hou
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Weijue Yi
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Fengmin Wu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Rui Feng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| |
Collapse
|
3
|
Labandeira-Garcia JL, Valenzuela R, Costa-Besada MA, Villar-Cheda B, Rodriguez-Perez AI. The intracellular renin-angiotensin system: Friend or foe. Some light from the dopaminergic neurons. Prog Neurobiol 2020; 199:101919. [PMID: 33039415 PMCID: PMC7543790 DOI: 10.1016/j.pneurobio.2020.101919] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 08/20/2020] [Accepted: 10/04/2020] [Indexed: 12/11/2022]
Abstract
The renin-angiotensin system (RAS) is one of the oldest hormone systems in vertebrate phylogeny. RAS was initially related to regulation of blood pressure and sodium and water homeostasis. However, local or paracrine RAS were later identified in many tissues, including brain, and play a major role in their physiology and pathophysiology. In addition, a major component, ACE2, is the entry receptor for SARS-CoV-2. Overactivation of tissue RAS leads several oxidative stress and inflammatory processes involved in aging-related degenerative changes. In addition, a third level of RAS, the intracellular or intracrine RAS (iRAS), with still unclear functions, has been observed. The possible interaction between the intracellular and extracellular RAS, and particularly the possible deleterious or beneficial effects of the iRAS activation are controversial. The dopaminergic system is particularly interesting to investigate the RAS as important functional interactions between dopamine and RAS have been observed in the brain and several peripheral tissues. Our recent observations in mitochondria and nucleus of dopaminergic neurons may clarify the role of the iRAS. This may be important for the developing of new therapeutic strategies, since the effects on both extracellular and intracellular RAS must be taken into account, and perhaps better understanding of COVID-19 cell mechanisms.
Collapse
Affiliation(s)
- Jose L Labandeira-Garcia
- Laboratory of Cellular and Molecular Neurobiology of Parkinson's Disease, Research Center for Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute (IDIS), University of Santiago de Compostela, Santiago de Compostela, Spain; Networking Research Center on Neurodegenerative Diseases (CiberNed), Madrid, Spain.
| | - Rita Valenzuela
- Laboratory of Cellular and Molecular Neurobiology of Parkinson's Disease, Research Center for Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute (IDIS), University of Santiago de Compostela, Santiago de Compostela, Spain; Networking Research Center on Neurodegenerative Diseases (CiberNed), Madrid, Spain
| | - Maria A Costa-Besada
- Laboratory of Cellular and Molecular Neurobiology of Parkinson's Disease, Research Center for Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute (IDIS), University of Santiago de Compostela, Santiago de Compostela, Spain; Networking Research Center on Neurodegenerative Diseases (CiberNed), Madrid, Spain
| | - Begoña Villar-Cheda
- Laboratory of Cellular and Molecular Neurobiology of Parkinson's Disease, Research Center for Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute (IDIS), University of Santiago de Compostela, Santiago de Compostela, Spain; Networking Research Center on Neurodegenerative Diseases (CiberNed), Madrid, Spain
| | - Ana I Rodriguez-Perez
- Laboratory of Cellular and Molecular Neurobiology of Parkinson's Disease, Research Center for Molecular Medicine and Chronic Diseases (CIMUS), Health Research Institute (IDIS), University of Santiago de Compostela, Santiago de Compostela, Spain; Networking Research Center on Neurodegenerative Diseases (CiberNed), Madrid, Spain
| |
Collapse
|
4
|
Yang M, Zhang S, Liang J, Tang Y, Wang X, Huang C, Zhao Q. Different effects of norepinephrine and nerve growth factor on atrial fibrillation vulnerability. J Cardiol 2019; 74:460-465. [DOI: 10.1016/j.jjcc.2019.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/25/2019] [Accepted: 04/16/2019] [Indexed: 10/26/2022]
|
5
|
Reyes S, Cheng CP, Roberts DJ, Yamashita T, Ahmad S, VonCannon JL, Wright KN, Dell'Italia LJ, Varagic J, Ferrario CM. Angiotensin-(1-12)/chymase axis modulates cardiomyocyte L-type calcium currents in rats expressing human angiotensinogen. Int J Cardiol 2019; 297:104-110. [PMID: 31629566 DOI: 10.1016/j.ijcard.2019.09.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/18/2019] [Accepted: 09/24/2019] [Indexed: 11/27/2022]
Abstract
BACKGROUND Activation of the intracrine renin angiotensin systems (RAS) is increasingly recognized as contributing to human pathologies, yet non-canonical renin-independent mechanisms for angiotensin II (Ang II) biosynthesis remain controversial. Direct Ang II generation from angiotensin-(1-12) [Ang-(1-12)] by chymase is an essential intracrine source for regulation of cardiac function. Using a transgenic rat model that overexpresses the human angiotensinogen gene [TGR(hAGT)L1623] and displays increased cardiac Ang II levels, this study aimed to provide evidence for intracrine activation of L-type calcium currents (ICa-L) mediated by the Ang-(1-12)/chymase axis. METHODS AND RESULTS On patch clamp, ICa-L density was significantly higher in TGR(hAGT)L1623 (-6.4 ± 0.3 pA/pF) compared to Sprague Dawley (SD) cardiomyocytes (-4.8, ± 0.5 pA/pF). Intracellular administration of Ang II and Ang-(1-12) elicited a ICa-L increase in both SD and TGR(hAGT)L1623 cardiomyocytes, albeit blunted in transgenic cells. ICa-L activation by intracellular Ang II and Ang-(1-12) was abolished by the specific Ang II type 1 receptor blocker E-3174. Co-administration of a chymase inhibitor prevented activation of ICa-L by Ang-(1-12). Confocal micrographs revealed abundant chymase (mast cell protease 5) immunoreactive protein in SD and TGR(hAGT)L1623 cardiomyocytes. CONCLUSIONS Our data demonstrate the existence in cardiomyocytes of a calcium channel modulatory activity responsive to Ang II generated by the Ang-(1-12)/chymase axis that signals via intracellular receptors. Chronically elevated Ang II in TGR(hAGT)L1623 hearts leading to increased intracellular calcium through ICa-L suggests that activation of this Ang-(1-12)/chymase-governed cardiac intracrine RAS may contribute to the pathological phenotypes observed in the humanized model of chronic hypertension and cardiac hypertrophy.
Collapse
Affiliation(s)
- Santiago Reyes
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | - Che Ping Cheng
- Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest School of Medicine, Winston Salem, NC, USA
| | - Drew J Roberts
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Tomohisa Yamashita
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Sarfaraz Ahmad
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Jessica L VonCannon
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Kendra N Wright
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Louis J Dell'Italia
- Birmingham Veteran Affairs Medical Center and Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jasmina Varagic
- Department of Surgery and Cardiovascular Sciences Center, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Carlos M Ferrario
- Departments of Surgery, Physiology and Pharmacology, and Social Sciences, Division of Public Health, Wake Forest School of Medicine, Winston-Salem, NC, USA
| |
Collapse
|
6
|
Escobales N, Nuñez RE, Javadov S. Mitochondrial angiotensin receptors and cardioprotective pathways. Am J Physiol Heart Circ Physiol 2019; 316:H1426-H1438. [PMID: 30978131 PMCID: PMC6620675 DOI: 10.1152/ajpheart.00772.2018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/15/2019] [Accepted: 04/01/2019] [Indexed: 12/13/2022]
Abstract
A growing body of data provides strong evidence that intracellular angiotensin II (ANG II) plays an important role in mammalian cell function and is involved in the pathogenesis of human diseases such as hypertension, diabetes, inflammation, fibrosis, arrhythmias, and kidney disease, among others. Recent studies also suggest that intracellular ANG II exerts protective effects in cells during high extracellular levels of the hormone or during chronic stimulation of the local tissue renin-angiotensin system (RAS). Notably, the intracellular RAS (iRAS) described in neurons, fibroblasts, renal cells, and cardiomyocytes provided new insights into regulatory mechanisms mediated by intracellular ANG II type 1 (AT1Rs) and 2 (AT2Rs) receptors, particularly, in mitochondria and nucleus. For instance, ANG II through nuclear AT1Rs promotes protective mechanisms by stimulating the AT2R signaling cascade, which involves mitochondrial AT2Rs and Mas receptors. The stimulation of nuclear ANG II receptors enhances mitochondrial biogenesis through peroxisome proliferator-activated receptor-γ coactivator-1α and increases sirtuins activity, thus protecting the cell against oxidative stress. Recent studies in ANG II-induced preconditioning suggest that plasma membrane AT2R stimulation exerts protective effects against cardiac ischemia-reperfusion by modulating mitochondrial AT1R and AT2R signaling. These studies indicate that iRAS promotes the protection of cells through nuclear AT1R signaling, which, in turn, promotes AT2R-dependent processes in mitochondria. Thus, despite abundant data on the deleterious effects of intracellular ANG II, a growing body of studies also supports a protective role for iRAS that could be of relevance to developing new therapeutic strategies. This review summarizes and discusses previous studies on the role of iRAS, particularly emphasizing the protective and counterbalancing actions of iRAS, mitochondrial ANG II receptors, and their implications for organ protection.
Collapse
Affiliation(s)
- Nelson Escobales
- Department of Physiology, University of Puerto Rico School of Medicine , San Juan, Puerto Rico
| | - Rebeca E Nuñez
- Department of Physiology, University of Puerto Rico School of Medicine , San Juan, Puerto Rico
| | - Sabzali Javadov
- Department of Physiology, University of Puerto Rico School of Medicine , San Juan, Puerto Rico
| |
Collapse
|
7
|
Critical role of angiotensin II type 2 receptors in the control of mitochondrial and cardiac function in angiotensin II-preconditioned rat hearts. Pflugers Arch 2018; 470:1391-1403. [PMID: 29748710 DOI: 10.1007/s00424-018-2153-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/02/2018] [Indexed: 10/16/2022]
Abstract
Angiotensin II preconditioning (APC) involves an angiotensin II type 1 receptor (AT1-R)-dependent translocation of PKCε and survival kinases to the mitochondria leading to cardioprotection after ischemia-reperfusion (IR). However, the role that mitochondrial AT1-Rs and angiotensin II type 2 receptors (AT2-Rs) play in APC is unknown. We investigated whether pretreatment of Langendorff-perfused rat hearts with losartan (L, AT1-R blocker), PD 123,319 (PD, AT2-R blocker), or their combination (L + PD) affects mitochondrial AT1-R, AT2-R, PKCε, PKCδ, Akt, PKG-1, MAPKs (ERK1/2, JNK, p38), mitochondrial respiration, cardiac function, and infarct size (IS). The results indicate that expression of mitochondrial AT1-Rs and AT2-Rs were enhanced by APC 1.91-fold and 2.32-fold, respectively. Expression of AT2-R was abolished by PD but not by L, whereas the AT1-R levels were abrogated by both blockers. The AT1-R response profile to L and PD was also shared by PKCε, Akt, MAPKs, and PKG-1, but not by PKCδ. A marked increase in state 3 (1.84-fold) and respiratory control index (1.86-fold) of mitochondria was observed with PD regardless of L treatment. PD also enhanced the post-ischemic recovery of rate pressure product (RPP) by 74% (p < 0.05) compared with APC alone. Losartan, however, inhibited the (RPP) by 44% (p < 0.05) before IR and reduced the APC-induced increase of post-ischemic cardiac recovery by 73% (p < 0.05). Finally, L enhanced the reduction of IS by APC through a PD-sensitive mechanism. These findings suggest that APC upregulates angiotensin II receptors in mitochondria and that AT2-Rs are cardioprotective through their permissive action on AT1-R signaling and the suppression of cardiac function.
Collapse
|
8
|
Tang J, Li N, Chen X, Gao Q, Zhou X, Zhang Y, Liu B, Sun M, Xu Z. Prenatal Hypoxia Induced Dysfunction in Cerebral Arteries of Offspring Rats. J Am Heart Assoc 2017; 6:e006630. [PMID: 28974495 PMCID: PMC5721865 DOI: 10.1161/jaha.117.006630] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/19/2017] [Indexed: 12/17/2022]
Abstract
BACKGROUND Hypoxia during pregnancy could cause abnormal development and lead to increased risks of vascular diseases in adults. This study determined angiotensin II (AII)-mediated vascular dysfunction in offspring middle cerebral arteries (MCA). METHODS AND RESULTS Pregnant rats were subjected to hypoxia. Vascular tension in offspring MCA by AII with or without inhibitors, calcium channel activities, and endoplasmic reticulum calcium stores were tested. Whole-cell patch clamping was used to investigate voltage-dependent calcium channel currents. mRNA expression was tested using quantitative real-time polymerase chain reaction. AII-mediated MCA constriction was greater in male offspring exposed to prenatal hypoxia. AT1 and AT2 receptors were involved in the altered AII-mediated vasoconstriction. Prenatal hypoxia increased baseline activities of L-type calcium channel currents in MCA smooth muscle cells. However, calcium currents stimulated by AII were not significantly changed, whereas nifedipine inhibited AII-mediated vasoconstrictions in the MCA. Activities of IP3/ryanodine receptor-operated calcium channels, endoplasmic reticulum calcium stores, and sarcoendoplasmic reticulum membrane Ca2+-ATPase were increased. Prenatal hypoxia also caused dysfunction of vasodilatation via the endothelium NO synthase. The mRNA expressions of AT1A, AT1B, AT2R, Cav1.2α1C, Cav3.2α1H, and ryanodine receptor RyR2 were increased in the prenatal-hypoxia group. CONCLUSIONS Hypoxia in pregnancy could induce dysfunction in both contraction and dilation in the offspring MCA. AII-increased constriction in the prenatal-hypoxia group was not mainly dependent on the L-type and T-type calcium channels; it might predominantly rely on the AII receptors, IP3/ryanodine receptors, and the endoplasmic reticulum calcium store as well as calcium ATPase.
Collapse
MESH Headings
- Animals
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Calcium Signaling
- Cerebrovascular Disorders/etiology
- Cerebrovascular Disorders/metabolism
- Cerebrovascular Disorders/physiopathology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Female
- Fetal Hypoxia/complications
- Fetal Hypoxia/metabolism
- Fetal Hypoxia/physiopathology
- Gestational Age
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Membrane Potentials
- Membrane Transport Modulators/pharmacology
- Middle Cerebral Artery/drug effects
- Middle Cerebral Artery/metabolism
- Middle Cerebral Artery/physiopathology
- Pregnancy
- Prenatal Exposure Delayed Effects
- Rats, Sprague-Dawley
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/metabolism
- Ryanodine Receptor Calcium Release Channel/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Vasoconstriction/drug effects
- Vasoconstrictor Agents/pharmacology
- Vasodilation/drug effects
- Vasodilator Agents/pharmacology
Collapse
Affiliation(s)
- Jiaqi Tang
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Na Li
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Xueyi Chen
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Qinqin Gao
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Xiuwen Zhou
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Yingying Zhang
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Bailin Liu
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Miao Sun
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| | - Zhice Xu
- Institute of Fetology, First Hospital of Soochow University, Suzhou, China
| |
Collapse
|
9
|
Prolonged AT 1R activation induces Ca V1.2 channel internalization in rat cardiomyocytes. Sci Rep 2017; 7:10131. [PMID: 28860469 PMCID: PMC5578992 DOI: 10.1038/s41598-017-10474-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 08/10/2017] [Indexed: 12/18/2022] Open
Abstract
The cardiac L-type calcium channel is a multi-subunit complex that requires co-assembling of the pore-forming subunit CaV1.2 with auxiliary subunits CaVα2δ and CaVβ. Its traffic has been shown to be controlled by these subunits and by the activation of various G-protein coupled receptors (GPCR). Here, we explore the consequences of the prolonged activation of angiotensin receptor type 1 (AT1R) over CaV1.2 channel trafficking. Bioluminescence Resonance Energy Transfer (BRET) assay between β-arrestin and L-type channels in angiotensin II-stimulated cells was used to assess the functional consequence of AT1R activation, while immunofluorescence of adult rat cardiomyocytes revealed the effects of GPCR activation on CaV1.2 trafficking. Angiotensin II exposure results in β-arrestin1 recruitment to the channel complex and an apparent loss of CaV1.2 immunostaining at the T-tubules. Accordingly, angiotensin II stimulation causes a decrease in L-type current, Ca2+ transients and myocyte contractility, together with a faster repolarization phase of action potentials. Our results demonstrate that prolonged AT1R activation induces β-arrestin1 recruitment and the subsequent internalization of CaV1.2 channels with a half-dose of AngII on the order of 100 nM, suggesting that this effect depends on local renin-angiotensin system. This novel AT1R-dependent CaV1.2-trafficking modulation likely contributes to angiotensin II-mediated cardiac remodeling.
Collapse
|
10
|
Fattah C, Nather K, McCarroll CS, Hortigon-Vinagre MP, Zamora V, Flores-Munoz M, McArthur L, Zentilin L, Giacca M, Touyz RM, Smith GL, Loughrey CM, Nicklin SA. Gene Therapy With Angiotensin-(1-9) Preserves Left Ventricular Systolic Function After Myocardial Infarction. J Am Coll Cardiol 2017; 68:2652-2666. [PMID: 27978950 PMCID: PMC5158000 DOI: 10.1016/j.jacc.2016.09.946] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 09/08/2016] [Accepted: 09/29/2016] [Indexed: 01/16/2023]
Abstract
Background Angiotensin-(1-9) [Ang-(1-9)] is a novel peptide of the counter-regulatory axis of the renin-angiotensin-aldosterone system previously demonstrated to have therapeutic potential in hypertensive cardiomyopathy when administered via osmotic mini-pump. Here, we investigate whether gene transfer of Ang-(1-9) is cardioprotective in a murine model of myocardial infarction (MI). Objectives The authors evaluated effects of Ang-(1-9) gene therapy on myocardial structural and functional remodeling post-infarction. Methods C57BL/6 mice underwent permanent left anterior descending coronary artery ligation and cardiac function was assessed using echocardiography for 8 weeks followed by a terminal measurement of left ventricular pressure volume loops. Ang-(1-9) was delivered by adeno-associated viral vector via single tail vein injection immediately following induction of MI. Direct effects of Ang-(1-9) on cardiomyocyte excitation/contraction coupling and cardiac contraction were evaluated in isolated mouse and human cardiomyocytes and in an ex vivo Langendorff-perfused whole-heart model. Results Gene delivery of Ang-(1-9) reduced sudden cardiac death post-MI. Pressure volume measurements revealed complete restoration of end-systolic pressure, ejection fraction, end-systolic volume, and the end-diastolic pressure volume relationship by Ang-(1-9) treatment. Stroke volume and cardiac output were significantly increased versus sham. Histological analysis revealed only mild effects on cardiac hypertrophy and fibrosis, but a significant increase in scar thickness. Direct assessment of Ang-(1-9) on isolated cardiomyocytes demonstrated a positive inotropic effect via increasing calcium transient amplitude and contractility. Ang-(1-9) increased contraction in the Langendorff model through a protein kinase A–dependent mechanism. Conclusions Our novel findings showed that Ang-(1-9) gene therapy preserved left ventricular systolic function post-MI, restoring cardiac function. Furthermore, Ang-(1-9) directly affected cardiomyocyte calcium handling through a protein kinase A–dependent mechanism. These data emphasized Ang-(1-9) gene therapy as a potential new strategy in the context of MI.
Collapse
Affiliation(s)
- Caroline Fattah
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Katrin Nather
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Charlotte S McCarroll
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Maria P Hortigon-Vinagre
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Victor Zamora
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Monica Flores-Munoz
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom; Universidad Veracruzana, Xalapa, Mexico
| | - Lisa McArthur
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Lorena Zentilin
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Mauro Giacca
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Rhian M Touyz
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christopher M Loughrey
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Stuart A Nicklin
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom.
| |
Collapse
|
11
|
Bernhem K, Krishnan K, Bondar A, Brismar H, Aperia A, Scott L. AT 1-receptor response to non-saturating Ang-II concentrations is amplified by calcium channel blockers. BMC Cardiovasc Disord 2017; 17:126. [PMID: 28514967 PMCID: PMC5436436 DOI: 10.1186/s12872-017-0562-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/09/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Blockers of angiotensin II type 1 receptor (AT1R) and the voltage gated calcium channel 1.2 (CaV1.2) are commonly used for treatment of hypertension. Yet there is little information about the effect of physiological concentrations of angiotensin II (AngII) on AT1R signaling and whether there is a reciprocal regulation of AT1R signaling by CaV1.2. METHODS To elucidate these questions, we have studied the Ca2+ signaling response to physiological and pharmacological AngII doses in HEK293a cells, vascular smooth muscle cells and cardiomyocytes using a Ca2+ sensitive dye as the principal sensor. Intra-cellular calcium recordings were performed in presence and absence of CaV1.2 blockers. Semi-quantitative imaging methods were used to assess the plasma membrane expression of AT1R and G-protein activation. RESULTS Repeated exposure to pharmacological (100 nM) concentrations of AngII caused, as expected, a down-regulation of the Ca2+ response. In contrast, repeated exposure to physiological (1 nM) AngII concentration resulted in an enhancement of the Ca2+ response. The up-regulation of the Ca2+ response to repeated 1 nM AngII doses and the down-regulation of the Ca2+ response to repeated 100 nM Angll doses were not accompanied by a parallel change of the AT1R plasma membrane expression. The Ca2+ response to 1 nM of AngII was amplified in the presence of therapeutic concentrations of the CaV1.2 blockers, nifedipine and verapamil, in vascular smooth muscle cells, cardiomyocytes and HEK293a cells. Amplification of the AT1R response was also observed following inhibition of the calcium permeable transient receptor potential cation channels, suggesting that the activity of AT1R is sensitive to calcium influx. CONCLUSIONS Our findings have implications for the understanding of hyperactivity of the angiotensin system and for use of Ca2+ channel blockers as mono-therapy in hypertension.
Collapse
Affiliation(s)
- Kristoffer Bernhem
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Kalaiselvan Krishnan
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Alexander Bondar
- Institute of Chemical Biology and Fundamental Medicine, 630090, Novosibirsk, Russia
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, PO Box 1031, 17121, Solna, Sweden.,Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Anita Aperia
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, PO Box 1031, 17121, Solna, Sweden.
| | - Lena Scott
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, PO Box 1031, 17121, Solna, Sweden
| |
Collapse
|
12
|
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia, contributing to increased morbidity and reduced survival through its associations with stroke and heart failure. AF contributes to a four- to fivefold increase in the risk of stroke in the general population and is responsible for 10-15 % of all ischemic strokes. Diagnosis and treatment of AF require considerable health care resources. Current therapies to restore sinus rhythm in AF are suboptimal and are limited either by their pro-arrhythmic effects or by their procedure-related complications. These limitations have necessitated identification of newer therapeutic targets to expand the treatment options. There has been a considerable amount of research interest in investigating the mechanisms of initiation and propagation of AF. Despite extensive research focused on the pathogenesis of AF, a thorough understanding of various pathways mediating initiation and propagation of AF still remains limited. Research efforts focused on the identification of these pathways and molecular mediators have generated a great degree of interest for developing more targeted therapies. This review discusses the potential therapeutic targets and the results from experimental and clinical research investigating these targets.
Collapse
|
13
|
Li YL. Angiotensin II-Superoxide Signaling and Arterial Baroreceptor Function in Type-1 Diabetes Mellitus. JOURNAL OF DIABETES & METABOLISM 2014; Suppl 12:1-6. [PMID: 24567847 DOI: 10.4172/2155-6156.s12-001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Diabetes is a major world health problem. Growing evidence from both clinical trials and animal experiments has clearly confirmed that arterial baroreflex dysfunction is a feature of type 1 diabetes, which links to prognosis and mortality of the type 1 diabetic patients. The arterial baroreflex normally regulates the blood pressure and heart rate through sensing changes of arterial vascular tension by the arterial baroreceptors in the aortic arch and carotid sinus. The aortic baroreceptor neuron located in the nodose ganglia is a primary afferent component of the arterial baroreflex. The functional changes of these neurons are involved in the arterial baroreflex dysfunction in the type 1 diabetes. Type 1 diabetes causes the overexpression and hyperactivation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and further reduces cell excitability of the aortic baroreceptor neurons. The alterations of the HCN channels are regulated by angiotensin II-NADPH oxidase-superoxide signaling in the aortic baroreceptor neurons. From the present review, we can understand the possible mechanisms responsible for the attenuated arterial baroreflex in the type 1 diabetes. These findings are beneficial for improving quality of life and prognosis in patients with the type 1 diabetes mellitus.
Collapse
Affiliation(s)
- Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, USA
| |
Collapse
|
14
|
Abstract
The RAS (renin-angiotensin system) is one of the earliest and most extensively studied hormonal systems. The RAS is an atypical hormonal system in several ways. The major bioactive peptide of the system, AngII (angiotensin II), is neither synthesized in nor targets one specific organ. New research has identified additional peptides with important physiological and pathological roles. More peptides also mean newer enzymatic cascades that generate these peptides and more receptors that mediate their function. In addition, completely different roles of components that constitute the RAS have been uncovered, such as that for prorenin via the prorenin receptor. Complexity of the RAS is enhanced further by the presence of sub-systems in tissues, which act in an autocrine/paracrine manner independent of the endocrine system. The RAS seems relevant at the cellular level, wherein individual cells have a complete system, termed the intracellular RAS. Thus, from cells to tissues to the entire organism, the RAS exhibits continuity while maintaining independent control at different levels. The intracellular RAS is a relatively new concept for the RAS. The present review provides a synopsis of the literature on this system in different tissues.
Collapse
|
15
|
Cliff B, Younis N, Hama S, Soran H. The role of the renin-angiotensin system blocking in the management of atrial fibrillation. J Drug Assess 2012; 1:55-64. [PMID: 27536429 PMCID: PMC4980732 DOI: 10.3109/21556660.2012.672353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/29/2012] [Indexed: 12/02/2022] Open
Abstract
OBJECTIVE To review current available evidence for the role of renin-angiotensin system blockade in the management of atrial fibrillation. METHOD We conducted a PubMed and Medline literature search (January 1980 through July 2011) to identify all clinical trials published in English concerning the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers for primary and secondary prevention of atrial fibrillation. We also discussed renin-angiotensin system and its effects on cellular electrophysiology. CONCLUSION The evidence from the current studies discussed does not provide a firm definitive indication for the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers in the primary or secondary prevention of atrial fibrillation. Nevertheless, modest benefits were observed in patients with left ventricular dysfunction. In view of the possible benefits and the low incidence of side-effects with angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, they can be given to patients with recurrent AF, specifically those with hypertension, heart failure and diabetes mellitus.
Collapse
Affiliation(s)
- Brett Cliff
- University Department of Medicine, Central Manchester University Hospitals NHS Foundation Trust, ManchesterUK
| | - Naveed Younis
- Department of Diabetes and Endocrinology, South Manchester University Hospitals NHS Foundation Trust, ManchesterUK
| | - Salam Hama
- Cardiovascular Research Group, School of Biomedicine, Core Technology Facility (3rd Floor), University of Manchester, ManchesterUK
| | - Handrean Soran
- University Department of Medicine, Central Manchester University Hospitals, ManchesterUK
| |
Collapse
|
16
|
Alvin Z, Laurence GG, Coleman BR, Zhao A, Hajj-Moussa M, Haddad GE. Regulation of L-type inward calcium channel activity by captopril and angiotensin II via the phosphatidyl inositol 3-kinase pathway in cardiomyocytes from volume-overload hypertrophied rat hearts. Can J Physiol Pharmacol 2012; 89:206-15. [PMID: 21423294 DOI: 10.1139/y11-011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Heart failure can be caused by pro-hypertrophic humoral factors such as angiotensin II (Ang II), which regulates protein kinase activities. The intermingled responses of these kinases lead to the early compensated cardiac hypertrophy, but later to the uncompensated phase of heart failure. We have shown that although beneficial, cardiac hypertrophy is associated with modifications in ion channels that are mainly mediated through mitogen-activated protein (MAP) kinase and phosphatidylinositol 3-kinase (PI3K) activation. This study evaluates the control of L-type Ca(2+) current (I(Ca,L)) by the Ang II/PI3K pathway in hypertrophied ventricular myocytes from volume-overload rats using the perforated patch-clamp technique. To assess activation of the I(Ca,L) in cardiomyocytes, voltages of 350 ms in 10 mV increments from a holding potential of -85 mV were applied to cardiocytes, with a pre-pulse to -45 mV for 300 ms. Volume overload-induced hypertrophy reduces I(Ca,L), whereas addition of Ang II alleviates the hypertrophic-induced decrease in a PI3K-dependent manner. Acute administration of Ang II (10(-6) mol/L) to normal adult cardiomyocytes had no effect; however, captopril reduced their basal I(Ca,L). In parallel, captopril regressed the hypertrophy and inverted the Ang II effect on I(Ca,L) seemingly through a PI3K upstream effector. Thus, it seems that regression of cardiac hypertrophy by captopril improved I(Ca,L) partly through PI3K.
Collapse
Affiliation(s)
- Zikiar Alvin
- Department of Physiology and Biophysics, College of Medicine, Howard University, WA 20059, USA
| | | | | | | | | | | |
Collapse
|
17
|
Tadevosyan A, Vaniotis G, Allen BG, Hébert TE, Nattel S. G protein-coupled receptor signalling in the cardiac nuclear membrane: evidence and possible roles in physiological and pathophysiological function. J Physiol 2011; 590:1313-30. [PMID: 22183719 DOI: 10.1113/jphysiol.2011.222794] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) play key physiological roles in numerous tissues, including the heart, and their dysfunction influences a wide range of cardiovascular diseases. Recently, the notion of nuclear localization and action of GPCRs has become more widely accepted. Nuclear-localized receptors may regulate distinct signalling pathways, suggesting that the biological responses mediated by GPCRs are not solely initiated at the cell surface but may result from the integration of extracellular and intracellular signalling pathways. Many of the observed nuclear effects are not prevented by classical inhibitors that exclusively target cell surface receptors, presumably because of their structures, lipophilic properties, or affinity for nuclear receptors. In this topical review, we discuss specifically how angiotensin-II, endothelin, β-adrenergic and opioid receptors located on the nuclear envelope activate signalling pathways, which convert intracrine stimuli into acute responses such as generation of second messengers and direct genomic effects, and thereby participate in the development of cardiovascular disorders.
Collapse
Affiliation(s)
- Artavazd Tadevosyan
- Department of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
| | | | | | | | | |
Collapse
|
18
|
Rivard K, Grandy SA, Douillette A, Paradis P, Nemer M, Allen BG, Fiset C. Overexpression of type 1 angiotensin II receptors impairs excitation-contraction coupling in the mouse heart. Am J Physiol Heart Circ Physiol 2011; 301:H2018-27. [DOI: 10.1152/ajpheart.01092.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transgenic mice that overexpress human type 1 angiotensin II receptor (AT1R) in the heart develop cardiac hypertrophy. Previously, we have shown that in 6-mo AT1R mice, which exhibit significant cardiac remodeling, fractional shortening is decreased. However, it is not clear whether altered contractility is attributable to AT1R overexpression or is secondary to cardiac hypertrophy/remodeling. Thus the present study characterized the effects of AT1R overexpression on ventricular L-type Ca2+ currents ( ICaL), cell shortening, and Ca2+ handling in 50-day and 6-mo-old male AT1R mice. Echocardiography showed there was no evidence of cardiac hypertrophy in 50-day AT1R mice but that fractional shortening was decreased. Cellular experiments showed that cell shortening, ICaL, and Cav1.2 mRNA expression were significantly reduced in 50-day and 6-mo-old AT1R mice compared with controls. In addition, Ca2+ transients and caffeine-induced Ca2+ transients were reduced whereas the time to 90% Ca2+ transient decay was prolonged in both age groups of AT1R mice. Western blot analysis revealed that sarcoplasmic reticulum Ca2+-ATPase and Na+/Ca2+ exchanger protein expression was significantly decreased in 50-day and 6-mo AT1R mice. Overall, the data show that cardiac contractility and the mechanisms that underlie excitation-contraction coupling are altered in AT1R mice. Furthermore, since the alterations in contractility occur before the development of cardiac hypertrophy, it is likely that these changes are attributable to the increased activity of the renin-angiotensin system brought about by AT1R overexpression. Thus it is possible that AT1R blockade may help maintain cardiac contractility in individuals with heart disease.
Collapse
Affiliation(s)
- Katy Rivard
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | - Scott A. Grandy
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | - Annie Douillette
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | | | | | | | - Céline Fiset
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| |
Collapse
|
19
|
Li YL, Zheng H. Angiotensin II-NADPH oxidase-derived superoxide mediates diabetes-attenuated cell excitability of aortic baroreceptor neurons. Am J Physiol Cell Physiol 2011; 301:C1368-77. [PMID: 21940665 DOI: 10.1152/ajpcell.00214.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Overactivation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is involved in diabetes-depressed excitability of aortic baroreceptor neurons in nodose ganglia. This involvement links to the autonomic dysfunction associated with high morbidity and mortality in diabetic patients. The present study examined the effects of an angiotensin II type I receptor (AT(1)R) antagonist (losartan), a NADPH oxidase inhibitor (apocynin), and a superoxide dismutase mimetic (tempol) on the enhanced HCN currents and attenuated cell excitability in diabetic nodose neurons. In sham and streptozotocin-induced type 1 diabetic rats, HCN currents and cell excitability of aortic baroreceptor neurons were recorded by the whole cell patch-clamp technique. The angiotensin II level in nodose ganglia from diabetic rats was higher than that from sham rats (101.6 ± 4.8 vs. 38.9 ± 4.2 pg/mg protein, P < 0.05). Single-cell RT-PCR, Western blot, immunofluorescence staining, and chemiluminescence data showed that mRNA and protein expression of AT(1)R, protein expression of NADPH oxidase components, and superoxide production in nodose neurons were increased in diabetic rats compared with those from sham rats. HCN current density was higher and cell excitability was lower in aortic baroreceptor neurons from diabetic rats than that from sham rats. Losartan (1 μM), apocynin (100 μM), and tempol (1 mM) normalized the enhanced HCN current density and increased the cell excitability in the aortic baroreceptor neurons of diabetic rats. These findings suggest that endogenous angiotensin II-NADPH oxidase-superoxide signaling contributes to the enhanced HCN currents and the depressed cell excitation in the aortic baroreceptor neurons of diabetic rats.
Collapse
Affiliation(s)
- Yu-Long Li
- Dept. of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
| | | |
Collapse
|
20
|
Zhao QY, Huang CX, Jiang H, Okello E, Wang X, Tang YH, Li GS. Acetylcholine-regulated K+ current remodelling in the atrium after myocardial infarction and valsartan administration. Can J Cardiol 2009; 25:e115-8. [PMID: 19340355 DOI: 10.1016/s0828-282x(09)70069-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is a common complication of myocardial infarction (MI). Angiotensin II receptor antagonists prevent the promotion and propagation of AF. However, the activation of the acetylcholine-regulated K(+) current (I(K,ACh)) in the atrium after MI and the effect of valsartan on I(K,ACh) are less understood. METHODS Twenty-four adult rabbits were randomly divided into three groups: sham-operated, MI and MI plus valsartan administration (MI+valsartan). The sham-operated group received a median sternotomy without left ventricular coronary artery ligation. Both the MI group and the MI+valsartan group received a median sternotomy followed by ligation of the midpoint of the left ventricular coronary artery. The MI+valsartan group was administered oral valsartan for 12 weeks. After 12 weeks, the initiation of AF was measured by vagal stimulation followed by quick excision of the heart. I(K,ACh) in the left atrial myocardium was measured by the patch clamp technique. RESULTS AF was induced in four animals in the MI group, two in the sham-operated and two in the MI+valsartan groups, with the total AF duration expectedly longer in the MI group than in the sham-operated and MI+valsartan groups (38 s versus 9 s and 9 s, respectively). Furthermore, the mean (+/- SEM) density of I(K,ACh) increased significantly more in the left atrial myocardia of the MI group than in the sham-operated and the MI+valsartan groups (-13+/-0.42 pA/pF versus -9+/-0.38 pA/pF and -10+/-0.37 pA/pF, respectively at -100 mV; and 4.1+/-0.28 pA/pF versus 3.1+/-0.27 pA/pF and 3.3+/-0.27 pA/pF, respectively at 20 mV; P<0.05). However, there was no statistically significant difference in I(K,ACh) between the sham-operated group and the MI+valsartan group. CONCLUSIONS AF is associated with increased I(K,ACh) after MI. Inhibition of increased IK,ACh may be the mechanism by which valsartan prevents AF following MI.
Collapse
Affiliation(s)
- Qing-yan Zhao
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
PURPOSE OF REVIEW The renin-angiotensin system (RAS) has undergone continuous advancement since the initial identification of renin as a pressor agent. Traditionally considered a circulatory system, the RAS is now known to exist as a tissue system as well. Recently, the tissue RAS has been further categorized as intracellular and extracellular. Owing to the unique location, the intracellular RAS encompasses new components, such as cathepsin D and chymase, which participate in intracellular angiotensin (Ang) II synthesis. In this review, evidence of the intracellular RAS and the mechanism of Ang II synthesis in various cell types will be discussed. RECENT FINDINGS A physiological role for intracellular Ang II in vascular and cardiac cells has recently been demonstrated. Evidence of intracellular Ang II generation has been shown in several cell types, particularly cardiac, renal, and vascular. Importantly, intracellular synthesis of Ang II is more prominent in hyperglycemic conditions and generally involves angiotensin-converting enzyme-dependent and angiotensin-converting enzyme-independent mechanisms. SUMMARY There is significant diversity in the mechanism of intracellular synthesis of Ang II in various cell types and pathological conditions. These observations suggest that a therapeutic intervention to block the RAS should take into consideration the nature of the disorder and the cell type involved.
Collapse
|
22
|
Effects of calcium channel and renin-angiotensin system blockade on intravascular and neurohormonal mechanisms of hypertensive vascular disease. Am J Hypertens 2008; 21:1076-85. [PMID: 18756260 DOI: 10.1038/ajh.2008.258] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Several classes of antihypertensive drugs have been shown to improve vascular function through mechanisms other than reducing blood pressure (BP) alone. Certain dihydropyridine calcium channel blockers (CCBs) and inhibitors of the renin-angiotensin system (RAS) increase nitric oxide (NO) bioavailability and decrease oxidative stress, thereby improving endothelial activity and vascular function. Pulse wave analyses have shown that these agents reduce the impact of pressure wave reflections on central systolic BP (SBP), consistent with a decrease in arterial stiffness. The complementary vascular mechanisms of these drug classes suggest that combination therapy may be effective for improving clinical outcomes. In animal model studies, combination calcium channel/RAS blockade has been shown to be more effective in improving endothelial dysfunction than treatment with drugs from either class alone. Furthermore, results from recent clinical trials suggest a greater reduction in central aortic SBP, pulse pressure, and cardiovascular events with calcium channel/RAS blockade vs. beta-blocker/diuretic therapy. These studies support the potential benefit of combination calcium channel and RAS blockade in the prevention and treatment of cardiovascular disease.
Collapse
|
23
|
Michael G, Xiao L, Qi XY, Dobrev D, Nattel S. Remodelling of cardiac repolarization: how homeostatic responses can lead to arrhythmogenesis. Cardiovasc Res 2008; 81:491-9. [PMID: 18826964 DOI: 10.1093/cvr/cvn266] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cardiac action potentials (APs) are driven by ionic currents flowing through specific channels and exchangers across cardiomyocyte membranes. Once initiated by rapid Na(+) entry during phase 0, the AP time course is determined by the balance between inward depolarizing currents, carried mainly by Na(+) and Ca(2+), and outward repolarizing currents carried mainly by K(+). K(+) currents play a major role in repolarization. The loss of a K(+) current can impair repolarization, but there is a redundancy of K(+) currents so that when one K(+) current is dysfunctional, other K(+) currents increase to compensate, a phenomenon called 'repolarization reserve'. Repolarization reserve protects repolarization under conditions that increase inward current or reduce outward current, threatening the balance that governs AP duration. This protection comes at the expense of reduced repolarization reserve, potentially resulting in unexpectedly large AP prolongation and arrhythmogenesis, when an additional repolarization-suppressing intervention is superimposed. The critical role of appropriate repolarization is such that cardiac rhythm stability can be impaired with either abnormally slow or excessively rapid repolarization. In cardiac disease states such as heart failure and atrial fibrillation (AF), changes in ion channel properties appear as part of an adaptive response to maintain function in the face of disease-related stress on the cardiovascular system. However, if the stress is maintained the adaptive ion channel changes may themselves lead to dysfunction, in particular cardiac arrhythmias. The present article reviews ionic remodelling of cardiac repolarization, and focuses on how potentially adaptive repolarization changes with congestive heart failure and AF can have arrhythmogenic consequences.
Collapse
Affiliation(s)
- Georghia Michael
- Department of Medicine, Montreal Heart Institute, 5000 Belanger Street East, Montreal, Quebec, Canada H1T 1C8
| | | | | | | | | |
Collapse
|
24
|
Angiotensinogen and ACE gene polymorphisms and risk of atrial fibrillation in the general population. Pharmacogenet Genomics 2008; 18:525-33. [PMID: 18496132 DOI: 10.1097/fpc.0b013e3282fce3bd] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The renin-angiotensin system may play a role in the pathogenesis of atrial fibrillation, and renin-angiotensin system blockers reduce the risk of atrial fibrillation. We hypothesized that polymorphisms in the angiotensinogen and angiotensin-converting enzyme (ACE) genes encoding proteins in this system predict risk of atrial fibrillation. METHODS AND RESULTS We genotyped 9235 individuals from the Danish general population, The Copenhagen City Heart Study, for the a-20c, g-6a, T174M, and M235T polymorphisms in the angiotensinogen gene and the insertion/deletion (I/D) polymorphism in the ACE gene; rare allele frequencies were 0.16, 0.40, 0.12, 0.41, and 0.49, respectively. Participants had sinus rhythm at inclusion. During 26 years of follow-up, 968 individuals developed atrial fibrillation. Multifactorially adjusted hazard ratios for atrial fibrillation for a-20c ac and cc versus aa genotype were 1.1(95% confidence interval: 1.0-1.3; P=0.05) and 1.5(1.1-2.1; P=0.01). Compared with double noncarriers (angiotensinogen -20aa and ACE II), double heterozygotes (ac-I/D genotype), and double homozygotes (cc-DD) had hazard ratios for atrial fibrillation of 1.2(0.9-1.6; P=0.06) and 2.4(1.4-4.1; P=0.001). a-20c cc homozygotes above 70 years of age who were overweight, severely hypertensive, and had heart failure, had an absolute 10-year risk of atrial fibrillation of 61%. CONCLUSION Angiotensinogen a-20c genotype alone and in combination with ACE I/D genotype predicts an increased risk of atrial fibrillation. Therefore, genetic variation in the renin-angiotensin system may influence effect of renin-angiotensin system blockers on atrial fibrillation.
Collapse
|
25
|
Eplerenone inhibits the intracrine and extracellular actions of angiotensin II on the inward calcium current in the failing heart. On the presence of an intracrine renin angiotensin aldosterone system. ACTA ACUST UNITED AC 2008; 151:54-60. [PMID: 18585409 DOI: 10.1016/j.regpep.2008.06.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 05/13/2008] [Accepted: 06/01/2008] [Indexed: 12/20/2022]
Abstract
UNLABELLED The influence of chronic administration of eplerenone on the intracrine as well as on the extracellular action of angiotensin II (Ang II) on L-type inward calcium current was investigated in the failing heart of cardiomyopathic hamsters (TO-2).For this, eplerenone (200 mg/kg/day) was administered orally to 2 month-old cardiomyopathic hamsters for a period of 3 months. Measurements of the peak inward calcium current (I(Ca)) was performed in single cells under voltage clamp using the whole cell configuration. The results indicated that eplerenone suppressed the intracrine action of Ang II (10(-)(8) M) on peak I(Ca) density. Moreover, the intracellular dialysis of the peptide did not change the time course of I(Ca) inactivation in animals treated chronically with eplerenone. The extracellular administration of Ang II (10(-)(8) M) incremented the peak I(Ca) density by only 20+/-8% (n=30) compared with 38+/-4% (n=35) (P<0.05) obtained in age-matched cardiomyopathic hamsters not exposed to eplerenone. Interestingly, the inhibitory of eplerenone (10(-7) M) on the intracrine action of Ang II was also found, in vitro, but required an incubation period of, at least, 24 h. The inhibitory action of eplerenone on the intracellular action of Ang II was partially reversed by exposing the eplerenone-treated cells to aldosterone (10 nM) for a period of 24 h what supports the view that: a) the mineralocorticoid receptor(MR) was involved in the modulation of the intracrine action of the peptide; b) the effect of eplerenone on the intracrine as well as on the extracellular action of Ang II was related ,in part, to a decreased expression of membrane-bound and intracellular AT1 receptors. IN CONCLUSION a) eplerenone inhibits the intracrine action of Ang II on inward calcium current and reduces drastically the effect of extracellular Ang II on I(Ca); b) aldosterone is able to revert the effect of eplerenone; c) the mineralocorticoid receptor is an essential component of the intracrine renin angiotensin aldosterone system.
Collapse
|
26
|
Wang YH, Shi CX, Dong F, Sheng JW, Xu YF. Inhibition of the rapid component of the delayed rectifier potassium current in ventricular myocytes by angiotensin II via the AT1 receptor. Br J Pharmacol 2008; 154:429-39. [PMID: 18414380 DOI: 10.1038/bjp.2008.95] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE There is increasing evidence that angiotensin II (Ang II) is associated with the occurrence of ventricular arrhythmias. However, little is known about the electrophysiological effects of Ang II on ventricular repolarization. The rapid component of the delayed rectifier K(+) current (I(Kr)) plays a critical role in cardiac repolarization. Hence, the aim of this study was to assess the effect of Ang II on I(Kr) in guinea-pig ventricular myocytes. EXPERIMENTAL APPROACH The whole-cell patch-clamp technique was used to record I(Kr) in native cardiocytes and in human embryonic kidney (HEK) 293 cells, co-transfected with human ether-a-go-go-related gene (hERG) encoding the alpha-subunit of I(Kr) and the human Ang II type 1 (AT(1)) receptor gene. KEY RESULTS Ang II decreased the amplitude of I(Kr) in a concentration-dependent manner with an IC(50) of 8.9 nM. Action potential durations at 50% (APD(50)) and 90% (APD(90)) repolarization were prolonged 20% and 16%, respectively by Ang II (100 nM). Ang II-induced inhibition of the I(Kr) was abolished by the AT(1) receptor blocker, losartan (1 muM). Ang II decreased hERG current in HEK293 cells and significantly delayed channel activation, deactivation and recovery from inactivation. Moreover, PKC inhibitors, stausporine and Bis-1, significantly attenuated Ang II-induced inhibition of I(Kr). CONCLUSIONS AND IMPLICATIONS Ang II produces an inhibitory effect on I(Kr)/hERG currents via AT(1) receptors linked to the PKC pathway in ventricular myocytes. This is a potential mechanism by which elevated levels of Ang II are involved in the occurrence of arrhythmias in cardiac hypertrophy and failure.
Collapse
Affiliation(s)
- Y H Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | | | | | | | | |
Collapse
|
27
|
Singh VP, Baker KM, Kumar R. Activation of the intracellular renin-angiotensin system in cardiac fibroblasts by high glucose: role in extracellular matrix production. Am J Physiol Heart Circ Physiol 2008; 294:H1675-84. [PMID: 18296558 DOI: 10.1152/ajpheart.91493.2007] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The occurrence of a functional intracellular renin-angiotensin system (RAS) has emerged as a new paradigm. Recently, we and others demonstrated intracellular synthesis of ANG II in cardiac myocytes and vascular smooth muscle cells that was dramatically stimulated in high glucose conditions. Cardiac fibroblasts significantly contribute to diabetes-induced diastolic dysfunction. The objective of the present study was to determine the existence of the intracellular RAS in cardiac fibroblasts and its role in extracellular matrix deposition. Neonatal rat ventricular fibroblasts were serum starved and exposed to isoproterenol or high glucose in the absence or presence of candesartan, which was used to prevent receptor-mediated uptake of ANG II. Under these conditions, an increase in ANG II levels in the cell lysate represented intracellular synthesis. Both isoproterenol and high glucose significantly increased intracellular ANG II levels. Confocal microscopy revealed perinuclear and nuclear distribution of intracellular ANG II. Consistent with intracellular synthesis, Western analysis showed increased intracellular levels of renin following stimulation with isoproterenol and high glucose. ANG II synthesis was catalyzed by renin and angiotensin-converting enzyme (ACE), but not chymase, as determined using specific inhibitors. High glucose resulted in increased transforming growth factor-beta and collagen-1 synthesis by cardiac fibroblasts that was partially inhibited by candesartan but completely prevented by renin and ACE inhibitors. In conclusion, cardiac fibroblasts contain a functional intracellular RAS that participates in extracellular matrix formation in high glucose conditions, an observation that may be helpful in developing an appropriate therapeutic strategy in diabetic conditions.
Collapse
Affiliation(s)
- Vivek P Singh
- Cardiovascular Research Institute, Texas A&M HSC, Temple, TX 76504, USA
| | | | | |
Collapse
|
28
|
De Mello WC. Opposite effects of angiotensin II and angiotensin (1-7) on impulse propagation, excitability and cardiac arrhythmias. Is the overexpression of ACE2 arrhythmogenic? ACTA ACUST UNITED AC 2008; 153:7-10. [PMID: 18272241 DOI: 10.1016/j.regpep.2007.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 12/21/2007] [Accepted: 12/26/2007] [Indexed: 11/24/2022]
Affiliation(s)
- Walmor C De Mello
- Department of Pharmacology, School of Medicine Medical Sciences Campus, UPR, San Juan, PR 00936-5067, USA.
| |
Collapse
|
29
|
Re RN, Cook JL. Mechanisms of Disease: intracrine physiology in the cardiovascular system. ACTA ACUST UNITED AC 2007; 4:549-57. [PMID: 17893683 DOI: 10.1038/ncpcardio0985] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Accepted: 06/14/2007] [Indexed: 01/24/2023]
Abstract
The field of intracrine physiology attempts to codify the biological actions of intracrines--extracellular signaling proteins or peptides that also operate in the intracellular space, either because they are retained in their cells of synthesis or because they have been internalized by a target cell. Intracrines are structurally diverse; hormones, growth factors, DNA-binding proteins and enzymes can all display intracrine functionality. Here, we review the role of intracrines in the heart and vasculature, including the intracrine actions of renin-angiotensin-system components in cardiac pathology, dynorphin B in cardiac development, and a variety of factors in pathologic and therapeutic angiogenesis. We argue that principles of intracrine physiology can inform our understanding of important pathologic processes such as left ventricular hypertrophy, diabetic cardiomyopathy and arrythmogenesis, and can aid the development of more-effective therapeutic interventions in cardiovascular disease.
Collapse
Affiliation(s)
- Richard N Re
- Research Division, Ochsner Clinic Foundation, 1514 Jefferson Highway, New Orleans, LA 70121, USA.
| | | |
Collapse
|
30
|
Schultz HD, Li YL. Carotid body function in heart failure. Respir Physiol Neurobiol 2007; 157:171-85. [PMID: 17374517 PMCID: PMC1965591 DOI: 10.1016/j.resp.2007.02.011] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 02/07/2007] [Accepted: 02/08/2007] [Indexed: 11/16/2022]
Abstract
In this review, we summarize the present state of knowledge of the functional characteristics of the carotid body (CB) chemoreflex with respect to control of sympathetic nerve activity (SNA) in chronic heart failure (CHF). Evidence from both CHF patients and animal models of CHF has clearly established that the CB chemoreflex is enhanced in CHF and contributes to the tonic elevation in SNA. This adaptive change derives from altered function at the level of both the afferent and central nervous system (CNS) pathways of the reflex arc. At the level of the CB, an elevation in basal afferent discharge occurs under normoxic conditions in CHF rabbits, and the discharge responsiveness to hypoxia is enhanced. Outward voltage-gated K(+) currents (I(K)) are suppressed in CB glomus cells from CHF rabbits, and their sensitivity to hypoxic inhibition is enhanced. These changes in I(K) derive partly from downregulation of nitric oxide synthase (NOS)/NO signaling and upregulation of angiotensin II (Ang II)/Ang II receptor (AT(1)R) signaling in glomus cells. At the level of the CNS, interactions of the enhanced input from CB chemoreceptors with altered input from baroreceptor and cardiac afferent pathways and from central Ang II further enhance sympathetic drive. In addition, impaired function of NO in the paraventricular nucleus of the hypothalamus participates in the increased SNA response to CB chemoreceptor activation. These results underscore the principle that multiple mechanisms involving Ang II and NO at the level of both the CB and CNS represent complementary and perhaps redundant adaptive mechanisms to enhance CB chemoreflex function in CHF.
Collapse
Affiliation(s)
- Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska College of Medicine, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA.
| | | |
Collapse
|
31
|
Tsai CT, Wang DL, Chen WP, Hwang JJ, Hsieh CS, Hsu KL, Tseng CD, Lai LP, Tseng YZ, Chiang FT, Lin JL. Angiotensin II increases expression of alpha1C subunit of L-type calcium channel through a reactive oxygen species and cAMP response element-binding protein-dependent pathway in HL-1 myocytes. Circ Res 2007; 100:1476-85. [PMID: 17463319 DOI: 10.1161/01.res.0000268497.93085.e1] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II) is involved in the pathogenesis of atrial fibrillation (AF). L-type calcium channel (LCC) expression is altered in AF remodeling. We investigated whether Ang II modulates LCC current through transcriptional regulation, by using murine atrial HL-1 cells, which have a spontaneous calcium transient, and an in vivo rat model. Ang II increased LCC alpha1C subunit mRNA and protein levels and LCC current density, which resulted in an augmented calcium transient in atrial myocytes. An approximately 2-kb promoter region of LCC alpha1C subunit gene was cloned to the pGL3 luciferase vector. Ang II significantly increased promoter activity in a concentration- and time-dependent manner. Truncation and mutational analysis of the LCC alpha1C subunit gene promoter showed that cAMP response element (CRE) (-1853 to -1845) was an important cis element in Ang II-induced LCC alpha1C subunit gene expression. Transfection of dominant-negative CRE binding protein (CREB) (pCMV-CREBS133A) abolished the Ang II effect. Ang II (1 micromol/L, 2 hours) induced serine 133 phosphorylation of CREB and binding of CREB to CRE and increased LCC alpha1C subunit gene promoter activity through a protein kinase C/NADPH oxidase/reactive oxygen species pathway, which was blocked by the Ang II type 1 receptor blocker losartan and the antioxidant simvastatin. In the rat model, Ang II infusion increased LCC alpha1C subunit expression and serine 133 phosphorylation of CREB, which were attenuated by oral losartan and simvastatin. In summary, Ang II induced LCC alpha1C subunit expression via a protein kinase C-, reactive oxygen species-, and CREB-dependent pathway and was blocked by losartan and simvastatin.
Collapse
Affiliation(s)
- Chia-Ti Tsai
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Tolstykh G, de Paula PM, Mifflin S. Voltage-dependent calcium currents are enhanced in nucleus of the solitary tract neurons isolated from renal wrap hypertensive rats. Hypertension 2007; 49:1163-9. [PMID: 17372037 DOI: 10.1161/hypertensionaha.106.084004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The nucleus of the solitary tract (NTS) is the central site of termination of baroreceptor afferents. We hypothesize that changes occur in voltage-gated calcium channels (VGCCs) within NTS neurons as a consequence of hypertension. Whole-cell patch-clamp recordings were obtained from adult normotensive (109+/-2 mm Hg; n=6 from 6 sham-operated and 31 nonsurgically treated) and hypertensive (158+/-6 mm Hg; n=24) rats. In some experiments, 4-(4-[dihexadecylamino]styryl)-N-methylpyridinium iodide was applied to the aortic nerve to visualize NTS neurons receiving baroreceptor synaptic contacts. Ba(2+) currents (500 ms; -80 mV prepotential; 500 ms voltage steps in 5-mV increments to +15mV) peaked between -20 and -10 mV and were blocked by 100 mum of Cd(2+). Peak VGCCs were not different comparing non-4-(4-[dihexadecylamino]styryl)-N-methylpyridinium iodide-labeled and 4-(4- [dihexadecylamino]styryl)-N-methylpyridinium iodide-labeled NTS neurons in hypertensive and normotensive rats. The peak VGCC was significantly greater in cells from hypertensive compared with normotensive rats for both non-DiA-labeled (P=0.02) and DiA-labeled (P=0.04) neurons. To separate high-voltage activated (HVA) and low-voltage activated (LVA) components of VGCCs, voltage ramps (-110 mV to +30 mV over 50 ms) were applied from a holding potential of -60 mV (LVA channels inactivated) and a holding potential of -100 mV (both LVA and HVA currents activated). HVA currents were subtracted from HVA+LVA currents to yield the LVA current. Peak LVA currents were not different between hypertensive (8.9+/-0.8 pA/pF) and normotensive (7.8+/-0.6 pA/pF) groups of NTS neurons (P=0.27). These results demonstrate that 4 weeks of renal wrap hypertension induce an increase in Ca(2+) influx through HVA VGCCs in NTS neurons receiving arterial baroreceptor inputs.
Collapse
Affiliation(s)
- Gleb Tolstykh
- University of Texas Health Science Center at San Antonio, TX 78229-3900, USA
| | | | | |
Collapse
|
33
|
Li YL, Schultz HD. Enhanced sensitivity of Kv channels to hypoxia in the rabbit carotid body in heart failure: role of angiotensin II. J Physiol 2006; 575:215-27. [PMID: 16777942 PMCID: PMC1819433 DOI: 10.1113/jphysiol.2006.110700] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Angiotensin II (Ang II) plays an important role in the enhanced chemoreflex function that occurs in congestive heart failure (CHF), but the mechanism of this effect within the carotid body (CB) is not known. We investigated the sensitivity of Ca2+-independent, voltage-gated K+ (Kv) channels to hypoxia in CB glomus cells from CHF rabbits, and whether endogenous angiotensin II (Ang II) modulates this action. Using the conventional whole-cell patch clamp technique, we found that Kv currents (IK) under normoxic conditions were blunted in the CB glomus cells from CHF rabbits compared with sham rabbits. In addition, the inhibition of IK and the decrease of resting membrane potential (RMP) induced by hypoxia were greater in CHF versus sham glomus cells. Ang II, at 100 pM, had no direct effect on IK at constant normoxic PO2, but increased the sensitivity of IK and RMP to hypoxia in sham glomus cells. In CHF glomus cells, an AT1 receptor (AT1R) antagonist, L-158 809 (1 microM), alone did not affect IK at normoxia, but it decreased the sensitivity of IK and RMP to hypoxia. At higher concentrations, Ang II dose dependently (0.1-100 nM) reduced IK under constant normoxic conditions in sham and CHF glomus cells, with threshold concentrations of about 900 and 600 pM, respectively. Immunocytochemical and Western blot assessments demonstrated the down-expression of Kv3.4 but not Kv4.3 channels in CHF glomus cells. These results indicate that: (1) Ang II/AT1R signalling increases the sensitivity of Kv channels to hypoxia in CB glomus cells from CHF rabbits; (2) high concentrations of Ang II (> 1 nM) directly inhibit IK in CB glomus cells from sham and CHF rabbits; (3) changes in Kv channel protein expression (Kv3.4 versus Kv4.3) in the CB glomus cell may contribute to the suppression of IK and enhanced sensitivity of IK to hypoxia in CHF.
Collapse
Affiliation(s)
- Yu-Long Li
- Department of Cellular and Integrative Physiology, University of, Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | | |
Collapse
|
34
|
Abstract
BACKGROUND Evidence is available that activation of the renin-angiotensin system is involved in cardiac remodeling. It is unknown whether renin can change the inward calcium current (ICa) in the failing heart. This problem was investigated in the present study. METHODS Cardiomyocytes were isolated from the ventricle of 4-month-old cardiomyopathic hamsters and measurements of the L-type ICa were performed using the patch-clamp technique in a whole-cell configuration. RESULTS Extracellular renin (128 pmol Ang I/ml per min) plus angiotensinogen (110 pmol angiotensin I generated by renin to exhaustion) incremented the peak ICa density significantly, an effect suppressed by enalapril maleate (10 mol/l) or by losartan (10 mol/l) added to the bath, indicating that the effect of renin plus angiotensinogen was related to the formation of angiotensin I and its conversion to angiotensin II at the surface cell membrane. Renin internalization seems to increment the ICa because intracellular dialysis of renin (128 pmol Ang I/ml per min) plus angiotensinogen (110 pmol angiotensin I generated by renin to exhaustion) also increased the peak ICa density significantly, an effect suppressed by intracellular losartan (10 mol/l) but not by extracellular losartan (10 mol/l). CONCLUSIONS Extracellular renin plus angiotensinogen increases the ICa in isolated myocytes from the failing heart of cardiomyopathic hamsters through the formation of angiotensin II and the activation of angiotensin type 1 receptors at the surface cell membrane. A similar increment of ICa was found with intracellular administration of renin plus angiotensinogen. This finding might indicate that renin internalization is involved in control of inward calcium current in the failing heart.
Collapse
Affiliation(s)
- Walmor C De Mello
- Department of Pharmacology, Medical Sciences Campus, UPR, San Juan, Puerto Rico, USA.
| |
Collapse
|
35
|
Zhai P, Yamamoto M, Galeotti J, Liu J, Masurekar M, Thaisz J, Irie K, Holle E, Yu X, Kupershmidt S, Roden DM, Wagner T, Yatani A, Vatner DE, Vatner SF, Sadoshima J. Cardiac-specific overexpression of AT1 receptor mutant lacking G alpha q/G alpha i coupling causes hypertrophy and bradycardia in transgenic mice. J Clin Invest 2006; 115:3045-56. [PMID: 16276415 PMCID: PMC1265872 DOI: 10.1172/jci25330] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 08/30/2005] [Indexed: 12/25/2022] Open
Abstract
Ang II type 1 (AT1) receptors activate both conventional heterotrimeric G protein-dependent and unconventional G protein-independent mechanisms. We investigated how these different mechanisms activated by AT1 receptors affect growth and death of cardiac myocytes in vivo. Transgenic mice with cardiac-specific overexpression of WT AT1 receptor (AT1-WT; Tg-WT mice) or an AT1 receptor second intracellular loop mutant (AT1-i2m; Tg-i2m mice) selectively activating G(alpha)q/G(alpha)i-independent mechanisms were studied. Tg-i2m mice developed more severe cardiac hypertrophy and bradycardia coupled with lower cardiac function than Tg-WT mice. In contrast, Tg-WT mice exhibited more severe fibrosis and apoptosis than Tg-i2m mice. Chronic Ang II infusion induced greater cardiac hypertrophy in Tg-i2m compared with Tg-WT mice whereas acute Ang II administration caused an increase in heart rate in Tg-WT but not in Tg-i2m mice. Membrane translocation of PKCepsilon, cytoplasmic translocation of G(alpha)q, and nuclear localization of phospho-ERKs were observed only in Tg-WT mice while activation of Src and cytoplasmic accumulation of phospho-ERKs were greater in Tg-i2m mice, consistent with the notion that G(alpha)q/G(alpha)i-independent mechanisms are activated in Tg-i2m mice. Cultured myocytes expressing AT1-i2m exhibited a left and upward shift of the Ang II dose-response curve of hypertrophy compared with those expressing AT1-WT. Thus, the AT1 receptor mediates downstream signaling mechanisms through G(alpha)q/G(alpha)i-dependent and -independent mechanisms, which induce hypertrophy with a distinct phenotype.
Collapse
MESH Headings
- Animals
- Apoptosis/genetics
- Bradycardia/genetics
- Bradycardia/metabolism
- Bradycardia/pathology
- Cells, Cultured
- Electrocardiography
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Fibrosis/genetics
- Fibrosis/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/deficiency
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Mice
- Mice, Transgenic
- Mutation
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phenotype
- Protein Kinase C-epsilon/metabolism
- Rats
- Rats, Wistar
- Receptor, Angiotensin, Type 1/deficiency
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
Collapse
Affiliation(s)
- Peiyong Zhai
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
De Mello WC. Cardiac intracrine renin angiotensin system. Part of genetic reprogramming? ACTA ACUST UNITED AC 2005; 133:10-2. [PMID: 16325280 DOI: 10.1016/j.regpep.2005.09.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Accepted: 09/13/2005] [Indexed: 11/27/2022]
Abstract
The hypothesis that intracrine renin-angiotensin system activated during heart failure is part of the tendency of the heart to return to embryological conditions when organogenesis is possible is presented and discussed. The hypothesis proposes that the change in genetic makeup, which is known to occur during heart failure, includes a drastic change of intercellular chemical and electrical communication such as second messengers and other signal molecules which are involved in cell proliferation and growth. The role of angiotensin II, which is a growth factor, reduces cell coupling in the failing heart through the activation of AT1 receptors and intracellular pathways, such as PKC, MAPK family and increment of intracellular calcium, might play a key role in the genetic reprogramming of the failing heart.
Collapse
Affiliation(s)
- Walmor C De Mello
- Department of Pharmacology, Medical Sciences Campus, UPR, PO Box 365067, San Juan, Puerto Rico.
| |
Collapse
|
37
|
Ehrlich JR, Hohnloser SH, Nattel S. Role of angiotensin system and effects of its inhibition in atrial fibrillation: clinical and experimental evidence. Eur Heart J 2005; 27:512-8. [PMID: 16311236 DOI: 10.1093/eurheartj/ehi668] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Atrial fibrillation (AF) is a common arrhythmia that is difficult to treat. Anti-arrhythmic drug therapy, to maintain sinus-rhythm, is limited by inadequate efficacy and potentially serious adverse effects. There is increasing interest in novel therapeutic approaches that target AF-substrate development. Recent trials suggest that angiotensin converting-enzyme (ACE)-inhibitors and angiotensin-receptor blockers (ARBs) may be useful, particularly in patients with left ventricular hypertrophy or failure. The clinical potential and mechanisms of this approach are under active investigation. Angiotensin-II is involved in remodelling and may have direct electrophysiological actions. Experimental studies show protection from atrial structural and possibly electrical remodelling with ACE-inhibitors and ARBs, as well as potential effects on cardiac ion-channels. This article reviews information pertaining to the clinical use and mechanism of action of ACE-inhibitors and ARBs in AF. A lack of prospective randomized double-blind trials data limits their application in AF patients without another indication for their use, but studies under way may alter this in the near future. This exciting field of investigation may lead to significant improvements in therapeutic options for AF patients.
Collapse
Affiliation(s)
- Joachim R Ehrlich
- Division of Clinical Electrophysiology, J.W. Goethe University, Theodor Stern Kai 7, 60590 Frankfurt, Germany.
| | | | | |
Collapse
|
38
|
|
39
|
Abstract
Angiotensin synthesis at tissue sites is well-established, and depends largely, if not completely, on kidney-derived renin. The exact tissue site of angiotensin generation (extracellular fluid, cell surface, intracellular compartment) is still being debated. In this review, we discuss the various possibilities, taking into consideration the intracellular occurrence/absence of prorenin, renin, angiotensinogen, angiotensin-converting enzyme, and angiotensin receptors; the local activation of prorenin to renin; the differences between in vivo and in vitro studies; and the methodologic difficulties related to angiotensin measurements. It is eventually concluded that angiotensin generation at tissue sites occurs extracellularly, most likely on the cell surface.
Collapse
Affiliation(s)
- Wenxia Chai
- Department of Pharmacology, Room EE1418b, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | | |
Collapse
|