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Minato H, Endo R, Kurata Y, Notsu T, Kinugasa Y, Wakimizu T, Tsuneto M, Shirayoshi Y, Ninomiya H, Yamamoto K, Hisatome I, Otsuki A. Azelnidipine protects HL-1 cardiomyocytes from hypoxia/reoxygenation injury by enhancement of NO production independently of effects on gene expression. Heart Vessels 2024:10.1007/s00380-024-02415-4. [PMID: 38797744 DOI: 10.1007/s00380-024-02415-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 05/15/2024] [Indexed: 05/29/2024]
Abstract
It remains to be elucidated whether Ca2+ antagonists induce pharmacological preconditioning to protect the heart against ischemia/reperfusion injury. The aim of this study was to determine whether and how pretreatment with a Ca2+ antagonist, azelnidipine, could protect cardiomyocytes against hypoxia/reoxygenation (H/R) injury in vitro. Using HL-1 cardiomyocytes, we studied effects of azelnidipine on NO synthase (NOS) expression, NO production, cell death and apoptosis during H/R. Action potential durations (APDs) were determined by the whole-cell patch-clamp technique. Azelnidipine enhanced endothelial NOS phosphorylation and NO production in HL-1 cells under normoxia, which was abolished by a heat shock protein 90 inhibitor, geldanamycin, and an antioxidant, N-acetylcysteine. Pretreatment with azelnidipine reduced cell death and shortened APDs during H/R. These effects of azelnidipine were diminished by a NOS inhibitor, L-NAME, but were influenced by neither a T-type Ca2+ channel inhibitor, NiCl2, nor a N-type Ca2+ channel inhibitor, ω-conotoxin. The azelnidipine-induced reduction in cell death was not significantly enhanced by either additional azelnidipine treatment during H/R or increasing extracellular Ca2+ concentrations. RNA sequence (RNA-seq) data indicated that azelnidipine-induced attenuation of cell death, which depended on enhanced NO production, did not involve any significant modifications of gene expression responsible for the NO/cGMP/PKG pathway. We conclude that pretreatment with azelnidipine protects HL-1 cardiomyocytes against H/R injury via NO-dependent APD shortening and L-type Ca2+ channel blockade independently of effects on gene expression.
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Affiliation(s)
- Hiroyuki Minato
- Department of Anesthesiology, Tottori University Faculty of Medicine, 86 Nishi-Cho, Yonago, 683-8503, Japan
| | - Ryo Endo
- Department of Anesthesiology, Tottori University Faculty of Medicine, 86 Nishi-Cho, Yonago, 683-8503, Japan
| | - Yasutaka Kurata
- Department of Physiology II, Kanazawa Medical University, Ishikawa, 920-0293, Japan.
| | - Tomomi Notsu
- Department of Genomic Medicine and Regenerative Therapy, Tottori University Faculty of Medicine, Yonago, 683-8503, Japan
| | - Yoshiharu Kinugasa
- Department of Cardiovascular Medicine, and Endocrinology and Metabolism, Tottori University Faculty of Medicine, Yonago, 683-8503, Japan
| | - Takayuki Wakimizu
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, 606-8507, Japan
- Takeda-CiRA Joint Program (T-CiRA), Fujisawa, 251-8555, Japan
| | - Motokazu Tsuneto
- Department of Genomic Medicine and Regenerative Therapy, Tottori University Faculty of Medicine, Yonago, 683-8503, Japan
| | - Yasuaki Shirayoshi
- Department of Genomic Medicine and Regenerative Therapy, Tottori University Faculty of Medicine, Yonago, 683-8503, Japan
| | - Haruaki Ninomiya
- Department of Biological Regulation, Tottori University, Yonago, 683-8503, Japan
| | - Kazuhiro Yamamoto
- Department of Cardiovascular Medicine, and Endocrinology and Metabolism, Tottori University Faculty of Medicine, Yonago, 683-8503, Japan
| | - Ichiro Hisatome
- Department of Cardiology, NHO Yonago Medical Center, Yonago, 683-0006, Japan
| | - Akihiro Otsuki
- Department of Anesthesiology, Tottori University Faculty of Medicine, 86 Nishi-Cho, Yonago, 683-8503, Japan
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Regulation of sinoatrial funny channels by cyclic nucleotides: From adrenaline and I K2 to direct binding of ligands to protein subunits. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:12-21. [PMID: 34237319 DOI: 10.1016/j.pbiomolbio.2021.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 06/13/2021] [Accepted: 06/25/2021] [Indexed: 12/27/2022]
Abstract
The funny current, and the HCN channels that form it, are affected by the direct binding of cyclic nucleotides. Binding of these second messengers causes a depolarizing shift of the activation curve, which leads to greater availability of current at physiological membrane voltages. This review outlines a brief history on this regulation and provides some evidence that other cyclic nucleotides, especially cGMP, may be important for the regulation of the funny channel in the heart. Current understanding of the molecular mechanism of cyclic nucleotide regulation is also presented, which includes the notions that full and partial agonism occur as a consequence of negatively cooperative binding. Knowledge gaps, including a potential role of cyclic nucleotide-regulation of the funny current under pathophysiological conditions, are included. The work highlighted here is in dedication to Dario DiFrancesco on his retirement.
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Wang YW, Gao QW, Xiao YJ, Zhu XJ, Gao L, Zhang WH, Wang RR, Chen KS, Liu FM, Huang HL, Chen L. Bay 60-7550, a PDE2 inhibitor, exerts positive inotropic effect of rat heart by increasing PKA-mediated phosphorylation of phospholamban. Eur J Pharmacol 2021; 901:174077. [PMID: 33798601 DOI: 10.1016/j.ejphar.2021.174077] [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: 07/01/2020] [Revised: 03/21/2021] [Accepted: 03/26/2021] [Indexed: 10/21/2022]
Abstract
This study investigated the hemodynamic effect of Bay 60-7550, a phosphodiesterase type 2 (PDE2) inhibitor, in healthy rat hearts both in vivo and ex vivo and its underlying mechanisms. In vivo rat left ventricular pressure-volume loop, Langendorff isolated rat heart, Ca2+ transient of left ventricular myocyte and Western blot experiments were used in this study. The results demonstrated that Bay 60-7550 (1.5 mg/kg, i. p.) increased the in vivo rat heart contractility by enhancing stroke work, cardiac output, stroke volume, end-diastolic volume, heart rate, and ejection fraction. The simultaneous aortic pressure recording indicated that the systolic blood pressure was increased and diastolic blood pressure was decreased by Bay 60-7550. Also, the arterial elastance which is proportional to the peripheral vessel resistance was significantly decreased. Bay 60-7550 (0.001, 0.01, 0.1, 1 μmol/l) also enhanced the left ventricular development pressure in non-paced and paced modes with a decrease of heart rate in non-paced model. Bay 60-7550 (1 μmol/l) increased SERCA2a activity and SR Ca2+ content and reduced SR Ca2+ leak rate. Furthermore, Bay 60-7550 (0.1 μmol/l) increased the phosphorylation of phospholamban at 16-serine without significantly changing the phosphorylation levels of phospholamban at 17-threonine and RyR2. Bay 60-7550 increased the rat heart contractility and reduced peripheral arterial resistance may be mediated by increasing the phosphorylation of phospholamban and dilating peripheral vessels. PDE2 inhibitors which result in a positive inotropic effect and a decrease in peripheral resistance might serve as a target for developing agents for the treatment of heart failure in clinical settings.
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Affiliation(s)
- Yu-Wei Wang
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Qian-Wen Gao
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Yu-Jie Xiao
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xiao-Jia Zhu
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Li Gao
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Wen-Hui Zhang
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Rong-Rong Wang
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Ke-Su Chen
- School of Medicine, Nanjing University, Nanjing 210093, China
| | - Fu-Ming Liu
- First Affiliated Hospital, Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Hui-Li Huang
- Department of Clinical Pharmacy, No. 900 Hospital of the Chinese PLA Joint Support Forces, Fuzhou 350000, China
| | - Long Chen
- National Standard Laboratory of Pharmacology for Chinese Materia Medica, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; Institute of Chinese Medicine of Taizhou China Medical City, Double Tower, China Medical City, Taizhou 225300, China.
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Does cilnidipine, a dual L- and N-type Ca 2+ blocker, shows promise in drug repositioning approaches? Hypertens Res 2020; 43:726-728. [PMID: 32398796 DOI: 10.1038/s41440-020-0452-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 11/09/2022]
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Mayourian J, Ceholski DK, Gonzalez DM, Cashman TJ, Sahoo S, Hajjar RJ, Costa KD. Physiologic, Pathologic, and Therapeutic Paracrine Modulation of Cardiac Excitation-Contraction Coupling. Circ Res 2019; 122:167-183. [PMID: 29301848 DOI: 10.1161/circresaha.117.311589] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cardiac excitation-contraction coupling (ECC) is the orchestrated process of initial myocyte electrical excitation, which leads to calcium entry, intracellular trafficking, and subsequent sarcomere shortening and myofibrillar contraction. Neurohumoral β-adrenergic signaling is a well-established mediator of ECC; other signaling mechanisms, such as paracrine signaling, have also demonstrated significant impact on ECC but are less well understood. For example, resident heart endothelial cells are well-known physiological paracrine modulators of cardiac myocyte ECC mainly via NO and endothelin-1. Moreover, recent studies have demonstrated other resident noncardiomyocyte heart cells (eg, physiological fibroblasts and pathological myofibroblasts), and even experimental cardiotherapeutic cells (eg, mesenchymal stem cells) are also capable of altering cardiomyocyte ECC through paracrine mechanisms. In this review, we first focus on the paracrine-mediated effects of resident and therapeutic noncardiomyocytes on cardiomyocyte hypertrophy, electrophysiology, and calcium handling, each of which can modulate ECC, and then discuss the current knowledge about key paracrine factors and their underlying mechanisms of action. Next, we provide a case example demonstrating the promise of tissue-engineering approaches to study paracrine effects on tissue-level contractility. More specifically, we present new functional and molecular data on the effects of human adult cardiac fibroblast conditioned media on human engineered cardiac tissue contractility and ion channel gene expression that generally agrees with previous murine studies but also suggests possible species-specific differences. By contrast, paracrine secretions by human dermal fibroblasts had no discernible effect on human engineered cardiac tissue contractile function and gene expression. Finally, we discuss systems biology approaches to help identify key stem cell paracrine mediators of ECC and their associated mechanistic pathways. Such integration of tissue-engineering and systems biology methods shows promise to reveal novel insights into paracrine mediators of ECC and their underlying mechanisms of action, ultimately leading to improved cell-based therapies for patients with heart disease.
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Affiliation(s)
- Joshua Mayourian
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Delaine K Ceholski
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - David M Gonzalez
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Timothy J Cashman
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Susmita Sahoo
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Roger J Hajjar
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Kevin D Costa
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY.
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Everything You Always Wanted to Know about β 3-AR * (* But Were Afraid to Ask). Cells 2019; 8:cells8040357. [PMID: 30995798 PMCID: PMC6523418 DOI: 10.3390/cells8040357] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/26/2019] [Accepted: 04/12/2019] [Indexed: 12/22/2022] Open
Abstract
The beta-3 adrenergic receptor (β3-AR) is by far the least studied isotype of the beta-adrenergic sub-family. Despite its study being long hampered by the lack of suitable animal and cellular models and inter-species differences, a substantial body of literature on the subject has built up in the last three decades and the physiology of β3-AR is unraveling quickly. As will become evident in this work, β3-AR is emerging as an appealing target for novel pharmacological approaches in several clinical areas involving metabolic, cardiovascular, urinary, and ocular disease. In this review, we will discuss the most recent advances regarding β3-AR signaling and function and summarize how these findings translate, or may do so, into current clinical practice highlighting β3-AR’s great potential as a novel therapeutic target in a wide range of human conditions.
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Kalla M, Chotalia M, Coughlan C, Hao G, Crabtree MJ, Tomek J, Bub G, Paterson DJ, Herring N. Protection against ventricular fibrillation via cholinergic receptor stimulation and the generation of nitric oxide. J Physiol 2016; 594:3981-92. [PMID: 26752781 PMCID: PMC4794549 DOI: 10.1113/jp271588] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/06/2016] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Animal studies suggest an anti-fibrillatory action of the vagus nerve on the ventricle, although the exact mechanism is controversial. Using a Langendorff perfused rat heart, we show that the acetylcholine analogue carbamylcholine raises ventricular fibrillation threshold (VFT) and flattens the electrical restitution curve. The anti-fibrillatory action of carbamylcholine was prevented by the nicotinic receptor antagonist mecamylamine, inhibitors of neuronal nitric oxide synthase (nNOS) and soluble guanylyl cyclase (sGC), and can be mimicked by the nitric oxide (NO) donor sodium nitroprusside. Carbamylcholine increased NO metabolite content in the coronary effluent and this was prevented by mecamylamine. The anti-fibrillatory action of both carbamylcholine and sodium nitroprusside was ultimately dependent on muscarinic receptor stimulation as all effects were blocked by atropine. These data demonstrate a protective effect of carbamylcholine on VFT that depends upon both muscarinic and nicotinic receptor stimulation, where the generation of NO is likely to be via a neuronal nNOS-sGC dependent pathway. ABSTRACT Implantable cardiac vagal nerve stimulators are a promising treatment for ventricular arrhythmia in patients with heart failure. Animal studies suggest the anti-fibrillatory effect may be nitric oxide (NO) dependent, although the exact site of action is controversial. We investigated whether a stable analogue of acetylcholine could raise ventricular fibrillation threshold (VFT), and whether this was dependent on NO generation and/or muscarinic/nicotinic receptor stimulation. VFT was determined in Langendorff perfused rat hearts by burst pacing until sustained VF was induced. Carbamylcholine (CCh, 200 nmol l(-1) , n = 9) significantly (P < 0.05) reduced heart rate from 292 ± 8 to 224 ± 6 b.p.m. Independent of this heart rate change, CCh caused a significant increase in VFT (control 1.5 ± 0.3 mA, CCh 2.4 ± 0.4 mA, wash 1.1 ± 0.2 mA) and flattened the restitution curve (n = 6) derived from optically mapped action potentials. The effect of CCh on VFT was abolished by a muscarinic (atropine, 0.1 μmol l(-1) , n = 6) or a nicotinic receptor antagonist (mecamylamine, 10 μmol l(-1) , n = 6). CCh significantly increased NOx content in coronary effluent (n = 8), but not in the presence of mecamylamine (n = 8). The neuronal nitric oxide synthase inhibitor AAAN (N-(4S)-4-amino-5-[aminoethyl]aminopentyl-N'-nitroguanidine; 10 μmol l(-1) , n = 6) or soluble guanylate cyclase (sGC) inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 10 μmol l(-1) , n = 6) prevented the rise in VFT with CCh. The NO donor sodium nitrprusside (10 μmol l(-1) , n = 8) mimicked the action of CCh on VFT, an effect that was also blocked by atropine (n = 10). These data demonstrate a protective effect of CCh on VFT that depends upon both muscarinic and nicotinic receptor stimulation, where the generation of NO is likely to be via a neuronal nNOS/sGC-dependent pathway.
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Affiliation(s)
- Manish Kalla
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Minesh Chotalia
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Charles Coughlan
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Guoliang Hao
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Mark J Crabtree
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Jakub Tomek
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Gil Bub
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
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Soler F, Fernández-Belda F, Pérez-Schindler J, Handschin C, Fuente T, Hernandez-Cascales J. PDE2 activity differs in right and left rat ventricular myocardium and differentially regulates β2 adrenoceptor-mediated effects. Exp Biol Med (Maywood) 2014; 240:1205-13. [PMID: 25432985 DOI: 10.1177/1535370214560969] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/30/2014] [Indexed: 11/16/2022] Open
Abstract
The important regulator of cardiac function, cAMP, is hydrolyzed by different cyclic nucleotide phosphodiesterases (PDEs), whose expression and activity are not uniform throughout the heart. Of these enzymes, PDE2 shapes β1 adrenoceptor-dependent cardiac cAMP signaling, both in the right and left ventricular myocardium, but its role in regulating β2 adrenoceptor-mediated responses is less well known. Our aim was to investigate possible differences in PDE2 transcription and activity between right (RV) and left (LV) rat ventricular myocardium, as well as its role in regulating β2 adrenoceptor effects. The free walls of the RV and the LV were obtained from Sprague-Dawley rat hearts. Relative mRNA for PDE2 (quantified by qPCR) and PDE2 activity (evaluated by a colorimetric procedure and using the PDE2 inhibitor EHNA) were determined in RV and LV. Also, β2 adrenoceptor-mediated effects (β2-adrenoceptor agonist salbutamol + β1 adrenoceptor antagonist CGP-20712A) on contractility and cAMP concentrations, in the absence or presence of EHNA, were studied in the RV and LV. PDE2 transcript levels were less abundant in RV than in LV and the contribution of PDE2 to the total PDE activity was around 25% lower in the microsomal fraction of the RV compared with the LV. β2 adrenoceptor activation increased inotropy and cAMP levels in the LV when measured in the presence of EHNA, but no such effects were observed in the RV, either in the presence or absence of EHNA. These results indicate interventricular differences in PDE2 transcript and activity levels, which may distinctly regulate β2 adrenoceptor-mediated contractility and cAMP concentrations in the RV and in the LV of the rat heart.
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Affiliation(s)
- Fernando Soler
- Department of Biochemistry and Molecular Biology A, University of Murcia, 30100 Murcia, Spain
| | | | | | - Christoph Handschin
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Teodomiro Fuente
- Unit of Radiopharmacy, University Hospital Virgen de la Arrixaca, 30120 Murcia, Spain
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Jia Z, Zhen W, Velayutham Anandh Babu P, Liu D. Phytoestrogen genistein protects against endothelial barrier dysfunction in vascular endothelial cells through PKA-mediated suppression of RhoA signaling. Endocrinology 2013; 154:727-37. [PMID: 23254196 PMCID: PMC3548180 DOI: 10.1210/en.2012-1774] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The soy-derived phytoestrogen genistein has received attention for its potential to improve vascular function, but its mechanism remains unclear. Here, we report that genistein at physiologically relevant concentrations (0.1-10 μM) significantly inhibited thrombin-induced increase in endothelial monolayer permeability. Genistein also reduced the formation of stress fibers by thrombin and suppressed thrombin-induced phosphorylation of myosin light chain (MLC) on Ser(19)/Thr(18) in endothelial cells (ECs). Genistein had no effect on resting intracellular [Ca(2+)] or thrombin-induced increase in Ca(2+) mobilization. Addition of the inhibitors of endothelial nitric oxide synthase or estrogen receptor did not alter the protective effect of genistein. RhoA is a small GTPase that plays an important role in actin-myosin contraction and endothelial barrier dysfunction. RhoA inhibitor blocked the protective effect of genistein on endothelial permeability and also ablated thrombin-induced MLC-phosphorylation in ECs. Inhibition of PKA significantly attenuated the effect of genistein on thrombin-induced EC permeability, MLC phosphorylation, and RhoA membrane translocation in ECs. Furthermore, thrombin diminished cAMP production in ECs, which were prevented by treatment with genistein. These findings demonstrated that genistein improves thrombin-induced endothelial barrier dysfunction in ECs through PKA-mediated suppression of RhoA signaling.
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Affiliation(s)
- Zhenquan Jia
- Department of Biology, The University of North Carolina at Greensboro, Greensboro, NC 27412, USA
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Maron BA, Tang SS, Loscalzo J. S-nitrosothiols and the S-nitrosoproteome of the cardiovascular system. Antioxid Redox Signal 2013; 18:270-87. [PMID: 22770551 PMCID: PMC3518544 DOI: 10.1089/ars.2012.4744] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 06/26/2012] [Accepted: 07/08/2012] [Indexed: 12/13/2022]
Abstract
SIGNIFICANCE Since their discovery in the early 1990's, S-nitrosylated proteins have been increasingly recognized as important determinants of many biochemical processes. Specifically, S-nitrosothiols in the cardiovascular system exert many actions, including promoting vasodilation, inhibiting platelet aggregation, and regulating Ca(2+) channel function that influences myocyte contractility and electrophysiologic stability. RECENT ADVANCES Contemporary developments in liquid chromatography-mass spectrometry methods, the development of biotin- and His-tag switch assays, and the availability of cyanide dye-labeling for S-nitrosothiol detection in vitro have increased significantly the identification of a number of cardiovascular protein targets of S-nitrosylation in vivo. CRITICAL ISSUES Recent analyses using modern S-nitrosothiol detection techniques have revealed the mechanistic significance of S-nitrosylation to the pathophysiology of numerous cardiovascular diseases, including essential hypertension, pulmonary hypertension, ischemic heart disease, stroke, and congestive heart failure, among others. FUTURE DIRECTIONS Despite enhanced insight into S-nitrosothiol biochemistry, translating these advances into beneficial pharmacotherapies for patients with cardiovascular diseases remains a primary as-yet unmet goal for investigators within the field.
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Affiliation(s)
- Bradley A Maron
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Choisy SCM, James AF, Hancox JC. Acute desensitization of acetylcholine and endothelin-1 activated inward rectifier K+ current in myocytes from the cardiac atrioventricular node. Biochem Biophys Res Commun 2012; 423:496-502. [PMID: 22683635 PMCID: PMC3400056 DOI: 10.1016/j.bbrc.2012.05.148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 01/30/2023]
Abstract
The atrioventricular node (AVN) is a vital component of the pacemaker-conduction system of the heart, co-ordinating conduction of electrical excitation from cardiac atria to ventricles and acting as a secondary pacemaker. The electrical behaviour of the AVN is modulated by vagal activity via activation of muscarinic potassium current, IKACh. However, it is not yet known if this response exhibits ‘fade’ or desensitization in the AVN, as established for the heart’s primary pacemaker – the sinoatrial node. In this study, acute activation of IKACh in rabbit single AVN cells was investigated using whole-cell patch clamp at 37 °C. 0.1–1 μM acetylcholine (ACh) rapidly activated a robust IKACh in AVN myocytes during a descending voltage-ramp protocol. This response was inhibited by tertiapin-Q (TQ; 300 nM) and by the M2 muscarinic ACh receptor antagonist AFDX-116 (1 μM). During sustained ACh exposure the elicited IKACh exhibited bi-exponential fade (τf of 2.0 s and τs 76.9 s at −120 mV; 1 μM ACh). 10 nM ET-1 elicited a current similar to IKACh, which faded with a mono-exponential time-course (τ of 52.6 s at −120 mV). When ET-1 was applied following ACh, the ET-1 activated response was greatly attenuated, demonstrating that ACh could desensitize the response to ET-1. For neither ACh nor ET-1 was the rate of current fade dependent upon the initial response magnitude, which is inconsistent with K+ flux mediated changes in electrochemical driving force as the underlying mechanism. Collectively, these findings demonstrate that TQ sensitive inwardly rectifying K+ current in cardiac AVN cells, elicited by M2 muscarinic receptor or ET-1 receptor activation, exhibits fade due to rapid desensitization.
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Affiliation(s)
- Stéphanie C M Choisy
- School of Physiology & Pharmacology and Cardiovascular Research Laboratories, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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cGMP-cAMP interplay in cardiac myocytes: a local affair with far-reaching consequences for heart function. Biochem Soc Trans 2012; 40:11-4. [PMID: 22260658 DOI: 10.1042/bst20110655] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
cAMP and cGMP signalling pathways are common targets in the pharmacological treatment of heart failure, and often drugs that modulate the level of these second messengers are simultaneously administered to patients. cGMP can potentially affect cAMP levels by modulating the activity of PDEs (phosphodiesterases), the enzymes that degrade cyclic nucleotides. This biochemical cross-talk provides the means for drugs that increase cGMP to concomitantly affect cAMP signals. Recent studies using FRET (fluorescence resonance energy transfer) reporters and real-time imaging show that, in cardiac myocytes, the interplay between cGMP and cAMP has different outcomes depending on the specific location where the cross-modulation occurs. cGMP can either increase or decrease the cAMP response to catecholamines, based on the cyclase that generates it and on the PDEs associated with each subcellular compartment. cGMP-mediated modulation of cAMP signals has functional relevance as it affects protein phosphorylation downstream of protein kinase A and myocyte contractility. The physical separation of positive and negative modulation of cAMP levels by cGMP offers the previously unrecognized possibility to selectively modulate local cAMP signals to improve the efficacy of therapy.
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Khori V, Alizadeh AM, Yazdi H, Rakhshan E, Mirabbasi A, Changizi S, Mazandarani M, Nayebpour M. Frequency-dependent Electrophysiological Remodeling of the AV Node by Hydroalcohol Extract of Crocus sativus
L. (Saffron) During Experimental Atrial Fibrillation: The Role of Endogenous Nitric Oxide. Phytother Res 2011; 26:826-32. [DOI: 10.1002/ptr.3643] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 07/11/2011] [Accepted: 07/11/2011] [Indexed: 11/06/2022]
Affiliation(s)
- Vahid Khori
- Golestan Cardiovascular Research Center; Golestan University of Medical Sciences; Gorgan Iran
| | | | - Hamidreza Yazdi
- Golestan Cardiovascular Research Center; Golestan University of Medical Sciences; Gorgan Iran
| | - Elnaz Rakhshan
- Golestan Cardiovascular Research Center; Golestan University of Medical Sciences; Gorgan Iran
| | - Abbas Mirabbasi
- Golestan Cardiovascular Research Center; Golestan University of Medical Sciences; Gorgan Iran
| | - Shima Changizi
- Golestan Cardiovascular Research Center; Golestan University of Medical Sciences; Gorgan Iran
| | | | - Mohsen Nayebpour
- Department of Pharmacology, Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
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14
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Nimura A, Sato N, Sakuragi H, Koyama S, Maruyama J, Talib AK, Nakagawa N, Sakamoto N, Ota H, Tanabe Y, Takeuchi T, Kawamura Y, Hasebe N. Recovery of advanced atrioventricular block by cilostazol. Intern Med 2011; 50:1957-61. [PMID: 21921376 DOI: 10.2169/internalmedicine.50.5228] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We describe a case of advanced atrioventricular (AV) block, in which treatment with cilostazol was effective in recovering the AV conduction. The patient was referred to our hospital for close examination of the advanced AV block and permanent pacemaker implantation. Although the patient had experienced third-degree AV block with occasional AV synchrony for more than two days, the AV conduction completely recovered after treatment with oral cilostazol at 200 mg/day. Here we discuss the possible mechanism of the improvement in the AV conduction by cilostazol.
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Affiliation(s)
- Asami Nimura
- Cardiovascular Respiratory and Neurology Division, Department of Internal Medicine, Asahikawa Medical College, Japan
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15
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Tamargo J, Caballero R, Gómez R, Delpón E. Cardiac electrophysiological effects of nitric oxide. Cardiovasc Res 2010; 87:593-600. [PMID: 20587506 DOI: 10.1093/cvr/cvq214] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nitric oxide (NO) synthetized by essentially all cardiac cell types plays a key role in the regulation of cardiac function. Recent evidence shows that NO modulates the activity of cardiac ion channels implicated in the genesis of the cardiac action potential and exerts anti-arrhythmic properties under some circumstances. We review the effects of NO on cardiac ion channels and the signalling pathways, including cGMP-dependent (protein kinase G and cGMP-regulated phosphodiesterases) and cGMP-independent mechanisms (S-nitrosylation and direct effects on G proteins) and finally the role of NO in the genesis of cardiac arrhythmias during ischemia-reperfusion, heart failure, long QT syndrome, atrial fibrillation, and sudden cardiac death.
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Affiliation(s)
- Juan Tamargo
- Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain.
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16
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Lin YK, Lu YY, Chen YC, Chen YJ, Chen SA. Nitroprusside modulates pulmonary vein arrhythmogenic activity. J Biomed Sci 2010; 17:20. [PMID: 20302658 PMCID: PMC2854108 DOI: 10.1186/1423-0127-17-20] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 03/20/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pulmonary veins (PVs) are the most important sources of ectopic beats with the initiation of paroxysmal atrial fibrillation, or the foci of ectopic atrial tachycardia and focal atrial fibrillation. Elimination of nitric oxide (NO) enhances cardiac triggered activity, and NO can decrease PV arrhythmogenesis through mechano-electrical feedback. However, it is not clear whether NO may have direct electrophysiological effects on PV cardiomyocytes. This study is aimed to study the effects of nitroprusside (NO donor), on the ionic currents and arrhythmogenic activity of single cardiomyocytes from the PVs. METHODS Single PV cardiomyocytes were isolated from the canine PVs. The action potential and ionic currents were investigated in isolated single canine PV cardiomyocytes before and after sodium nitroprusside (80 muM,) using the whole-cell patch clamp technique. RESULTS Nitroprusside decreased PV cardiomyocytes spontaneous beating rates from 1.7 +/- 0.3 Hz to 0.5 +/- 0.4 Hz in 9 cells (P < 0.05); suppressed delayed after depolarization in 4 (80%) of 5 PV cardiomyocytes. Nitroprusside inhibited L-type calcium currents, transient outward currents and transient inward current, but increased delayed rectified potassium currents. CONCLUSION Nitroprusside regulates the electrical activity of PV cardiomyocytes, which suggests that NO may play a role in PV arrhythmogenesis.
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Affiliation(s)
- Yung-Kuo Lin
- Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan.
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17
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Yogaratnam JZ, Laden G, Guvendik L, Cowen M, Cale A, Griffin S. Pharmacological Preconditioning With Hyperbaric Oxygen: Can This Therapy Attenuate Myocardial Ischemic Reperfusion Injury and Induce Myocardial Protection via Nitric Oxide? J Surg Res 2008; 149:155-64. [DOI: 10.1016/j.jss.2007.09.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 08/27/2007] [Accepted: 09/04/2007] [Indexed: 11/29/2022]
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18
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Ye CP, Duan SZ, Milstone DS, Mortensen RM. G(o) controls the hyperpolarization-activated current in embryonic stem cell-derived cardiocytes. Am J Physiol Heart Circ Physiol 2007; 294:H979-85. [PMID: 18156202 DOI: 10.1152/ajpheart.00293.2007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hyperpolarization current (I(f)) is an important player in controlling heart rate and is stimulated by cAMP and inhibited by members of the pertussis toxin-sensitive G-protein G(i)/G(o) family. We have successfully derived cardiocytes from embryonic stem cells lacking G(o) or G(i2) and G(i3). We have established that both basal and isoproterenol-stimulated activities of I(f) in these cardiocytes have typical nodal-atrial characteristics and are unaffected by targeted gene inactivation of the G proteins G(o) or G(i2) and G(i3). Under basal conditions, both G(o) and G(i) are required for muscarinic inhibition of I(f) activity via a mechanism that involves the generation of nitric oxide, whereas, with prior stimulation by beta-agonists, only G(o) is required and G(i) and nitric oxide production are not. Our findings establish an essential role for G(o) in the antiadrenergic effect of muscarinic agent on I(f).
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Affiliation(s)
- Chian P Ye
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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19
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Vandeput F, Wolda SL, Krall J, Hambleton R, Uher L, McCaw KN, Radwanski PB, Florio V, Movsesian MA. Cyclic nucleotide phosphodiesterase PDE1C1 in human cardiac myocytes. J Biol Chem 2007; 282:32749-57. [PMID: 17726023 DOI: 10.1074/jbc.m703173200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Isoforms in the PDE1 family of cyclic nucleotide phosphodiesterases were recently found to comprise a significant portion of the cGMP-inhibited cAMP hydrolytic activity in human hearts. We examined the expression of PDE1 isoforms in human myocardium, characterized their catalytic activity, and quantified their contribution to cAMP hydrolytic and cGMP hydrolytic activity in subcellular fractions of this tissue. Western blotting with isoform-selective anti-PDE1 monoclonal antibodies showed PDE1C1 to be the principal isoform expressed in human myocardium. Immunohistochemical analysis showed that PDE1C1 is distributed along the Z-lines and M-lines of cardiac myocytes in a striated pattern that differs from that of the other major dual-specificity cyclic nucleotide phosphodiesterase in human myocardium, PDE3A. Most of the PDE1C1 activity was recovered in soluble fractions of human myocardium. It binds both cAMP and cGMP with K(m) values of approximately 1 microm and hydrolyzes both substrates with similar catalytic rates. PDE1C1 activity in subcellular fractions was quantified using a new PDE1-selective inhibitor, IC295. At substrate concentrations of 0.1 microm, PDE1C1 constitutes the great majority of cAMP hydrolytic and cGMP hydrolytic activity in soluble fractions and the majority of cGMP hydrolytic activity in microsomal fractions, whereas PDE3 constitutes the majority of cAMP hydrolytic activity in microsomal fractions. These results indicate that PDE1C1 is expressed at high levels in human cardiac myocytes with an intracellular distribution distinct from that of PDE3A and that it may have a role in the integration of cGMP-, cAMP- and Ca(2+)-mediated signaling in these cells.
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Affiliation(s)
- Fabrice Vandeput
- Cardiology Section, Veterans Affairs Salt Lake City Health Care System, 500 Foothill Boulevard, Salt Lake City, UT 84148, USA
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20
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Ganzinelli S, Joensen L, Borda E, Bernabeo G, Sterin-Borda L. Mechanisms involved in the regulation of mRNA for M2 muscarinic acetylcholine receptors and endothelial and neuronal NO synthases in rat atria. Br J Pharmacol 2007; 151:175-85. [PMID: 17384670 PMCID: PMC2013945 DOI: 10.1038/sj.bjp.0707180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Agonists of the M(2) muscarinic acetylcholine receptor (mAChR) increase mRNA for this receptor and mRNA for endothelial and neuronal isoforms of NO synthase (eNOS or nNOS). Here we examine the different signalling pathways involved in such events in rat cardiac atria. EXPERIMENTAL APPROACH In isolated atria, the effects of carbachol on mRNA for M(2) receptors, eNOS and nNOS were measured along with changes in phosphoinositide (PI) turnover, translocation of protein kinase C (PKC), NOS activity and atrial contractility. KEY RESULTS Carbachol increased mRNA for M(2) receptors, activation of PI turnover, translocation of PKC and NOS activity and decreased atrial contractility. Inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), NOS and PKC prevented the carbachol-dependent increase in mRNA for M(2) receptors. These inhibitors also attenuated the carbachol induced increase in nNOS- and eNOS-mRNA levels. Inhibition of nNOS shifted the dose response curve of carbachol on contractility to the right, whereas inhibition of eNOS shifted it to the left. CONCLUSIONS AND IMPLICATIONS From our results, activation of M(2) receptors induced nNOS and eNOS expression and activation of NOS up-regulated M(2) receptor gene expression. The signalling pathways involved included stimulation of PI turnover via PLC activation, CaM and PKC. nNOS and eNOS mediated opposing effects on the negative inotropic effect in atria, induced by stimulation of M(2) receptors. These results may contribute to a better understanding of the effects and side effects of cholinomimetic treatment in patients with cardiac neuromyopathy.
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Affiliation(s)
- S Ganzinelli
- Department of Pharmacology, School of Dentistry, University of Buenos Aires and Argentine National Research Council Buenos Aires, Argentina
| | - L Joensen
- Department of Pharmacology, School of Dentistry, University of Buenos Aires and Argentine National Research Council Buenos Aires, Argentina
| | - E Borda
- Department of Pharmacology, School of Dentistry, University of Buenos Aires and Argentine National Research Council Buenos Aires, Argentina
| | - G Bernabeo
- Department of Pharmacology, School of Dentistry, University of Buenos Aires and Argentine National Research Council Buenos Aires, Argentina
| | - L Sterin-Borda
- Department of Pharmacology, School of Dentistry, University of Buenos Aires and Argentine National Research Council Buenos Aires, Argentina
- Author for correspondence:
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21
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du Toit EF, Genade S, Carlini S, Moolman JA, Brunner F, Lochner A. Efficacy of ischaemic preconditioning in the eNOS overexpressed working mouse heart model. Eur J Pharmacol 2006; 556:115-20. [PMID: 17157294 DOI: 10.1016/j.ejphar.2006.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 10/25/2006] [Accepted: 11/02/2006] [Indexed: 11/17/2022]
Abstract
We recently demonstrated that exogenous nitric oxide (NO) acts as a trigger for preconditioning in the isolated rat heart model. There is however little data concerning the effects of elevated cardiac endothelial nitric oxide synthase (eNOS) expression on myocardial tolerance to ischaemia. Similarly, the effects of gender and eNOS overexpression on ischaemic preconditioning is unknown. We hypothesized that: 1) eNOS overexpression increases myocardial tolerance to ischaemia, and, 2) eNOS overexpressed hearts cannot be preconditioned, since the hearts are already maximally protected. Male and female wild-type and transgenic mice that overexpress eNOS exclusively in cardiac myocytes were perfused in the working heart mode with a modified Krebs-Henseleit buffer at a pre-load of 12.5 mm Hg and afterload of 50 mm Hg. Cardiac output, coronary flow, peak aortic systolic pressure and total work were determined before hearts were preconditioned by 4x5 min cycles of ischaemia/reperfusion, and then subjected to 20 min total global ischaemia, followed by reperfusion. Reperfusion function and myocardial infarct size were used as endpoints. Pre-ischaemic mechanical function (rate pressure product and cardiac output) was similar for wild-type and transgenic mice of both sexes. The eNOS overexpressed hearts had smaller infarcts than the hearts from their wild-type littermates (26.9+/-1.4% vs. 37.0+/-2.1% for controls, P<0.05). Preconditioning the eNOS overexpressed hearts resulted in infarct sizes comparable with control non-preconditioned hearts (27.5+/-2.0% vs. 26.9+/-1.4% for controls). Myocardial cGMP levels were elevated during sustained ischaemia in the transgenic hearts when compared with wild-type hearts (22.43+/-1.63 pmol/g ww vs 16.54+/-1.48 pmol/g ww, P<0.05). Preconditioning also elevated myocardial cGMP levels during sustained ischaemia in the wild-type hearts (26.77+/-2.81 pmol/g ww, P<0.05). We conclude that: 1) basal mechanical function is similar for both wild-type and transgenic mice of both sexes, 2) reperfusion function and infarct size was also similar for both sexes under both control conditions and after preconditioning, 3) the transgenic mice are more tolerant of ischaemia as reflected by their smaller myocardial infarcts, and, 4) the eNOS overexpressed mouse heart cannot be preconditioned regardless of whether mechanical function or infarct size is used as an end-point. These hearts may be maximally protected against ischaemia/reperfusion injury by their elevated endogenous NO levels.
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Affiliation(s)
- Eugene F du Toit
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Stellenbosch, South Africa.
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22
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Eldesoky ES. Effect of acute inhibition of nitric oxide synthesis by l-NAME on cardiovascular responses following peripheral autonomic blockade in rabbits. Fundam Clin Pharmacol 2006; 20:239-45. [PMID: 16671958 DOI: 10.1111/j.1472-8206.2006.00405.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pressor and chronotropic responses to acute inhibition of nitric oxide synthase enzyme by N(G)-nitro-L-arginine methyl ester (L-NAME) were studied in anaesthetized rabbits with intact autonomic nervous system (ANS) activity. Also, they were investigated when administration of L-NAME was preceded by peripheral autonomic blockade. Autonomic blockade had different forms: ganglionic (hexamethonium-induced), post-ganglionic beta-adrenergic blockade (propranolol induced), parasympathetic blockade (atropine induced), and complete autonomic blockade by coadministration of hexamethonium and atropine simultaneously. L-NAME injected intravenously (10 mg/kg) in animals with intact and blocked autonomic activity induced a pressor response. This pressor response was accompanied by bradycardia in rabbits with either intact autonomic activity or hexamethonium-induced ganglionic blockade. L-NAME exerted no effect on heart rate in animals with beta-adrenergic blockade or parasympathetic blockade. In rabbits with complete autonomic blockade, L-NAME evoked tachycardia. These experiments indicate that L-NAME-induced hypertension is not relying only on ANS. Also, L-NAME-induced tachycardia in rabbits treated with atropine plus hexamethonium suggests other humoral mechanisms that may be involved in the L-NAME induced chronotropic response.
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Affiliation(s)
- Ehab S Eldesoky
- Pharmacology Department, Faculty of Medicine, Assiut University, Assiut 71515, Egypt.
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23
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Dynnik VV, Grushin KS, Korystova AF, Nenov MN, Murashov AN, Kokoz YM. Stabilizing role of arginine and NO in the regulation of voltage-sensitive L-type Ca2+ current in cardiocytes. DOKL BIOCHEM BIOPHYS 2006; 404:353-6. [PMID: 16392755 DOI: 10.1007/s10628-005-0112-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- V V Dynnik
- Institute of Theoretical and Experimental Biology, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia
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24
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Zhu YZ, Chong CL, Chuah SC, Huang SH, Nai HS, Tong HT, Whiteman M, Moore PK. Cardioprotective effects of nitroparacetamol and paracetamol in acute phase of myocardial infarction in experimental rats. Am J Physiol Heart Circ Physiol 2005; 290:H517-24. [PMID: 16172162 DOI: 10.1152/ajpheart.00572.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We aimed to determine whether nitroparacetamol (NO-paracetamol) and paracetamol exhibit cardioprotective effects. Myocardial infarction (MI) was induced in rats, and drug treatment was started 1 wk before surgery. Mortality rate and infarct size at 2 days after MI were compared. Treatment groups included vehicle (saline), paracetamol (5 mg x kg(-1) x day(-1)) and NO-paracetamol (15 mg x kg(-1) x day(-1)). Mortality rates for vehicle (n = 80), paracetamol (n = 79), and NO-paracetamol (n = 76) groups were 37.5%, 21.5%, and 26.3%, respectively. Infarct size for the vehicle group was 44.8% (+/-6.1%) of the left ventricle (LV). For the paracetamol and NO-paracetamol groups, infarct size was 31.3% (+/-5.6%) and 30.7% (+/-8.1%) of the LV, respectively. Both paracetamol- and NO-paracetamol-treated groups showed increased activities of catalase and SOD compared with the vehicle group. They could attenuate endothelial, inducible, and neuronal nitric oxide synthase and cyclooxygenase-1 and -2 gene expression after MI. The observation indicates the potential clinical significance of the cardioprotective effects of these drugs.
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Affiliation(s)
- Yi Zhun Zhu
- Dept. of Pharmacology, National Univ. of Singapore, Singapore 117597.
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25
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Carlson DL, Willis MS, White DJ, Horton JW, Giroir BP. Tumor necrosis factor-alpha-induced caspase activation mediates endotoxin-related cardiac dysfunction. Crit Care Med 2005; 33:1021-8. [PMID: 15891331 DOI: 10.1097/01.ccm.0000163398.79679.66] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Sepsis-induced cardiac dysfunction is a serious clinical syndrome characterized by hypotension, decreased systemic vascular resistance, and elevated cardiac index. Although cytokines such as tumor necrosis factor (TNF)-alpha have been shown to play a significant role early in this response, the downstream effects of TNF-alpha signaling on cardiac function, specifically its relationship to apoptosis, have not been fully elucidated. DESIGN Previous studies from our laboratory have identified endotoxin-induced apoptosis in cardiac cells in vitro. To further determine the role of lipopolysaccharide-induced apoptosis in vivo, mice were injected intraperitoneally with lipopolysaccharide (4 mg/kg), and cardiac apoptosis was detected and inhibited using a broad-spectrum caspase inhibitor. SETTING University research laboratory. SUBJECTS Adult male wild-type (B6:129PF1/J) and TNF receptor 1/receptor 2 (TNFR-1/2) knockout mice (B6;129S-Tnfrsf1aTnfrsf1b). INTERVENTIONS We sought to determine the dependence of cardiac apoptosis on TNF-alpha signaling and determine the physiologic role of caspase activation on lipopolysaccharide-induced cardiac dysfunction. MEASUREMENTS AND MAIN RESULTS Cardiac apoptosis was determined at baseline and at 2, 4, 8, and 24 hrs by detection of capase-3 and -8 activity, cytoplasmic levels of Bax/Bcl-2, cleaved caspase-3 immunohistochemistry, and terminal deoxynucleotidyl transferase UTP nick-end labeling (TUNEL) staining of histologic sections in wild-type and TNFR-1/2 knockout mice. To determine the role of caspase activation in lipopolysaccharide-induced cardiac dysfunction, a broad-spectrum caspase inhibitor Z-Val-Ala-Asp (ome)-FMK (sad) was given, and cardiac function was determined in isolated beating hearts (Langendorff preparation). Our experiments determined that caspase-3-dependent apoptosis was active in cardiac tissue by 2 hrs and that this activation was completely mediated by TNFR-1/2. The Bax/Bcl-2 ratios supported the finding and time course of apoptosis, whereas TUNEL staining of cardiac tissue sections identified sporadic apoptotic ventricular cells. The administration of zVAD significantly inhibited myocardial caspase-3 activity and preserved cardiac physiologic function (Langendorff preparation). CONCLUSIONS Endotoxin induces a TNF-alpha-dependent apoptotic cascade in the myocardium, which contributes to the development of cardiac dysfunction.
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Affiliation(s)
- Deborah L Carlson
- Department of Pediatrics, University of Texas Southwestern, Dallas, TX, USA
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26
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Grassi C, D'Ascenzo M, Azzena GB. Modulation of Ca(v)1 and Ca(v)2.2 channels induced by nitric oxide via cGMP-dependent protein kinase. Neurochem Int 2004; 45:885-93. [PMID: 15312983 DOI: 10.1016/j.neuint.2004.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The unconventional gaseous transmitter nitric oxide (NO) markedly influences most of mechanisms involved in the regulation of intracellular Ca2+ homeostasis. In excitable cells, Ca2+ signaling mainly depends on the activity of voltage-gated Ca2+ channels (VGCCs). In the present paper, we will review data from our laboratory and others characterizing NO-induced modulation of Ca(v)1 (L-type) and Ca(v)2.2 (N-type) channels. In particular, we will explore experimental evidence indicating that NO's inhibition of channel gating is produced via cGMP-dependent protein kinase and examine some of the numerous cell functions that are potentially influenced by the action of NO on Ca2+ channels.
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Affiliation(s)
- Claudio Grassi
- Institute of Human Physiology, Medical School, Catholic University S. Cuore, Largo F. Vito 1, I-00168 Rome, Italy.
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27
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Sears CE, Ashley EA, Casadei B. Nitric oxide control of cardiac function: is neuronal nitric oxide synthase a key component? Philos Trans R Soc Lond B Biol Sci 2004; 359:1021-44. [PMID: 15306414 PMCID: PMC1693378 DOI: 10.1098/rstb.2004.1477] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Nitric oxide (NO) has been shown to regulate cardiac function, both in physiological conditions and in disease states. However, several aspects of NO signalling in the myocardium remain poorly understood. It is becoming increasingly apparent that the disparate functions ascribed to NO result from its generation by different isoforms of the NO synthase (NOS) enzyme, the varying subcellular localization and regulation of NOS isoforms and their effector proteins. Some apparently contrasting findings may have arisen from the use of non-isoform-specific inhibitors of NOS, and from the assumption that NO donors may be able to mimic the actions of endogenously produced NO. In recent years an at least partial explanation for some of the disagreements, although by no means all, may be found from studies that have focused on the role of the neuronal NOS (nNOS) isoform. These data have shown a key role for nNOS in the control of basal and adrenergically stimulated cardiac contractility and in the autonomic control of heart rate. Whether or not the role of nNOS carries implications for cardiovascular disease remains an intriguing possibility requiring future study.
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Affiliation(s)
- Claire E Sears
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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28
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Malan D, Ji GJ, Schmidt A, Addicks K, Hescheler J, Levi RC, Bloch W, Fleischmann BK. Nitric oxide, a key signaling molecule in the murine early embryonic heart. FASEB J 2004; 18:1108-10. [PMID: 15132985 DOI: 10.1096/fj.03-1158fje] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nitric oxide (NO) is thought to play an important role as a signaling molecule in embryonic and adult cardiomyocytes; however, its involvement in muscarinic signaling is still unclear. The aim of the present work was to analyze the muscarinic modulation of the L-type Ca2+ current (ICa) in early- and late-stage embryonic ventricular cardiomyocytes. Muscarinic stimulation depressed basal ICa by 30.1 +/- 3.2% (n=27) in early-stage cardiomyocytes. Pharmacological evidence suggested that the muscarinic modulation was mediated through generation of NO, activation of cGMP-dependent phosphodiesterase (PDE) 2, and ensuing lowering of cyclic AMP/protein kinase A (cAMP/PKA) levels. Conversely, in late-stage cardiomyocytes, muscarinic regulation of ICa occurred in a NO-independent manner via inhibition of prestimulated adenylyl cyclase (AC). To unequivocally prove the involvement of NO and to identify the nitric oxide synthase (NOS) isoform(s), we analyzed muscarinic signaling in embryonic ventricular cardiomyocytes of NOS2 (-/-) and NOS3 (-/-) mice. The early-stage NOS3 (-/-) cardiomyocytes lacked muscarinic modulation, whereas it was preserved in NOS2 (-/-) cells. Moreover, at the late embryonic stage, muscarinic modulation of ICa was intact in both strains. Thus, NO is the key regulator of muscarinic signaling in the early embryonic ventricle, whereas at later stages, signaling occurs through a NO-independent pathway.
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Affiliation(s)
- Daniela Malan
- Department of Animal and Human Biology, INFM University of Turin, Italy
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29
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White AR, Curtis SA, Walker RJ. Evidence for a possible role for nitric oxide in the modulation of heart activity in Achatina fulica and Helix aspersa. Comp Biochem Physiol C Toxicol Pharmacol 2004; 137:95-108. [PMID: 15050921 DOI: 10.1016/j.cca.2003.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 11/24/2003] [Accepted: 11/25/2003] [Indexed: 10/26/2022]
Abstract
The effects of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine, S-nitroso-l-glutathione, sodium nitroprusside and sodium nitrite were investigated on the activity of the isolated hearts of Achatina fulica and Helix aspersa. NO donors inhibited heart activity in a concentration-dependent manner. The only exception was sodium nitroprusside, which excited H. aspersa heart. The inhibitory effects of these NO donors were reduced by the NO scavenger, methylene blue, the guanylyl cyclase inhibitor, 1H-(1,2,4) Oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), and potentiated by 8-Br-cGMP and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Acetylcholine also inhibited the heart activity, and this inhibition was reduced by methylene blue and ODQ. Positive NADPH-diaphorase staining was located in the outer pericardial layer of the heart of A. fulica. The present results provide evidence that NO may modulate the activity of gastropod hearts, and this modulation may modify the inhibitory action of acetylcholine on heart activity.
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Affiliation(s)
- A R White
- School of Biological Sciences, Biomedical Sciences Building, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK
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Mohan RM, Golding S, Heaton DA, Danson EJ, Paterson DJ. Targeting neuronal nitric oxide synthase with gene transfer to modulate cardiac autonomic function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 84:321-44. [PMID: 14769442 DOI: 10.1016/j.pbiomolbio.2003.11.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microdomains of neuronal nitric oxide synthase (nNOS) are spatially localised within both autonomic neurons innervating the heart and post-junctional myocytes. This review examines the use of gene transfer to investigate the role of nNOS in cardiac autonomic control. Furthermore, it explores techniques that may be used to improve upon gene delivery to the cardiac autonomic nervous system, potentially allowing more specific delivery of genes to the target neurons/myocytes. This may involve modification of the tropism of the adenoviral vector, or the use of alternative viral and non-viral gene delivery mechanisms to minimise potential immune responses in the host. Here we show that adenoviral vectors provide an efficient method of gene delivery to cardiac-neural tissue. Functionally, adenovirus-nNOS can increase cardiac vagal responsiveness by facilitating cholinergic neurotransmission and decrease beta-adrenergic excitability. Whether gene transfer remains the preferred strategy for targeting cardiac autonomic impairment will depend on site-specific promoters eliciting sustained gene expression that results in restoration of physiological function.
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Affiliation(s)
- R M Mohan
- University Laboratory of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK
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Miethke A, Feussner M, Planitzer G, Richter H, Gutsmann M, Gossrau R. Localization of NOS-1 in the sarcolemma region of a subpopulation of atrial cardiomyocytes including myoendocrine cells and NOS-3 in vascular and endocardial endothelial cells of the rat heart. Acta Histochem 2003; 105:43-55. [PMID: 12666987 DOI: 10.1078/0065-1281-00692] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cellular localization patterns of NOS isoforms 1 and 3 (nNOS and eNOS, respectively) in the mammalian heart under basal (non-stimulated) working conditions are still a matter of discussion. Therefore, this issue was reinvestigated in rats using RT-PCR, Western blotting, catalytic histochemistry, immunohistochemistry and image analysis. Tongue and extensor digitorum longus muscles served as positive controls for NOS-1 and NOS-3. RT-PCR revealed NOS-1 mRNA and NOS-3 mRNA in atria and ventricles. Western blotting showed NOS-1 protein in atria and NOS-3 protein in the walls of both heart chambers. Localization of the activity of urea-resistant (and therefore specific) NADPH diaphorase (NADPH-D) and NOS-1 immunohistochemistry showed that NOS-1 is present in the sarcolemma region of a subpopulation of atrial cardiomyocytes but not in working and impulse-conducting cardiomyocytes of atria and ventricles. Atrial natriuretic peptide (ANP) immunohistochemistry revealed that a minority of the NOS-1-expressing atrial cardiomyocytes are myoendocrine cells. eNOS immunostaining was present in endothelial cells of capillaries of the conducting and working myocardium and endocardial cells. Image analysis of the activity of urea-resistant NOS diaphorase showed that NOS-1 activity is lower in the sarcolemma region of atrial cardiomyocytes than in that of tongue and extensor digitorum longus myofibers. These data suggest that, in the non-stimulated rat heart. NOS-1 is expressed in a subpopulation of atrial cardiomyocytes including myoendocrine cells, and that NOS-3 is expressed in the vascular and endocardial endothelium.
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Affiliation(s)
- Alexander Miethke
- Department of Anatomy II, University Clinic Benjamin Franklin, Free University of Berlin, Berlin, Germany
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Abstract
The parasympathetic component of the autonomic nervous system plays an important role in the physiological regulation of cardiac function by exerting significant influence over the initiation as well as propagation of electrical impulses, in addition to being able to regulate contractile force. These effects are mediated in whole or in part through changes in ion channel activity that occur in response to activation of M(2) muscarinic cholinergic receptors following release of the neurotransmitter acetylcholine. The coupling of M(2) receptor activation to most changes in cardiac ion channel function can be explained by one of two general paradigms. The first involves direct G protein-dependent regulation of ion channel activity. The second involves indirect regulation of ion channel activity through modulation of cAMP-dependent responses. This review focuses on recent advances in our understanding of the mechanisms by which M(2) muscarinic receptor activation both inhibits and facilitates cAMP-dependent ion channel responses in the heart.
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Affiliation(s)
- Robert D Harvey
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, U.S.A.
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Iino K, Watanabe H, Saito T, Kibira S, Iijima T, Miura M. TNF-alpha rapidly antagonizes the beta-adrenergic responses of the chloride current in guinea-pig ventricular myocytes. Circ J 2003; 67:347-53. [PMID: 12655167 DOI: 10.1253/circj.67.347] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of this study was to test the hypothesis that tumor necrosis factor-alpha (TNF-alpha) rapidly antagonizes the beta-adrenergic responses of the chloride current and to clarify the intracellular mechanisms responsible for the anti-adrenergic action. The whole-cell patch-clamp technique was used to monitor the anti-adrenergic effects of TNF-alpha on the cAMP-dependent chloride current (I(Cl)) recorded from isolated guinea-pig ventricular myocytes. Ramp pulses (+/-120 mV; dv/dt = +/-0.4 V/s) were applied from the holding potential of -40 mV. TNF-alpha rapidly (<15 min) inhibited the isoproterenol (Iso, 0.1 micromol/L)-induced I(Cl) in a concentration-dependent manner (30-1,000 U/ml, IC (50) = 144 U/ml, n=30). The inhibitory action of TNF-alpha was also observed when I(Cl) had been previously stimulated by 1 micromol/L forskolin (n=5). Prior exposure of myocytes to 5 microg/ml pertussis toxin (PTX) hardly affected the anti-adrenergic action of TNF-alpha (n=4). However, when I(Cl) was induced by both 8-bromo-cAMP (100 micromol/L) and isobutylmethylxanthine (0.1 mmol/L), TNF-alpha (1,000 U/ml) failed to decrease I(Cl) amplitude (n=5). Prior exposure of myocytes to 5 mg/ml pertussis toxin (PTX) hardly affected the anti-adrenergic action of TNF-alpha (n=4). Furthermore, despite of the presence of nitro-L-arginine methyl ester (0.1 mmol/L), a nitric oxide synthase (NOS) inhibitor, TNF-alpha reversed the Iso-induced increase in I(Cl) (n=5). These results suggest that TNF-alpha rapidly antagonizes the beta-adrenergic responses of I(Cl) by reducing cAMP concentration. This anti-adrenergic action is mediated by neither the PTX-sensitive G proteins regulatory pathway nor constitutive NOS activation.
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Affiliation(s)
- Kenji Iino
- The 2nd Department of Internal Medicine, Akita University School of Medicine, Japan
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Rubio R, Ceballos G. Sole activation of three luminal adenosine receptor subtypes in different parts of coronary vasculature. Am J Physiol Heart Circ Physiol 2003; 284:H204-14. [PMID: 12388293 DOI: 10.1152/ajpheart.00068.2002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In isolated guinea pig hearts saline perfused at constant flow, adenosine A(1), A(2A), and A(3) (A(x)) agonists covalently bound to a large polymer (Pol; 2,000 kDa) were intracoronarily administered, and three effects were studied: dromotropic, vascular and inotropic. The rank order of potencies were the following: dromotropic (Pol-A(2A)Pol-A(1)>Pol-A(3)) and vascular and inotropic (Pol-A(2A)> or =Pol-A(1)Pol-A(3)), where the rank order of potency for Pol-A(x) depends on the part of the coronary vascular network involved; i.e., there is a vascular heterogeneity. The large size of Pol-A(x) prevents extravascular diffusion and causes it to act solely in the endothelial luminal surface. This implies their cardiac effects are due to endothelial mediators. Inhibition of nitric oxide (NO) and prostaglandin (PG) synthesis with N(G)-nitro-l-arginine methyl ester and indomethacin, respectively, show that the three cardiac effects of Pol-A(1) were mediated by NO and PG, whereas for Pol-A(2A) and Pol-A(3) the mediator was mainly NO but not PG. These results suggest that if Pol-A(x) activated the corresponding endothelial A(x)-receptor subtype, a different mediator would be produced.
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Affiliation(s)
- Rafael Rubio
- Departamento de Fisiologia, Faculdad de Medicina de la Universidad Autonoma de San Luis Potosi, Mexico.
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Massion PB, Balligand JL. Modulation of cardiac contraction, relaxation and rate by the endothelial nitric oxide synthase (eNOS): lessons from genetically modified mice. J Physiol 2003; 546:63-75. [PMID: 12509479 PMCID: PMC2342468 DOI: 10.1113/jphysiol.2002.025973] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The modulatory role of endothelial nitric oxide synthase (eNOS) on heart contraction, relaxation and rate is examined in light of recent studies using genetic deletion or overexpression in mice under specific conditions. Unstressed eNOS-/- hearts in basal conditions exhibit a normal inotropic and lusitropic function, with either decreased or unchanged heart rate. Under stimulation with catecholamines, eNOS-/- mice predominantly show a potentiation in their beta-adrenergic inotropic and lusitropic responsiveness. A similar phenotype is observed in beta 3-adrenoceptor deficient mice, pointing to a key role of this receptor subtype for eNOS coupling. The effect of eNOS on the muscarinic cholinergic modulation of cardiac function probably operates in conjunction with other NO-independent mechanisms, the persistence of which may explain the apparent dispensability of this isoform for the effect of acetylcholine in some eNOS-/- mouse strains. eNOS-/- hearts submitted to short term ischaemia-reperfusion exhibit variable alterations in systolic and diastolic function and infarct size, while those submitted to myocardial infarction present a worsened ventricular remodelling, increased 1 month mortality and loss of benefit from ACE inhibitor or angiotensin II type I receptor antagonist therapy. Although non-conditional eNOS gene deletion may engender phenotypic adaptations (e.g. ventricular hypertrophy resulting from chronic hypertension, or upregulation of the other NOS isoforms) potentially confounding the interpretation of comparative studies, the use of eNOS-/- mice has undoubtedly advanced (and will probably continue to improve) our understanding of the complex role of eNOS (in conjunction with the other NOSs) in the regulation of cardiac function. The challenge is now to confirm the emerging paradigms in human cardiac physiology and hopefully translate them into therapy.
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Affiliation(s)
- P B Massion
- Department of Medicine, Unit of Pharmacology and Therapeutics, Université Catholique de Louvain, Brussels, Belgium
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Bett GCL, Dai S, Campbell DL. Cholinergic modulation of the basal L-type calcium current in ferret right ventricular myocytes. J Physiol 2002; 542:107-17. [PMID: 12096055 PMCID: PMC2290407 DOI: 10.1113/jphysiol.2002.017335] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The effects of the cholinergic muscarinic agonist carbachol (CCh) on the basal L-type calcium current, I(Ca,L), in ferret right ventricular (RV) myocytes were studied using whole cell patch clamp. CCh produced two major effects : (i) in all myocytes, extracellular application of CCh inhibited I(Ca,L) in a reversible concentration-dependent manner; and (ii) in many (but not all) myocytes, upon washout CCh produced a significant transient stimulation of I(Ca,L) ('rebound stimulation'). Inhibitory effects could be observed at 1 x 10(-10) M CCh. The mean steady-state inhibitory concentration-response relationship was shallow and could be described with a single Hill equation (maximum inhibition = 34.5 %, IC50 = 4 x 10(-8) M, Hill coefficient n = 0.60). Steady-state inhibition (1 or 10 microM CCh) had no significant effect on I(Ca,L) selectivity or macroscopic (i) activation characteristics, (ii) inactivation kinetics, (iii) steady-state inactivation or (iv) kinetics of recovery from inactivation. Maximal inhibition of nitric oxide synthase (NOS) activity (preincubation of myocytes in 1 mM L-NMMA (N(G)-monomethyl-L-arginine) + 1 mM L-NNA (N(G)-nitro-L-arginine) for 2-3 h plus inclusion of 1 mM L-NMMA + 1 mM L-NNA in the patch pipette solution) produced no significant attenuation of the CCh-mediated inhibition of I(Ca,L). Protocols involving (i) the nitric oxide (NO) scavenger PTIO (2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide; 200 microM), (ii) imposition of a 'cGMP clamp' (100 microM 8-Bromo-cGMP), and (iii) inhibition of soluble guanylyl cyclase (ODQ (1H-[1,2,4,]oxadiazolo(4,3,-a)quinoxalin-1-one), 50 microM) all failed to attenuate CCh-mediated inhibition of I(ca,L). While CCh consistently inhibited basal I(Ca,L) in all RV myocytes studied, not all myocytes displayed rebound stimulation upon CCh washout. However, there was no difference between CCh-mediated inhibition of I(Ca,L) between these two RV myocyte types, and in myocytes displaying rebound stimulation neither ODQ nor 8-Bromo-cGMP (8-Br-cGMP) altered the effect. We conclude that NO production, activation of soluble guanylyl cyclase, or changes in intracellular cGMP levels are not obligatorily involved in muscarinic-mediated modulation of basal I(Ca,L) in ferret RV myocytes.
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Affiliation(s)
- Glenna C L Bett
- Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
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Planitzer G, Richter H, Gossrau R. The nitric oxide synthase-1 and nitric oxide synthase-3/nitric oxide signalling systems in the heart of wild type mice and mouse mutants. THE HISTOCHEMICAL JOURNAL 2002; 34:345-55. [PMID: 12769267 DOI: 10.1023/a:1023390811358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recently, we have shown that nitric oxide synthase-1 (NOS-1) and thus its product NO are present in the sarcolemma region of a subpopulation of atrial cardiomyocytes in the rat heart. In order to find out whether this newly discovered sarcolemma-associated NOS/NO system represents a general signalling mechanism in the murine rodent heart and whether its properties are comparable to those in skeletal muscle fibres, immunohistochemical and catalytic histochemical methods (including image analysis) were applied to the heart and extensor digitorum longus (EDL) and tongue muscles of wild type and mutant mice. In different strains of wild type mice and NOS-3 knockouts, urea-resistant (and therefore specific) NOS NADPH diaphorase histochemistry and NOS-1 immunohistochemistry revealed that NOS-1 activity and protein were present in the sarcolemma region of a subpopulation of atrial and ventricular working cardiomyocytes, but not in those of the impulse conducting system. Using image analysis, NOS-1 showed similar activities in the sarcolemma region of cardiomyocytes and in EDL type I myofibres. In mdx and NOS-1 knockout mice, NOS-1 was absent from the sarcolemma region of atrial and ventricular cardiomyocytes and of EDL and tongue muscle fibres, whereas NOS-1 was present in the hearts of NOS-3 knockouts. Atrial natriuretic peptide immunohistochemistry identified part of the atrial NOS-1-expressing cardiomyocytes as myoendocrine cells. In mdx mice as well as in NOS-1 - and NOS-3-deficient animals, the peptide was found in greater abundance than in wild type mice. These data suggest that NOS-1 is expressed in a subpopulation of working cardiomyocytes in the murine rodent heart, that the myoendocrine cells may be negatively modulated by NOS-1 - and NOS-3-produced NO, and that the anchoring mechanisms for NOS-1 in these cells (i.e. their confinement to the sarcolemma region) are comparable to those in skeletal muscle fibres.
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Affiliation(s)
- Gerit Planitzer
- Department of Anatomy II, University Clinic Benjamin Franklin, Free University of Berlin, Königin-Luise-Str. 15, D-14195 Berlin, Germany
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Abi-Gerges N, Szabo G, Otero AS, Fischmeister R, Méry PF. NO donors potentiate the beta-adrenergic stimulation of I(Ca,L) and the muscarinic activation of I(K,ACh) in rat cardiac myocytes. J Physiol 2002; 540:411-24. [PMID: 11956332 PMCID: PMC2290242 DOI: 10.1113/jphysiol.2001.012929] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The effects of nitric oxide (NO) donors on the L-type Ca(2+) current (I(Ca,L)) and the muscarinic activated K(+) current (I(K,ACh)) were studied in isolated rat cardiac myocytes. The nitrosothiol S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 1 pM-1 microM) strongly potentiated the stimulation of the I(Ca,L) elicited by subthreshold concentrations of isoprenaline (Iso, 0.1-0.5 nM) in ventricular myocytes. The effect of SNAP was mimicked by 2-(N,N-diethylamino)-diazenolate-2-oxide (DEANO, 1 pM-1 nM), a NONOate that spontaneously releases NO in a pH-controlled manner, and was blunted by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (100 microM), a NO trap. 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxaline-1-one (10 microM), a guanylyl cyclase inhibitor, did not alter the effect of SNAP. SNAP (1 pM-1 microM) did not modify the effect of L858051 (0.1-0.3 microM), a forskolin analogue that activates adenylyl cyclase, on I(Ca,L) and did not enhance the basal I(Ca,L) in the presence of rolipram (1 microM), a phosphodiesterase type 4 inhibitor. Superfusion with Rp-CPT-cAMPS (500 microM), or internal dialysis with cAMP-dependent protein kinase (cA-PK) inhibitory peptide (PKI; 20 microM), inhibitors of the cA-PK, blunted the effect of SNAP (1 nM and 1 microM) on the Iso-stimulated (1-100 pM) I(Ca,L). SNAP (1 nM and 1 microM) potentiated the threshold stimulation of I(Ca,L) elicited by internal GTP-gammaS (10 microM), a non-hydrolysable analogue of GTP. SNAP (1 pM-1 microM) and DEANO (1 microM) potentiated the stimulation of I(K,ACh) elicited by low concentrations of ACh (1-2 nM) in rat atrial myocytes. The threshold stimulation of I(K,ACh) elicited by internal 5'-guanylylimidodiphosphate (10 microM) was also potentiated by NO donors. SNAP (1 microM) did not modify I(K,ACh) reconstituted in human embryonic kidney 293 cells, in the absence or in the presence of ACh (1 or 10 nM). Taken together, these data suggest that NO is a cGMP-independent modulator of G-protein-coupled muscarinic and beta-adrenergic receptor actions on cardiac ion channels. Although this action of NO seemed to occur at the level of G proteins, it appeared to require a component distinct from receptors, G proteins or their effectors.
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Affiliation(s)
- Najah Abi-Gerges
- Laboratoire de Cardiologie Cellulaire et Moléculaire, INSERM U-446, Université Paris-Sud, Faculté de Pharmacie, F-92296 Châtenay-Malabry, France
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Nascimento JH, Sallé L, Hoebeke J, Argibay J, Peineau N. cGMP-mediated inhibition of cardiac L-type Ca(2+) current by a monoclonal antibody against the M(2) ACh receptor. Am J Physiol Cell Physiol 2001; 281:C1251-8. [PMID: 11546662 DOI: 10.1152/ajpcell.2001.281.4.c1251] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of a monoclonal antibody (B8E5) directed against the second extracellular loop of the muscarinic M(2) receptor were studied on the L-type Ca(2+) currents (I(Ca,L)) of guinea pig ventricular myocytes using the whole cell patch-clamp technique. Similar to carbachol, B8E5 reduced the isoproterenol (ISO)-stimulated I(Ca,L) but did not significantly affect basal I(Ca,L). Atropine blocked the inhibitory effect of B8E5. The electrophysiological parameters of ISO-stimulated I(Ca,L) were not modified in presence of B8E5. Inhibition of I(Ca,L) by B8E5 was still observed when intracellular cAMP was either enhanced by forskolin or maintained constant by using a hydrolysis-resistant cAMP analog (8-bromoadenosine 3',5'-cyclic monophosphate) or by applying the phosphodiesterase inhibitor IBMX. The effect of B8E5 was mimicked by 8-bromoguanosine 3',5'-cyclic monophosphate, a potent stimulator of cGMP-dependent protein kinase, and prevented by a selective inhibitor of nitric oxide-sensitive guanylyl cyclase [1H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one]. These results indicate that the antibody B8E5 inhibits the beta-adrenergic-stimulated I(Ca,L) through activation of the M(2) muscarinic receptor and further suggest that the antibody acts not via the classical pathway of decreasing intracellular cAMP, but rather by increasing cGMP.
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Affiliation(s)
- J H Nascimento
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21949-900 Rio de Janeiro, Brazil.
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Abstract
In the mammalian heart, cardiac function is under the control of the sympathetic and parasympathetic nervous system. All regions of the mammalian heart are innervated by parasympathetic (vagal) nerves, although the supraventricular tissues are more densely innervated than the ventricles. Vagal activation causes stimulation of cardiac muscarinic acetylcholine receptors (M-ChR) that modulate pacemaker activity via I(f) and I(K.ACh), atrioventricular conduction, and directly (in atrium) or indirectly (in ventricles) force of contraction. However, the functional response elicited by M-ChR-activation depends on species, age, anatomic structure investigated, and M-ChR-agonist concentration used. Among the five M-ChR-subtypes M(2)-ChR is the predominant isoform present in the mammalian heart, while in the coronary circulation M(3)-ChR have been identified. In addition, evidence for a possible existence of an additional, not M(2)-ChR in the heart has been presented. M-ChR are subject to regulation by G-protein-coupled-receptor kinase. Alterations of cardiac M(2)-ChR in age and various kinds of disease are discussed.
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Affiliation(s)
- S Dhein
- Institute of Pharmacology, University of Halle-Wittenberg, Germany.
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Gödecke A, Heinicke T, Kamkin A, Kiseleva I, Strasser RH, Decking UK, Stumpe T, Isenberg G, Schrader J. Inotropic response to beta-adrenergic receptor stimulation and anti-adrenergic effect of ACh in endothelial NO synthase-deficient mouse hearts. J Physiol 2001; 532:195-204. [PMID: 11368026 PMCID: PMC2278534 DOI: 10.1111/j.1469-7793.2001.0195g.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
1. The functional consequences of a lack of endothelial nitric oxide synthase (eNOS) on left ventricular force development and the anti-adrenergic effect of acetylcholine (ACh) were investigated in isolated hearts and cardiomyocytes from wild type (WT) and eNOS knockout (eNOS-/-) mice. 2.eNOS expression in cardiac myocytes accounted for 20 % of total cardiac eNOS (Western blot analysis). These results were confirmed by RT-PCR analysis. 3. In the unstimulated perfused heart, the left ventricular pressure (LVP) and maximal rate of left ventricular force development (dP/dtmax) of eNOS-/- hearts were not significantly different from those of WT hearts (LVP: 97 +/- 11 mmHg WT vs. 111 +/- 11 mmHg eNOS-/-; dP/dtmax: 3700 +/- 712 mmHg s(-1) WT vs. 4493 +/- 320 mmHg s)-1) eNOS-/-). 4. The dobutamine (10-300 nM)-induced increase in LVP was enhanced in eNOS-/- hearts. In contrast, L-type Ca2+ currents (ICa,L) in isolated cardiomyocytes of WT and eNOS-/- hearts showed no differences after beta-adrenergic stimulation. Dibutyryl-cGMP (50 microM) reduced basal ICa,L in WT cells to 72 +/- 12 % while eNOS-/- ICa,L was insensitive to the drug. The pre-stimulated ICa,L (30 nM isoproterenol) was attenuated by dibutyryl-cGMP in WT and eNOS-/- cells to the same extent. 5. The Ca2+ (1.5-4.5 mM)-induced increase in inotropy was not different between the two experimental groups and beta-adrenergic receptor density was increased by 50% in eNOS-/- hearts. 6. The contractile effects of dobutamine could be inhibited almost completely by ACh or adenosine. The extent of the anti-adrenergic effect of both compounds was identical in WT and eNOS-/- hearts. Measurement of ICa,L in isolated cardiac myocytes yielded similar results. 7. These data demonstrate that in the adult mouse (1) lack of eNOS is associated with increased cardiac contractile force in response to beta-adrenergic stimulation and with elevated -adrenergic receptor density, (2) the unaltered response of ICa,L in eNOS-/- cardiac myocytes to beta-adrenergic stimulation suggests that endothelium-derived NO is important in mediating the whole-organ effects and (3) eNOS is unimportant for the anti-adrenergic effect of ACh and adenosine.
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Affiliation(s)
- A Gödecke
- Institut für Herz- und Kreislauf physiologie, Heinrich-Heine-Universität Düsseldorf, Germany
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Kumar A, Krieger A, Symeoneides S, Kumar A, Parrillo JE. Myocardial dysfunction in septic shock: Part II. Role of cytokines and nitric oxide. J Cardiothorac Vasc Anesth 2001; 15:485-511. [PMID: 11505357 DOI: 10.1053/jcan.2001.25003] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- A Kumar
- Division of Cardiovascular Diseases and Critical Care Medicine, Department of Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA
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Chen F, Spicher K, Jiang M, Birnbaumer L, Wetzel GT. Lack of muscarinic regulation of Ca(2+) channels in G(i2)alpha gene knockout mouse hearts. Am J Physiol Heart Circ Physiol 2001; 280:H1989-95. [PMID: 11299198 DOI: 10.1152/ajpheart.2001.280.5.h1989] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of the present study was to examine the role of G(i2)alpha in Ca(2+) channel regulation using G(i2)alpha gene knockout mouse ventricular myocytes. The whole cell voltage-clamp technique was used to study the effects of the muscarinic agonist carbachol (CCh) and the beta-adrenergic agonist isoproterenol (Iso) on cardiac L-type Ca(2+) currents in both 129Sv wild-type (WT) and G(i2)alpha gene knockout (G(i2)alpha-/-) mice. Perfusion with CCh significantly inhibited the Ca(2+) current in WT cells, and this effect was reversed by adding atropine to the CCh-containing solution. In contrast, CCh did not affect Ca(2+) currents in G(i2)alpha-/- ventricular myocytes. Addition of CCh to Iso-containing solutions attenuated the Iso-stimulated Ca(2+) current in WT cardiomyocytes but not in G(i2)alpha-/- cells. These findings demonstrate that, whereas the Iso-G(s)alpha signal pathway is intact in G(i2)alpha gene knockout mouse hearts, these cells lack the inhibitory regulation of Ca(2+) channels by CCh. Therefore, G(i2)alpha is necessary for the muscarinic regulation of Ca(2+) channels in the mouse heart. Further studies are needed to delineate the possible interaction of G(i) and other cell signaling proteins and to clarify the level of interaction of G protein-coupled regulation of L-type Ca(2+) current in the heart.
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Affiliation(s)
- F Chen
- Department of Pediatrics, University of California School of Medicine, Los Angeles, California 90095, USA.
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Nahavandi A, Dehpour AR, Mani AR, Homayounfar H, Abdoli A, Abdolhoseini MR. The role of nitric oxide in bradycardia of rats with obstructive cholestasis. Eur J Pharmacol 2001; 411:135-141. [PMID: 11137868 DOI: 10.1016/s0014-2999(00)00773-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nitric oxide (NO) has an important role in controlling heart rate and contributes to the cholinergic antagonism of the positive chronotropic response to adrenergic stimulation. Based on evidence of NO overproduction in cholestasis and also on the existence of bradycardia in cholestatic subjects, this study aimed to evaluate the chronotropic effect of epinephrine in isolated atria of cholestatic rats and determine whether alterations in epinephrine-induced chronotropic responses of cholestatic rats are corrected after systemic inhibition of NO synthase (NOS) with N(G)-nitro-L-arginine (L-NNA). Male Sprague-Dawley rats were used. Cholestasis was induced by surgical ligation of the bile duct under general anesthesia and sham-operated animals were considered as control. The animals were divided into three groups, which received either L-arginine (200 mg/kg/day), L-NNA (10 mg/kg/day) or saline. One week after the operation, a lead II ECG was recorded from the animals, then spontaneously beating atria were isolated and chronotropic responses to epinephrine were evaluated in a standard oxygenated organ bath. The results showed that plasma gamma-glutamyl transpeptidase and alanine aminotransferase activity was increased by bile-duct ligation, and that L-aginine treatment partially, but significantly, prevented the elevation of these markers of liver damage. The results showed that heart rate of cholestatic animals was significantly less than that of sham-operated control rats in vivo and this bradycardia was corrected with daily administration of L-NNA. The basal spontaneous beating rate of atria in cholestatic animals was not significantly different from that of sham-operated rats in vitro. Meanwhile, cholestasis induced a significant decrease in chronotropic effect of epinephrine. These effects were corrected by daily administration of L-NNA. Surprisingly L-arginine was as effective as L-NNA and increased the chronotropic effect of epinephrine in cholestatic rats but not in sham-operated animals. Systemic NOS inhibition corrected the decreased chronotropic response to adrenergic stimulation in cholestatic rats, and suggests an important role for NO in the pathophysiology of heart rate complications in cholestatic subjects. The opposite effect of chronic L-arginine administration in cholestasis and in control rats could be explained theoretically by an amelioration of cholestasis-induced liver damage by chronic L-arginine administration in bile duct-ligated rats.
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Affiliation(s)
- A Nahavandi
- Department of Physiology, Iran University of Medical Sciences, P.O. Box 14155-6183, Tehran, Iran.
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Lecour S, Maupoil V, Zeller M, Laubriet A, Briot T, Rochette L. Levels of nitric oxide in the heart after experimental myocardial ischemia. J Cardiovasc Pharmacol 2001; 37:55-63. [PMID: 11152374 DOI: 10.1097/00005344-200101000-00007] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effect of myocardial ischemia on nitric oxide (NO) production is controversial in part because of indirect NO quantification. In the present study, direct quantification of NO was investigated in an in vivo rat model of myocardial ischemia (MI). A NO spin-trapping technique using electron spin resonance (ESR) spectroscopy was used to study NO production in the ischemic and in the nonischemic area of the rat heart 2, 8, or 24 h after left main coronary artery ligation. The method was based on the trapping of NO by a metal-chelator complex consisting of N-methyl-D-glucamine-dithiocarbamate (MGD) and Fe(II) to form a stable NO-FeMGD complex that gives rise to a characteristic triplet ESR spectrum. This metal-chelator complex was administered half an hour before sacrifice of the rats. A large and time-dependent increase of the ESR signal corresponding to the NO-FeMGD complex was observed 8 h (11.6 +/- 0.9 arbitrary units [AU]) and 24 h (29.7 +/- 2.9 AU) in the ischemic area after MI. On the contrary, no ESR triplet was observed in the nonischemic region of the heart and in sham-operated rats. NO blood derivative levels (nitrosylhemoglobin and plasma nitrites and nitrates) were unchanged compared with sham-operated rats. Previous administration of aminoguanidine, a NO synthase inhibitor, in animals subjected to a 24-h ischemia resulted in a complete abolition in the NO-FeMGD spectrum in the ischemic area. These findings directly demonstrated an increase of the NO-FeMGD levels during in vivo myocardial ischemia that appeared to be specifically localized in the ischemic area.
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Affiliation(s)
- S Lecour
- Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimrentales, Facultés de Médecine et Pharmacie, Dijon, France.
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Sasaki S, Daitoku K, Iwasa A, Motomura S. NO is involved in MCh-induced accentuated antagonism via type II PDE in the canine blood-perfused SA node. Am J Physiol Heart Circ Physiol 2000; 279:H2509-18. [PMID: 11045989 DOI: 10.1152/ajpheart.2000.279.5.h2509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The possible role of type II (cGMP-stimulated cAMP hydrolysis) phosphodiesterase (PDE) in the accentuated antagonism of muscarinic effects on heart rate during beta-stimulation via endogenous nitric oxide (NO) was evaluated. The canine isolated sinoatrial node preparation was cross circulated with arterial blood of a support dog. The sinoatrial rate of the preparation was 96 +/- 5 beats/min (n = 16) at control. Methacholine (MCh; 0.01-1 microg) injected into the right coronary artery in a bolus fashion caused dose-dependent decreases in sinoatrial rate. Under an intra-arterial infusion of isoproterenol (1 microM), resulting in approximately 50% increase in sinoatrial rate, MCh-induced decreases were markedly augmented from -18 +/- 3% to -44 +/- 4% at 0.3 mg of MCh. When N(G)-nitro-L-arginine methyl ester (100 microM) or N(G)-monomethyl-L-arginine (100 microM) were continuously infused, the augmented MCh-induced decreases in sinoatrial rate were significantly suppressed (-29 +/- 3% or -25 +/- 3%, respectively, P < 0.01). Pretreatment with either 3-isobutyl-1-methylxanthine (IBMX; 20 microM), a non-selective PDE inhibitor, or amrinone (20 microM), a selective type III (cGMP inhibited cAMP hydrolysis) PDE inhibitor, doubled the isoproterenol-induced increase in the sinoatrial rate. However, the augmented MCh-induced decreases in sinoatrial rate were significantly depressed by IBMX (from -23 +/- 5% to -14 +/- 1%, P < 0.01) but not by amrinone (to -20 +/- 3%). These results suggest that MCh-induced accentuated antagonism in the sinoatrial node pacemaker activity can be modulated by endogenous NO via an activation of the type II cyclic GMP-stimulated cAMP PDE.
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Affiliation(s)
- S Sasaki
- Department of Pharmacology, Hirosaki University School of Medicine, Hirosaki 036-8562, Japan
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Gauthier C, Leblais V, Moniotte S, Langin D, Balligand JL. The negative inotropic action of catecholamines: Role of β3-adrenoceptors. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y00-045] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is now evidence for the involvement of four β-adrenoceptor populations in the regulation of cardiac function by catecholamines. β1- and β2-adrenoceptor stimulation classically produces an increase in contractility. A fourth β-adrenoceptor, as yet uncloned and designated provisionally as a β4-adrenoceptor, also mediates a positive inotropic effect. β3-adrenoceptors, which had been cloned at the end of the eighties, has been extensively studied as a potential target for antiobesity and antidiabetic drugs. Its characterization in the heart has opened new fields of investigations for the understanding of the cardiac adrenergic regulation. This review describes the cardiac electrical and mechanical effects induced by β3-adrenoceptor stimulation in different species (including human), as well as the signaling pathway. It also analyzes the role of these receptors in the abnormal responsiveness of catecholamines in heart failure.Key words: beta-adrenoceptor, heart, contractility, signaling pathway, heart failure.
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Zima A, Martynyuk AE, Seubert CN, Morey TE, Sumners C, Cucchiara RF, Dennis DM. Antagonism of the positive dromotropic effect of isoproterenol by adenosine: role of nitric oxide, cGMP-dependent cAMP-phosphodiesterase and protein kinase G. J Mol Cell Cardiol 2000; 32:1609-19. [PMID: 10966824 DOI: 10.1006/jmcc.2000.1196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that nitric oxide (NO) plays an important role in mediating the anti-adrenergic effect of adenosine on atrioventricular (AV) nodal conduction. In guinea-pig hearts instrumented for measurement of AV nodal conduction time (atrium-to-His bundle, A-H, interval), the NO synthase (NOS) inhibitor, l-NMMA (100 microm), reversibly inhibited 80% (P=0.009, n=6) of adenosine's anti-adrenergic action on the positive dromotropic effect of isoproterenol (0.01 microm). In parallel studies carried out in rabbit AV nodal myocytes, intracellular mechanisms whereby NO mediates the inhibitory effect of adenosine on isoproterenol-induced A-H interval shortening were studied. Adenosine (3 microm) inhibited isoproterenol-stimulated (0.1 microm) I(Ca,L)(beta -I(Ca,L)) by 46+/-6% (P<0.001, n=17). Consistent with isolated heart data, the NOS inhibitors, l -NMMA (100 microm) and L-NNA (500 microm) attenuated the effect of adenosine on beta -I(Ca,L)by 69+/-8% (P<0.001, n=16) and 69+/-7% (P<0.001, n=10), respectively. An inhibitor of NO-stimulated guanylyl cyclase LY83538 (40 microm) reduced the inhibitory effect of adenosine on beta -I(Ca,L)by 97+/-6% (P=0.004, n=15). Similarly, the non-specific inhibitor of cAMP-phosphodiesterases IBMX (50 microm) decreased the anti-adrenergic effect of adenosine by 60% (P=0.02, n=6), whereas the extracellular application of the non-hydrolyzeable cAMP analog 8-Br-cAMP (500 microm) prevented this action of adenosine. Activation of cGMP-dependent protein kinase (PKG) by CPT-cGMP (300 microm) diminished beta -I(Ca,L), but to a significantly smaller degree (16+/-4%, P=0.025, n=12) than that caused by adenosine. NO mediates the anti-adrenergic effect of adenosine on AV nodal conduction by a mechanism predominately involving activation of cGMP-dependent cAMP-phosphodiesterase and to a lesser extent activation of PKG.
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Affiliation(s)
- A Zima
- Department of Anesthesiology, University of Florida, Gainesville, FL, 32610, USA
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Korshunov VA, Murashev AN, Ivashev MN, Dugin SF, Medvedev OS. Hemodynamic effects of tetrindol in alert normotensive mice and rats after blockade of nitric oxide synthesis. Bull Exp Biol Med 2000; 130:777-9. [PMID: 11177242 DOI: 10.1007/bf02766093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2000] [Indexed: 10/22/2022]
Abstract
Single intravenous injection of antidepressant tetrindol (1 and 10 mg/kg), a reversible monoamine oxidase A inhibitor, dose-dependently decreased heart rate and mean arterial pressure (in a concentration of 10 mg/kg) in alert NMRI mice and Sprague-Dawley rats. Nitric oxide synthase blockade with L-NAME attenuated tetrindol-induced bradycardia in rats and completely abolished this effect in mice.
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Affiliation(s)
- V A Korshunov
- Group of Pharmacology, Branch of the Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Moscow region
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