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Targosova K, Kucera M, Fazekas T, Kilianova Z, Stankovicova T, Hrabovska A. α7 nicotinic receptors play a role in regulation of cardiac hemodynamics. J Neurochem 2024; 168:414-427. [PMID: 37017608 DOI: 10.1111/jnc.15821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/06/2023]
Abstract
The α7 nicotinic receptors (NR) have been confirmed in the heart but their role in cardiac functions has been contradictory. To address these contradictory findings, we analyzed cardiac functions in α7 NR knockout mice (α7-/-) in vivo and ex vivo in isolated hearts. A standard limb leads electrocardiogram was used, and the pressure curves were recorded in vivo, in Arteria carotis and in the left ventricle, or ex vivo, in the left ventricle of the spontaneously beating isolated hearts perfused following Langedorff's method. Experiments were performed under basic conditions, hypercholinergic conditions, and adrenergic stress. The relative expression levels of α and β NR subunits, muscarinic receptors, β1 adrenergic receptors, and acetylcholine life cycle markers were determined using RT-qPCR. Our results revealed a prolonged QT interval in α7-/- mice. All in vivo hemodynamic parameters were preserved under all studied conditions. The only difference in ex vivo heart rate between genotypes was the loss of bradycardia in prolonged incubation of isoproterenol-pretreated hearts with high doses of acetylcholine. In contrast, left ventricular systolic pressure was lower under basal conditions and showed a significantly higher increase during adrenergic stimulation. No changes in mRNA expression were observed. In conclusion, α7 NR has no major effect on heart rate, except when stressed hearts are exposed to a prolonged hypercholinergic state, suggesting a role in acetylcholine spillover control. In the absence of extracardiac regulatory mechanisms, left ventricular systolic impairment is revealed.
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Affiliation(s)
- Katarina Targosova
- Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University Bratislava, Bratislava, Slovakia
| | - Matej Kucera
- Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University Bratislava, Bratislava, Slovakia
| | - Tomas Fazekas
- Faculty of Pharmacy, Department of Physical Chemistry of Drugs, Comenius University Bratislava, Bratislava, Slovakia
| | - Zuzana Kilianova
- Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University Bratislava, Bratislava, Slovakia
| | - Tatiana Stankovicova
- Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University Bratislava, Bratislava, Slovakia
| | - Anna Hrabovska
- Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University Bratislava, Bratislava, Slovakia
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Gergs U, Wackerhagen S, Fuhrmann T, Schäfer I, Neumann J. Further investigations on the influence of protein phosphatases on the signaling of muscarinic receptors in the atria of mouse hearts. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-02973-4. [PMID: 38308688 DOI: 10.1007/s00210-024-02973-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/21/2024] [Indexed: 02/05/2024]
Abstract
The vagal regulation of cardiac function involves acetylcholine (ACh) receptor activation followed by negative chronotropic and negative as well as positive inotropic effects. The resulting signaling pathways may include Gi/o protein-coupled reduction in adenylyl cyclase (AC) activity, direct Gi/o protein-coupled activation of ACh-activated potassium current (IKACh), inhibition of L-type calcium ion channels, and/or the activation of protein phosphatases. Here, we studied the role of the protein phosphatases 1 (PP1) and 2A (PP2A) for muscarinic receptor signaling in isolated atrial preparations of transgenic mice with cardiomyocyte-specific overexpression of either the catalytic subunit of PP2A (PP2A-TG) or the inhibitor-2 (I2) of PP1 (I2-TG) or in double transgenic mice overexpressing both PP2A and I2 (DT). In mouse left atrial preparations, carbachol (CCh), cumulatively applied (1 nM-10 µM), exerted at low concentrations a negative inotropic effect followed by a positive inotropic effect at higher concentrations. This biphasic effect was noted with CCh alone as well as when CCh was added after β-adrenergic pre-stimulation with isoprenaline (1 µM). Whereas the response to stimulation of β-adrenoceptors or adenosine receptors (used as controls) was changed in PP2A-TG, the response to CCh was unaffected in atrial preparations from all transgenic models studied here. Therefore, the present data tentatively indicate that neither PP2A nor PP1, but possibly other protein phosphatases, is involved in the muscarinic receptor-induced inotropic and chronotropic effects in the mouse heart.
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Affiliation(s)
- Ulrich Gergs
- Institut Für Pharmakologie Und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Magdeburger Str. 4, 06112, Halle, Germany.
| | - Silke Wackerhagen
- Institut Für Pharmakologie Und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Magdeburger Str. 4, 06112, Halle, Germany
| | - Tobias Fuhrmann
- Institut Für Pharmakologie Und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Magdeburger Str. 4, 06112, Halle, Germany
| | - Inka Schäfer
- Institut Für Pharmakologie Und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Magdeburger Str. 4, 06112, Halle, Germany
| | - Joachim Neumann
- Institut Für Pharmakologie Und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Magdeburger Str. 4, 06112, Halle, Germany
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Hohendanner F, Prabhu A, Wilck N, Stangl V, Pieske B, Stangl K, Althoff TF. G q-Mediated Arrhythmogenic Signaling Promotes Atrial Fibrillation. Biomedicines 2023; 11:biomedicines11020526. [PMID: 36831062 PMCID: PMC9953645 DOI: 10.3390/biomedicines11020526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is promoted by various stimuli like angiotensin II, endothelin-1, epinephrine/norepinephrine, vagal activation, or mechanical stress, all of which activate receptors coupled to G-proteins of the Gαq/Gα11-family (Gq). Besides pro-fibrotic and pro-inflammatory effects, Gq-mediated signaling induces inositol trisphosphate receptor (IP3R)-mediated intracellular Ca2+ mobilization related to delayed after-depolarisations and AF. However, direct evidence of arrhythmogenic Gq-mediated signaling is absent. METHODS AND RESULTS To define the role of Gq in AF, transgenic mice with tamoxifen-inducible, cardiomyocyte-specific Gαq/Gα11-deficiency (Gq-KO) were created and exposed to intracardiac electrophysiological studies. Baseline electrophysiological properties, including heart rate, sinus node recovery time, and atrial as well as AV nodal effective refractory periods, were comparable in Gq-KO and control mice. However, inducibility and mean duration of AF episodes were significantly reduced in Gq-KO mice-both before and after vagal stimulation. To explore underlying mechanisms, left atrial cardiomyocytes were isolated from Gq-KO and control mice and electrically stimulated to study Ca2+-mobilization during excitation-contraction coupling using confocal microscopy. Spontaneous arrhythmogenic Ca2+ waves and sarcoplasmic reticulum content-corrected Ca2+ sparks were less frequent in Gq-KO mice. Interestingly, nuclear but not cytosolic Ca2+ transient amplitudes were significantly decreased in Gq-KO mice. CONCLUSION Gq-signaling promotes arrhythmogenic atrial Ca2+-release and AF in mice. Targeting this pathway, ideally using Gq-selective, biased receptor ligands, may be a promising approach for the treatment and prevention of AF. Importantly, the atrial-specific expression of the Gq-effector IP3R confers atrial selectivity mitigating the risk of life-threatening ventricular pro-arrhythmic effects.
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Affiliation(s)
- Felix Hohendanner
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Ashok Prabhu
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Nicola Wilck
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Experimental and Clinical Research Center (ECRC), a Cooperation of Charité–Universitätsmedizin Berlin and Max Delbruck Center for Molecular Medicine (MDC), 13125 Berlin, Germany
- Department of Nephrology and Medical Intensive Care Medicine, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Verena Stangl
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Burkert Pieske
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Karl Stangl
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Till F. Althoff
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
- Arrhythmia Section, Cardiovascular Institute (ICCV), Hospital Clínic, Universitat de Barcelona, C/Villarroel N° 170, 08036 Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
- Correspondence: ; Tel.: +34-93-2275551; Fax: +34-93-4513045
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Lyu Q, Gong S, Lees JG, Yin J, Yap LW, Kong AM, Shi Q, Fu R, Zhu Q, Dyer A, Dyson JM, Lim SY, Cheng W. A soft and ultrasensitive force sensing diaphragm for probing cardiac organoids instantaneously and wirelessly. Nat Commun 2022; 13:7259. [PMID: 36433978 PMCID: PMC9700778 DOI: 10.1038/s41467-022-34860-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 11/09/2022] [Indexed: 11/27/2022] Open
Abstract
Time-lapse mechanical properties of stem cell derived cardiac organoids are important biological cues for understanding contraction dynamics of human heart tissues, cardiovascular functions and diseases. However, it remains difficult to directly, instantaneously and accurately characterize such mechanical properties in real-time and in situ because cardiac organoids are topologically complex, three-dimensional soft tissues suspended in biological media, which creates a mismatch in mechanics and topology with state-of-the-art force sensors that are typically rigid, planar and bulky. Here, we present a soft resistive force-sensing diaphragm based on ultrasensitive resistive nanocracked platinum film, which can be integrated into an all-soft culture well via an oxygen plasma-enabled bonding process. We show that a reliable organoid-diaphragm contact can be established by an 'Atomic Force Microscope-like' engaging process. This allows for instantaneous detection of the organoids' minute contractile forces and beating patterns during electrical stimulation, resuscitation, drug dosing, tissue culture, and disease modelling.
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Affiliation(s)
- Quanxia Lyu
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Shu Gong
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Jarmon G. Lees
- grid.1073.50000 0004 0626 201XO’Brien Institute Department, St. Vincent’s Institute of Medical Research, Fitzroy, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medicine and Surgery, University of Melbourne, Melbourne, VIC Australia
| | - Jialiang Yin
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Lim Wei Yap
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Anne M. Kong
- grid.1073.50000 0004 0626 201XO’Brien Institute Department, St. Vincent’s Institute of Medical Research, Fitzroy, VIC Australia
| | - Qianqian Shi
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Runfang Fu
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia
| | - Qiang Zhu
- grid.410660.5The Melbourne Centre for Nanofabrication, Clayton, VIC 3800 Australia
| | - Ash Dyer
- grid.410660.5The Melbourne Centre for Nanofabrication, Clayton, VIC 3800 Australia
| | - Jennifer M. Dyson
- Department of Biochemistry & Molecular Biology, Biomedicine Discovery Institute, Clayton, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Faculty of Engineering, Monash Institute of Medical Engineering (MIME), Monash University, Clayton, VIC 3800 Australia
| | - Shiang Y. Lim
- grid.1073.50000 0004 0626 201XO’Brien Institute Department, St. Vincent’s Institute of Medical Research, Fitzroy, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medicine and Surgery, University of Melbourne, Melbourne, VIC Australia ,grid.1002.30000 0004 1936 7857Drug Discovery Biology, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia ,grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore
| | - Wenlong Cheng
- grid.1002.30000 0004 1936 7857Department of Chemical & Biological Engineering, Monash University, Clayton, VIC 3800 Australia ,grid.410660.5The Melbourne Centre for Nanofabrication, Clayton, VIC 3800 Australia
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RGS3L allows for an M 2 muscarinic receptor-mediated RhoA-dependent inotropy in cardiomyocytes. Basic Res Cardiol 2022; 117:8. [PMID: 35230541 PMCID: PMC8888479 DOI: 10.1007/s00395-022-00915-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 01/31/2023]
Abstract
The role and outcome of the muscarinic M2 acetylcholine receptor (M2R) signaling in healthy and diseased cardiomyocytes is still a matter of debate. Here, we report that the long isoform of the regulator of G protein signaling 3 (RGS3L) functions as a switch in the muscarinic signaling, most likely of the M2R, in primary cardiomyocytes. High levels of RGS3L, as found in heart failure, redirect the Gi-mediated Rac1 activation into a Gi-mediated RhoA/ROCK activation. Functionally, this switch resulted in a reduced production of reactive oxygen species (- 50%) in cardiomyocytes and an inotropic response (+ 18%) in transduced engineered heart tissues. Importantly, we could show that an adeno-associated virus 9-mediated overexpression of RGS3L in rats in vivo, increased the contractility of ventricular strips by maximally about twofold. Mechanistically, we demonstrate that this switch is mediated by a complex formation of RGS3L with the GTPase-activating protein p190RhoGAP, which balances the activity of RhoA and Rac1 by altering its substrate preference in cardiomyocytes. Enhancement of this complex formation could open new possibilities in the regulation of the contractility of the diseased heart.
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Targosova K, Kucera M, Kilianova Z, Slobodova L, Szmicsekova K, Hrabovska A. Cardiac nicotinic receptors show β-subunit-dependent compensatory changes. Am J Physiol Heart Circ Physiol 2021; 320:H1975-H1984. [PMID: 33769917 DOI: 10.1152/ajpheart.00995.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nicotinic receptors (NRs) play an important role in the cholinergic regulation of heart functions, and converging evidence suggests a diverse repertoire of NR subunits in the heart. A recent hypothesis about the plasticity of β NR subunits suggests that β2-subunits and β4-subunits may substitute for each other. In our study, we assessed the hypothetical β-subunit interchangeability in the heart at the level of mRNA. Using two mutant mice strains lacking β2 or β4 NR subunits, we examined the relative expression of NR subunits and other key cholinergic molecules. We investigated the physiology of isolated hearts perfused by Langendorff's method at basal conditions and after cholinergic and/or adrenergic stimulation. Lack of β2 NR subunit was accompanied with decreased relative expression of β4-subunits and α3-subunits. No other cholinergic changes were observed at the level of mRNA, except for increased M3 and decreased M4 muscarinic receptors. Isolated hearts lacking β2 NR subunit showed different dynamics in heart rate response to indirect cholinergic stimulation. In hearts lacking β4 NR subunit, increased levels of β2-subunits were observed together with decreased mRNA for acetylcholine-synthetizing enzyme and M1 and M4 muscarinic receptors. Changes in the expression levels in β4-/- hearts were associated with increased basal heart rate and impaired response to a high dose of acetylcholine upon adrenergic stimulation. In support of the proposed plasticity of cardiac NRs, our results confirmed subunit-dependent compensatory changes to missing cardiac NRs subunits with consequences on isolated heart physiology.NEW & NOTEWORTHY In the present study, we observed an increase in mRNA levels of the β2 NR subunit in β4-/- hearts but not vice versa, thus supporting the hypothesis of β NR subunit plasticity that depends on the specific type of missing β-subunit. This was accompanied with specific cholinergic adaptations. Nevertheless, isolated hearts of β4-/- mice showed increased basal heart rate and a higher sensitivity to a high dose of acetylcholine upon adrenergic stimulation.
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Affiliation(s)
- Katarina Targosova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Matej Kucera
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Zuzana Kilianova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia.,Department of Pharmacology, Slovak Medical University in Bratislava, Bratislava, Slovakia
| | - Lubica Slobodova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia.,Department of Pharmacology, Slovak Medical University in Bratislava, Bratislava, Slovakia
| | - Kristina Szmicsekova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Anna Hrabovska
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia.,Department of Pharmacology, Slovak Medical University in Bratislava, Bratislava, Slovakia.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
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Tanahashi Y, Katsurada T, Inasaki N, Uchiyama M, Sakamoto T, Yamamoto M, Matsuyama H, Komori S, Unno T. Further characterization of the synergistic activation mechanism of cationic channels by M 2 and M 3 muscarinic receptors in mouse intestinal smooth muscle cells. Am J Physiol Cell Physiol 2019; 318:C514-C523. [PMID: 31875697 DOI: 10.1152/ajpcell.00277.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mouse ileal myocytes, muscarinic receptor-mediated cationic current (mIcat) occurs mainly through synergism of M2 and M3 subtypes involving Gi/o-type GTP-binding proteins and phospholipase C (PLC). We have further studied the M2/M3 synergistic pathway. Carbachol-induced mIcat was markedly depressed by YM-254890, a Gq/11 protein inhibitor. However, the mIcat was unaffected by heparin, calphostin C, or chelerythrine, suggesting that mIcat activation does not involve signaling molecules downstream of phosphatidylinositol 4,5-bisphosphate (PIP2) breakdown. M2-knockout (KO) mice displayed a reduced mIcat (~10% of wild-type mIcat) because of the lack of M2-Gi/o signaling. The impaired mIcat was insensitive to neuropeptide Y possessing a Gi/o-stimulating activity. M3-KO mice also displayed a reduced mIcat (~6% of wild-type mIcat) because of the lack of M3-Gq/11 signaling, and the mIcat was insensitive to prostaglandin F2α possessing a Gq/11-stimulating activity. These results suggest the importance of Gq/11/PLC-hydrolyzed PIP2 breakdown itself in mIcat activation and also support the idea that the M2/M3 synergistic pathway represents a signaling complex consisting of M2-Gi/o and M3-Gq/11-PLC systems in which both G proteins are special for this pathway but not general in receptor coupling.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Taisuke Katsurada
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Noriko Inasaki
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Mai Uchiyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Takashi Sakamoto
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Masayuki Yamamoto
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Hayato Matsuyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Seiichi Komori
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Toshihiro Unno
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
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Acute restraint stress modifies the heart rate biorhythm in the poststress period. Sci Rep 2019; 9:1794. [PMID: 30742021 PMCID: PMC6370754 DOI: 10.1038/s41598-019-38523-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 12/28/2018] [Indexed: 11/13/2022] Open
Abstract
We studied the changes in the heart and the activity biorhythms in mice exposed to acute (one 120-minute session) and repeated (7 two-hour sessions) restraint stress in 129J1/CF1 mice (WT) and in mice without M2 muscarinic receptors (M2KO) during the prestress period, during stress (STR) and for five days after the last stress session (POST). There were changes in the mesor (a midline based on the distribution of values across the circadian cycles; decreased in M2KO by 6% over all POST), day means (inactive period of diurnal rhythm in mice; higher in M2KO and further increased on STR and on the second to the fifth POST) and night means (active period; lower by 13% in M2KO and remained decreased in STR and in POST). The total area under the curve was decreased both in the WT and M2KO on STR and in all POST. Repeated stress caused changes over all days of STR, but the initial values were restored in POST. The average night values were decreased, and the day means were increased by 16% over all STR in M2KO. The day means decreased by 14% in the 4 POST in WT. The activity biorhythm parameters were almost unchanged. We show here that stress can specifically affect heart biorhythm in M2KO mice, especially when the stress is acute. This implies the role of M2 muscarinic receptor in stress response.
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Zhang S, Takahashi R, Yamashita N, Teraoka H, Kitazawa T. Αlpha 1B-adrenoceptor-mediated positive inotropic and positive chronotropic actions in the mouse atrium. Eur J Pharmacol 2018; 839:82-88. [PMID: 30172786 DOI: 10.1016/j.ejphar.2018.08.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 08/21/2018] [Accepted: 08/29/2018] [Indexed: 11/15/2022]
Abstract
Modulation of cardiac contractility by α-adrenoceptor is well known in several mammals. Mice are useful experimental animals, but α-adrenoceptor-mediated responses have been examined only in the ventricles. To determine function of α-adrenoceptors in the atrium, effects of α-adrenoceptor agonists on spontaneous contraction and electrical-field stimulation (EFS)-induced contraction were examined. In addition, expression of α1A, α1B, α1D and β1-adrenoceptor mRNAs were examined. In the right atrium, noradrenaline and phenylephrine caused positive inotropic and positive chronotropic actions. However, methoxamine, clonidine and xylazine caused positive inotropic actions, but contractile frequency was decreased at high concentrations. Phenylephrine-induced positive inotropic and chronotropic actions were partially decreased by propranolol, and both actions remained in the presence of propranolol were inhibited by phentolamine or prazosin. A low concentration of silodosin (<100 nM) did not but a high concentration (1 μM) decreased the phenylephrine-induced chronotropic actions. Negative chronotropic actions of clonidine and xylazine were insensitive to propranolol and phentolamine. The EFS-induced contraction of the left atrium was potentiated by noradrenaline, phenylephrine and methoxamine but was not changed by clonidine or xylazine. Propranolol partially decreased the actions of phenylephrine, and prazosin caused additional inhibition. Expression of β1-, α1A-, α1B- and α1D-adrenoceptor mRNAs was found in the atrium, and the expression level of β1-adrenoceptor was the highest. Of α1-adrenoceptors, the expression level of α1B was higher than that of α1A and α1D. In conclusion, α1B-adrenoceptors are expressed in the mouse atrium and mediate both positive chronotropic and inotropic actions. In contrast, the α2-adrenoceptor is not functional in the isolated atrium.
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Affiliation(s)
- Shuangyi Zhang
- Veterinary Pharmacology, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Rena Takahashi
- Comparative Animal Pharmacology, Department of Veterinary Science, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Natsumi Yamashita
- Veterinary Pharmacology, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Hiroki Teraoka
- Veterinary Pharmacology, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Takio Kitazawa
- Veterinary Pharmacology, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan; Comparative Animal Pharmacology, Department of Veterinary Science, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
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10
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Alom F, Miyakawa M, Matsuyama H, Nagano H, Tanahashi Y, Unno T. Possible antagonistic effects of the TRPC4 channel blocker ML204 on M 2 and M 3 muscarinic receptors in mouse ileal and detrusor smooth muscles and atrial myocardium. J Vet Med Sci 2018; 80:1407-1415. [PMID: 29973432 PMCID: PMC6160885 DOI: 10.1292/jvms.18-0197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ML204, a potent transient receptor potential canonical 4 (TRPC4) channel blocker, is often used to elucidate the involvement of TRPC4 channels in receptor-operated signaling processes in
visceral smooth muscles. In the present study, we investigated the possible antagonistic actions of ML204 on M2 and M3 muscarinic receptors, which mediate contractions
in mouse ileal and detrusor smooth muscles. In ileal and detrusor smooth muscle preparations, ML204 (3 or 10 µM) significantly inhibited electrical field stimulation
(EFS)-evoked cholinergic contractions. However, it did not significantly inhibit high K+-induced and EFS-evoked non-cholinergic contractions in the ileal preparations. When the
muscarinic agonist, carbachol was cumulatively applied, ML204 (1, 3 and 10 µM) caused a rightward parallel shift of the concentration-response curves of carbachol.
Additionally, ML204 (1, 3 and 10 µM) inhibited carbachol-induced negative chronotropic response in atrial preparations, which is mediated by M2 muscarinic
receptors. Furthermore, ML204 significantly inhibited the contractions evoked by carbachol-induced intracellular Ca2+ release, which is mediated by M3 muscarinic
receptors. These results suggested that ML204 might exhibit antagonistic actions on M2 and M3 muscarinic receptors; in addition, the inhibitory effects of ML204 against
EFS-induced cholinergic contractions might be attributed to this receptor antagonism rather than inhibition of TRPC4 channel activity. Therefore, these effects should be considered when
ML204 is used as a TRPC4 channel blocker.
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Affiliation(s)
- Firoj Alom
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Masumi Miyakawa
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hayato Matsuyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroshi Nagano
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Toshihiro Unno
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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11
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Ahammer H, Scheruebel S, Arnold R, Mayrhofer-Reinhartshuber M, Lang P, Dolgos Á, Pelzmann B, Zorn-Pauly K. Sinoatrial Beat to Beat Variability Assessed by Contraction Strength in Addition to the Interbeat Interval. Front Physiol 2018; 9:546. [PMID: 29867582 PMCID: PMC5968354 DOI: 10.3389/fphys.2018.00546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/27/2018] [Indexed: 12/01/2022] Open
Abstract
Beat to beat variability of cardiac tissue or isolated cells is frequently investigated by determining time intervals from electrode measurements in order to compute scale dependent or scale independent parameters. In this study, we utilize high-speed video camera recordings to investigate the variability of intervals as well as mechanical contraction strengths and relative contraction strengths with nonlinear analyses. Additionally, the video setup allowed us simultaneous electrode registrations of extracellular potentials. Sinoatrial node tissue under control and acetylcholine treated conditions was used to perform variability analyses by computing sample entropies and Higuchi dimensions. Beat to beat interval variabilities measured by the two recording techniques correlated very well, and therefore, validated the video analyses for this purpose. Acetylcholine treatment induced a reduction of beating rate and contraction strength, but the impact on interval variability was negligible. Nevertheless, the variability analyses of contraction strengths revealed significant differences in sample entropies and Higuchi dimensions between control and acetylcholine treated tissue. Therefore, the proposed high-speed video camera technique might represent a non-invasive tool that allows long-lasting recordings for detecting variations in beating behavior over a large range of scales.
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Affiliation(s)
- Helmut Ahammer
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Robert Arnold
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Petra Lang
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - Ádám Dolgos
- Institute for eHealth, Graz University of Applied Sciences, Graz, Austria
| | | | - Klaus Zorn-Pauly
- Institute of Biophysics, Medical University of Graz, Graz, Austria
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12
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De Witte C, Taminiau B, Flahou B, Hautekiet V, Daube G, Ducatelle R, Haesebrouck F. In-feed bambermycin medication induces anti-inflammatory effects and prevents parietal cell loss without influencing Helicobacter suis colonization in the stomach of mice. Vet Res 2018; 49:35. [PMID: 29636083 PMCID: PMC5894178 DOI: 10.1186/s13567-018-0530-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/21/2018] [Indexed: 12/18/2022] Open
Abstract
The minimum inhibitory concentration of bambermycin on three porcine Helicobacter suis strains was shown to be 8 μg/mL. The effect of in-feed medication with this antibiotic on the course of a gastric infection with one of these strains, the host response and the gastric microbiota was determined in mice, as all of these parameters may be involved in gastric pathology. In H. suis infected mice which were not treated with bambermycin, an increased number of infiltrating B-cells, T-cells and macrophages in combination with a Th2 response was demonstrated, as well as a decreased parietal cell mass. Compared to this non-treated, infected group, in H. suis infected mice medicated with bambermycin, gastric H. suis colonization was not altered, but a decreased number of infiltrating T-cells, B-cells and macrophages as well as downregulated expressions of IL-1β, IL-8M, IL-10 and IFN-γ were demonstrated and the parietal cell mass was not affected. In bambermycin treated mice that were not infected with H. suis, the number of infiltrating T-cells and expression of IL-1β were lower than in non-infected mice that did not receive bambermycin. Gastric microbiota analysis indicated that the relative abundance of bacteria that might exert unfavorable effects on the host was decreased during bambermycin supplementation. In conclusion, bambermycin did not affect H. suis colonization, but decreased gastric inflammation and inhibited the effects of a H. suis infection on parietal cell loss. Not only direct interaction of H. suis with parietal cells, but also inflammation may play a role in death of these gastric acid producing cells.
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Affiliation(s)
- Chloë De Witte
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
| | - Bernard Taminiau
- Department of Food Sciences, FARAH, Université de Liège, Avenue de Cureghem 10, 4000, Liège, Belgium
| | - Bram Flahou
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | | | - Georges Daube
- Department of Food Sciences, FARAH, Université de Liège, Avenue de Cureghem 10, 4000, Liège, Belgium
| | - Richard Ducatelle
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
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13
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Oki Y, Teraoka H, Kitazawa T. Neuropeptide Y (NPY) inhibits spontaneous contraction of the mouse atrium by possible activation of the NPY1 receptor. ACTA ACUST UNITED AC 2018; 37:23-28. [PMID: 28544313 DOI: 10.1111/aap.12055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 02/24/2017] [Accepted: 03/07/2017] [Indexed: 11/28/2022]
Abstract
Neuropeptide Y (NPY) causes various central and peripheral actions through activation of G-protein-coupled NPY receptors. Although a species-dependent difference in cardiac actions of NPY has been reported, the responses to NPY have not been examined in mice, widely used experimental animals. This study aimed to clarify the responses to NPY and the receptor subtype involved in the responses in mouse atrium. Neuropeptide Y caused negative inotropic and negative chronotropic actions in spontaneous beating right atria. Negative inotropic actions were more marked than negative chronotropic actions. Therefore, negative inotropic actions were studied in detail for evaluation of the NPY-induced cardiac actions in mouse atrium. Neuropeptide Y-induced negative inotropic actions were not affected by atropine but were abolished in the atria from pertussis toxin-treated mice. In isolated atrial preparations from reserpine-treated mice, NPY-induced negative inotropic actions were significantly attenuated. [Leu31, Pro34]-NPY, but not peptide YY, was effective in decreasing spontaneous contraction in atrial preparations. Although Y1 , Y2 , Y4 and Y5 receptor mRNAs were expressed almost equally in the brain, NPY1 receptor mRNA was dominantly expressed in the atrium. In conclusion, NPY caused negative inotropic and chronotropic actions through activation of the Y1 receptor in the mouse atrium. A high expression level of Y1 mRNA in the atrium suggests a functional role of NPY in the regulation of mouse cardiac contraction.
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Affiliation(s)
- Y Oki
- Department of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
| | - H Teraoka
- Department of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
| | - T Kitazawa
- Department of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
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14
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Soukup O, Winder M, Killi UK, Wsol V, Jun D, Kuca K, Tobin G. Acetylcholinesterase Inhibitors and Drugs Acting on Muscarinic Receptors- Potential Crosstalk of Cholinergic Mechanisms During Pharmacological Treatment. Curr Neuropharmacol 2017; 15:637-653. [PMID: 27281175 PMCID: PMC5543679 DOI: 10.2174/1570159x14666160607212615] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 04/28/2016] [Accepted: 05/31/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Pharmaceuticals with targets in the cholinergic transmission have been used for decades and are still fundamental treatments in many diseases and conditions today. Both the transmission and the effects of the somatomotoric and the parasympathetic nervous systems may be targeted by such treatments. Irrespective of the knowledge that the effects of neuronal signalling in the nervous systems may include a number of different receptor subtypes of both the nicotinic and the muscarinic receptors, this complexity is generally overlooked when assessing the mechanisms of action of pharmaceuticals. METHODS We have search of bibliographic databases for peer-reviewed research literature focused on the cholinergic system. Also, we have taken advantage of our expertise in this field to deduce the conclusions of this study. RESULTS Presently, the life cycle of acetylcholine, muscarinic receptors and their effects are reviewed in the major organ systems of the body. Neuronal and non-neuronal sources of acetylcholine are elucidated. Examples of pharmaceuticals, in particular cholinesterase inhibitors, affecting these systems are discussed. The review focuses on salivary glands, the respiratory tract and the lower urinary tract, since the complexity of the interplay of different muscarinic receptor subtypes is of significance for physiological, pharmacological and toxicological effects in these organs. CONCLUSION Most pharmaceuticals targeting muscarinic receptors are employed at such large doses that no selectivity can be expected. However, some differences in the adverse effect profile of muscarinic antagonists may still be explained by the variation of expression of muscarinic receptor subtypes in different organs. However, a complex pattern of interactions between muscarinic receptor subtypes occurs and needs to be considered when searching for selective pharmaceuticals. In the development of new entities for the treatment of for instance pesticide intoxication, the muscarinic receptor selectivity needs to be considered. Reactivators generally have a muscarinic M2 receptor acting profile. Such a blockade may engrave the situation since it may enlarge the effect of the muscarinic M3 receptor effect. This may explain why respiratory arrest is the major cause for deaths by esterase blocking.
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Affiliation(s)
- Ondrej Soukup
- Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
- National Institute of Mental Health, Klecany, Hradec Kralove, Czech Republic
| | - Michael Winder
- Institute of Neuroscience and Physiology, Department of Pharmacology, the Sahlgrenska Academy at the University of Gothenburg, Sweden
| | - Uday Kumar Killi
- Department of Biochemical Sciences, Faculty of Pharmacy, Charles University, Hradec Kralove, Czech Republic
| | - Vladimir Wsol
- Department of Biochemical Sciences, Faculty of Pharmacy, Charles University, Hradec Kralove, Czech Republic
| | - Daniel Jun
- Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Kamil Kuca
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Gunnar Tobin
- Institute of Neuroscience and Physiology, Department of Pharmacology, the Sahlgrenska Academy at the University of Gothenburg, Sweden
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15
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Filatova TS, Naumenko N, Galenko-Yaroshevsky PA, Abramochkin DV. M3 cholinoreceptors alter electrical activity of rat left atrium via suppression of L-type Ca 2+ current without affecting K + conductance. J Physiol Biochem 2016; 73:167-174. [PMID: 27858307 DOI: 10.1007/s13105-016-0538-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/09/2016] [Indexed: 11/28/2022]
Abstract
Electrophysiological effects produced by selective activation of M3 cholinoreceptors were studied in isolated left atrium preparations from rat using the standard sharp glass microelectrode technique. The stimulation of M3 receptors was obtained by application of muscarinic agonist pilocarpine (10-5 M) in the presence of selective M2 antagonist methoctramine (10-7 M). Stimulation of M3 receptors induced marked reduction of action potential duration by 14.4 ± 2.4% and 16.1 ± 2.5% of control duration measured at 50 and 90% of repolarization, respectively. This effect was completely abolished by selective M3 blocker 4-DAMP (10-8 M). In isolated myocytes obtained from the rat left atrium, similar pharmacological stimulation of M3 receptors led to suppression of peak L-type calcium current by 13.9 ± 2.6% of control amplitude (measured at +10 mV), but failed to affect K+ currents I to, I Kur, and I Kir. In the absence of M2 blocker methoctramine, pilocarpine (10-5 M) produced stronger attenuation of I CaL and induced an increase in I Kir. This additive inward rectifier current could be abolished by highly selective blocker of Kir3.1/3.4 channels tertiapin-Q (10-6 M) and therefore was identified as I KACh. Thus, in the rat atrial myocardium activation of M3 receptors leads to shortening of action potentials via suppression of I CaL, but does not enhance the major potassium currents involved in repolarization. Joint stimulation of M2 and M3 receptors produces stronger action potential shortening due to M2-mediated activation of I KACh.
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MESH Headings
- Action Potentials/drug effects
- Animals
- Animals, Outbred Strains
- Calcium Channels, L-Type/chemistry
- Calcium Channels, L-Type/metabolism
- Cardiovascular Agents/pharmacology
- Cells, Cultured
- Down-Regulation/drug effects
- Electrophysiological Phenomena/drug effects
- Escin/pharmacology
- Heart Atria/cytology
- Heart Atria/drug effects
- Heart Atria/metabolism
- In Vitro Techniques
- Mice
- Microelectrodes
- Muscarinic Agonists/pharmacology
- Muscarinic Antagonists/pharmacology
- Patch-Clamp Techniques
- Potassium Channel Blockers/pharmacology
- Potassium Channels/agonists
- Potassium Channels/metabolism
- Potassium Channels, Inwardly Rectifying/agonists
- Potassium Channels, Inwardly Rectifying/antagonists & inhibitors
- Potassium Channels, Inwardly Rectifying/metabolism
- Rats
- Receptor, Muscarinic M3/agonists
- Receptor, Muscarinic M3/antagonists & inhibitors
- Receptor, Muscarinic M3/metabolism
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Affiliation(s)
- Tatiana S Filatova
- Department of Human and Animal Physiology, Biological Faculty of the Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
| | - Nikolay Naumenko
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | | | - Denis V Abramochkin
- Department of Human and Animal Physiology, Biological Faculty of the Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia.
- Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova street, 1, Moscow, Russia.
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16
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Moreno-Galindo EG, Sanchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA. Pharmacological Conversion of a Cardiac Inward Rectifier into an Outward Rectifier Potassium Channel. Mol Pharmacol 2016; 90:334-40. [PMID: 27247338 DOI: 10.1124/mol.116.104950] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/27/2016] [Indexed: 01/20/2023] Open
Abstract
Potassium (K(+)) channels are crucial for determining the shape, duration, and frequency of action-potential firing in excitable cells. Broadly speaking, K(+) channels can be classified based on whether their macroscopic current outwardly or inwardly rectifies, whereby rectification refers to a change in conductance with voltage. Outwardly rectifying K(+) channels conduct greater current at depolarized membrane potentials, whereas inward rectifier channels conduct greater current at hyperpolarized membrane potentials. Under most circumstances, outward currents through inwardly rectifying K(+) channels are reduced at more depolarized potentials. However, the acetylcholine-gated K(+) channel (KACh) conducts current that inwardly rectifies when activated by some ligands (such as acetylcholine), and yet conducts current that outwardly rectifies when activated by other ligands (for example, pilocarpine and choline). The perplexing and paradoxical behavior of KACh channels is due to the intrinsic voltage sensitivity of the receptor that activates KACh channels, the M2 muscarinic receptor (M2R). Emerging evidence reveals that the affinity of M2R for distinct ligands varies in a voltage-dependent and ligand-specific manner. These intrinsic receptor properties determine whether current conducted by KACh channels inwardly or outwardly rectifies. This review summarizes the most recent concepts regarding the intrinsic voltage sensitivity of muscarinic receptors and the consequences of this intriguing behavior on cardiac physiology and pharmacology of KACh channels.
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Affiliation(s)
- Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Jose A Sanchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Martin Tristani-Firouzi
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
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17
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Bragança B, Oliveira-Monteiro N, Ferreirinha F, Lima PA, Faria M, Fontes-Sousa AP, Correia-de-Sá P. Ion Fluxes through KCa2 (SK) and Cav1 (L-type) Channels Contribute to Chronoselectivity of Adenosine A1 Receptor-Mediated Actions in Spontaneously Beating Rat Atria. Front Pharmacol 2016; 7:45. [PMID: 27014060 PMCID: PMC4780064 DOI: 10.3389/fphar.2016.00045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/18/2016] [Indexed: 11/24/2022] Open
Abstract
Impulse generation in supraventricular tissue is inhibited by adenosine and acetylcholine via the activation of A1 and M2 receptors coupled to inwardly rectifying GIRK/KIR3.1/3.4 channels, respectively. Unlike M2 receptors, bradycardia produced by A1 receptors activation predominates over negative inotropy. Such difference suggests that other ion currents may contribute to adenosine chronoselectivity. In isolated spontaneously beating rat atria, blockade of KCa2/SK channels with apamin and Cav1 (L-type) channels with nifedipine or verapamil, sensitized atria to the negative inotropic action of the A1 agonist, R-PIA, without affecting the nucleoside negative chronotropy. Patch-clamp experiments in the whole-cell configuration mode demonstrate that adenosine, via A1 receptors, activates the inwardly-rectifying GIRK/KIR3.1/KIR3.4 current resulting in hyperpolarization of atrial cardiomyocytes, which may slow down heart rate. Conversely, the nucleoside inactivates a small conductance Ca2+-activated KCa2/SK outward current, which eventually reduces the repolarizing force and thereby prolong action potentials duration and Ca2+ influx into cardiomyocytes. Immunolocalization studies showed that differences in A1 receptors distribution between the sinoatrial node and surrounding cardiomyocytes do not afford a rationale for adenosine chronoselectivity. Immunolabelling of KIR3.1, KCa2.2, KCa2.3, and Cav1 was also observed throughout the right atrium. Functional data indicate that while both A1 and M2 receptors favor the opening of GIRK/KIR3.1/3.4 channels modulating atrial chronotropy, A1 receptors may additionally restrain KCa2/SK activation thereby compensating atrial inotropic depression by increasing the time available for Ca2+ influx through Cav1 (L-type) channels.
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Affiliation(s)
- Bruno Bragança
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
| | - Nádia Oliveira-Monteiro
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
| | - Pedro A Lima
- Departamento de Química e Bioquímica, Faculdade de Ciências, Centro de Química e Bioquímica, Universidade de Lisboa Lisboa, Portugal
| | - Miguel Faria
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
| | - Ana P Fontes-Sousa
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia - Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto (UP) Porto, Portugal
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18
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Tinker A, Finlay M, Nobles M, Opel A. The contribution of pathways initiated via the Gq\11 G-protein family to atrial fibrillation. Pharmacol Res 2016; 105:54-61. [DOI: 10.1016/j.phrs.2015.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 01/28/2023]
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19
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Tomankova H, Valuskova P, Varejkova E, Rotkova J, Benes J, Myslivecek J. The M2 muscarinic receptors are essential for signaling in the heart left ventricle during restraint stress in mice. Stress 2015; 18:208-20. [PMID: 25586419 DOI: 10.3109/10253890.2015.1007345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We hypothesized that muscarinic receptors (MRs) in the heart have a role in stress responses and thus investigated changes in MR signaling (gene expression, number of receptors, adenylyl cyclase (AC), phospholipase C (PLC), protein kinase A and C (PKA and PKC) and nitric oxide synthase [NOS]) in the left ventricle, together with telemetric measurement of heart rate (HR) in mice (wild type [WT] and M2 knockout [KO]) during and after one (1R) or seven sessions (7R) of restraint stress (seven mice per group). Stress decreased M2 MR mRNA and cell surface MR in the left ventricle in WT mice. In KO mice, 1R, but not 7R, decreased surface MR. Similarly, AC activity was decreased in WT mice after 1R and 7R, whereas in KO mice, there was no change. PLC activity was also decreased after 1R in WT and KO mice. This is in accord with the concept that cAMP is a key player in HR regulation. No change was found with stress in NOS activity. Amount of AC and PKA protein was not changed, but was altered for PKC isoenzymes (PKCα, β, γ, η and ϵ (increased) in KO mice, and PKCι (increased) in WT mice). KO mice were more susceptible to stress as shown by inability to compensate HR during 120 min following repeated stress. The results imply that not only M2 but also M3 are involved in stress signaling and in allostasis. We conclude that for a normal stress response, the expression of M2 MR to mediate vagal responses is essential.
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Affiliation(s)
- Hana Tomankova
- 1st Faculty of Medicine, Institute of Physiology, Charles University , Prague , Czech Republic
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20
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Abramochkin DV, Tapilina SV, Vornanen M. A new potassium ion current induced by stimulation of M2 cholinoreceptors in fish atrial myocytes. ACTA ACUST UNITED AC 2014; 217:1745-51. [PMID: 24526726 DOI: 10.1242/jeb.098509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A novel potassium ion current induced by muscarinic stimulation (IKACh2) is characterized in atrial cardiomyocytes of teleost fishes (crucian carp, Carassius carassius; rainbow trout, Oncorhynchus mykiss) by means of the whole-cell patch-clamp technique. The current is elicited in atrial, but not ventricular, cells by application of carbamylcholine (CCh) in moderate to high concentrations (10(-7)-10(-4) mol l(-1)). It can be distinguished from the classic IKACh, activated by the βγ-subunit of the Gi-protein, because of its low sensitivity to Ba(2+) ions and distinct current-voltage relationship with a very small inward current component. Ni(2+) ions (5 mmol l(-1)) and KB-R7943 (10(-5) mol l(-1)), non-selective blockers of the sodium-calcium exchange current (INCX), strongly reduced and completely abolished, respectively, the IKACh2. Therefore, IKACh2 was initially regarded as a CCh-induced outward component of the INCX. However, the current is not affected by either exclusion of intracellular Na(+) or extracellular Ca(2+), but is completely abolished by intracellular perfusion with K(+)-free solution. Atropine (10(-6) mol l(-1)), a non-selective muscarinic blocker, completely eliminated the IKACh2. A selective antagonist of M2 cholinoreceptors, AF-DX 116 (2×10(-7) mol l(-1)) and an M3 antagonist, 4-DAMP (10(-9) mol l(-1)), decreased IKACh2 by 84.4% and 16.6%, respectively. Pertussis toxin, which irreversibly inhibits Gi-protein coupled to M2 receptors, reduced the current by 95%, when applied into the pipette solution. It is concluded that IKACh2, induced by stimulation of M2 cholinoceptors and subsequent Gi-protein activation, represents a new molecular target for the cardiac parasympathetic innervation.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory, 1, 12, Moscow 119991, Russia Department of Fundamental and Applied Physiology, Russian National Research Medical University, Moscow 117997, Russia
| | - Svetlana V Tapilina
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory, 1, 12, Moscow 119991, Russia
| | - Matti Vornanen
- Department of Biology, University of Eastern Finland, FI-80101 Joensuu, Finland
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A ganglionic stimulant, 1,1-dimethyl-4-phenylpiperazinium, caused both cholinergic and adrenergic responses in the isolated mouse atrium. Eur J Pharmacol 2013; 704:7-14. [DOI: 10.1016/j.ejphar.2013.02.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 02/01/2013] [Accepted: 02/07/2013] [Indexed: 11/22/2022]
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Benes J, Varejkova E, Farar V, Novakova M, Myslivecek J. Decrease in heart adrenoceptor gene expression and receptor number as compensatory tool for preserved heart function and biological rhythm in M(2) KO animals. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:1161-73. [PMID: 23093370 DOI: 10.1007/s00210-012-0800-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 10/05/2012] [Indexed: 11/26/2022]
Abstract
Muscarinic receptors (MR) are main cardioinhibitory receptors. We investigated the changes in gene expression, receptor number, echocardiography, muscarinic/adrenergic agonist/antagonist changes in heart rate (HR) and HR biorhythm in M(2) KO mice (mice lacking the main cardioinhibitory receptors) in the left ventricle (LV) and right ventricle (RV). We hypothesize that the disruption of M(2) MR, key players in parasympathetic bradycardia, would change the number of receptors with antagonistic effects on the heart (β(1)- and β(2)-adrenoceptors, BAR), while the function of the heart would be changed only marginally. We have found changes in LV, but not in RV: decrease in M(3) MR, β(1)- and β(2)-adrenoceptor gene expressions that were accompanied by a decrease in MR and BAR receptor binding. No changes were found both in LV systolic and diastolic function as assessed by echocardiography (e.g., similar LV end-systolic and end-diastolic diameter, fractional shortening, mitral flow characteristics, and maximal velocity in LV outflow tract). We have found only marginal changes in specific HR biorhythm parameters. The effects of isoprenaline and propranolol on HR were similar in WT and KO (but with lesser extent). Atropine was not able to increase HR in KO animals. Carbachol decreased the HR in WT but increased HR in KO, suggesting the presence of cardiostimulatory MR. Therefore, we can conclude that although the main cardioinhibitory receptors are not present in the heart, the function is not much affected. As possible mechanisms of almost normal cardiac function, the decreases of both β(1)- and β(2)-adrenoceptor gene expression and receptor binding should be considered.
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Affiliation(s)
- Jan Benes
- Institute of Physiology, 1st Faculty of Medicine, Charles University, Albertov 5, 128 00, Prague, Czech Republic
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Harada N, Ochi K, Yaosaka N, Teraoka H, Hiraga T, Iwanaga T, Unno T, Komori S, Yamada M, Kitazawa T. Immunohistochemical and functional studies for M3muscarinic receptors and cyclo-oxygenase-2 expressed in the mouse atrium. ACTA ACUST UNITED AC 2012; 32:41-52. [DOI: 10.1111/j.1474-8673.2012.00472.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/08/2012] [Accepted: 04/15/2012] [Indexed: 11/30/2022]
Affiliation(s)
- N. Harada
- Department of Veterinary Medicine; Rakuno Gakuen University; Ebetsu; Hokkaido; 069-8501; Japan
| | - K. Ochi
- Department of Veterinary Medicine; Rakuno Gakuen University; Ebetsu; Hokkaido; 069-8501; Japan
| | - N. Yaosaka
- Department of Veterinary Science; Rakuno Gakuen University; Ebetsu; Hokkaido; 069-8501; Japan
| | - H. Teraoka
- Department of Veterinary Medicine; Rakuno Gakuen University; Ebetsu; Hokkaido; 069-8501; Japan
| | - T. Hiraga
- Department of Veterinary Medicine; Rakuno Gakuen University; Ebetsu; Hokkaido; 069-8501; Japan
| | - T. Iwanaga
- Department of Functional Morphology, Laboratory of Histology and Cytology; Hokkaido University Graduate School of Medicine; Sapporo; 060-8638; Japan
| | - T. Unno
- Laboratory of Pharmacology, Faculty of Applied Biological Science; Gifu University; Gifu; 501-1193; Japan
| | - S. Komori
- Laboratory of Pharmacology, Faculty of Applied Biological Science; Gifu University; Gifu; 501-1193; Japan
| | - M. Yamada
- Common Resources Group; Okinawa Institute of Science and Technology; Okinawa; 904-0411; Japan
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Jones DL, Tuomi JM, Chidiac P. Role of Cholinergic Innervation and RGS2 in Atrial Arrhythmia. Front Physiol 2012; 3:239. [PMID: 22754542 PMCID: PMC3386567 DOI: 10.3389/fphys.2012.00239] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 06/12/2012] [Indexed: 01/25/2023] Open
Abstract
The heart receives sympathetic and parasympathetic efferent innervation as well as the ability to process information internally via an intrinsic cardiac autonomic nervous system (ICANS). For over a century, the role of the parasympathetics via vagal acetylcholine release was related to controlling primarily heart rate. Although in the late 1800s shown to play a role in atrial arrhythmia, the myocardium took precedence from the mid-1950s until in the last decade a resurgence of interest in the autonomics along with signaling cascades, regulators, and ion channels. Originally ignored as being benign and thus untreated, recent emphasis has focused on atrial arrhythmia as atrial fibrillation (AF) is the most common arrhythmia seen by the general practitioner. It is now recognized to have significant mortality and morbidity due to resultant stroke and heart failure. With the aging population, there will be an unprecedented increased burden on health care resources. Although it has been known for more than half a century that cholinergic stimulation can initiate AF, the classical concept focused on the M2 receptor and its signaling cascade including RGS4, as these had been shown to have predominant effects on nodal function (heart rate and conduction block) as well as contractility. However, recent evidence suggests that the M3 receptor may also playa role in initiation and perpetuation of AF and thus RGS2, a putative regulator of the M3 receptor, may be a target for therapeutic intervention. Mice lacking RGS2 (RGS2−/−), were found to have significantly altered electrophysiological atrial responses and were more susceptible to electrically induced AF. Vagally induced or programmed stimulation-induced AF could be blocked by the selective M3R antagonist, darifenacin. These results suggest a potential surgical target (ICANS) and pharmacological targets (M3R, RGS2) for the management of AF.
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Affiliation(s)
- Douglas L Jones
- Department of Physiology and Pharmacology, The University of Western Ontario London, ON, Canada
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Abstract
The physiological role of muscarinic receptors is highly complex and, although not completely understood, has become clearer over the last decade. Recent pharmacological evidence with novel compounds, together with data from transgenic mice, suggests that all five subtypes have defined functions in the nervous system as well as mediating the non neuronal, hormonal actions of acetylcholine. Numerous novel agonists, allosteric regulators, and antagonists have now been identified with authentic subtype specificity in vitro and in vivo. These compounds provide additional pharmacological opportunities for selective subtype modulation as well as a new generation of muscarinic receptor-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Corning Life Sciences, 900 Chelmsford St., MA 01851, Lowell, USA.
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Abramochkin DV, Tapilina SV, Sukhova GS, Nikolsky EE, Nurullin LF. Functional M3 cholinoreceptors are present in pacemaker and working myocardium of murine heart. Pflugers Arch 2012; 463:523-9. [PMID: 22350728 DOI: 10.1007/s00424-012-1075-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 01/17/2012] [Accepted: 01/23/2012] [Indexed: 11/27/2022]
Abstract
The presence of M3 cholinoreceptors and their role in mediation of action potential waveform modulation were determined by immunolabeling of receptor proteins and standard microelectrode technique, respectively. The sinoatrial node (SAN), which was determined as a connexin 43 negative area within the intercaval region, the surrounding atrial tissue, and the working ventricular myocardium exhibited labeling of both M3 and M2 receptors. However, the density of M3 and M2 labeling was about twofold higher in the SAN compared to working myocardium. The stimulation of M3 receptors was obtained by application of nonselective M1 and M3 muscarinic agonist pilocarpine (10(-5) M) in the presence of selective M2 blocker methoctramine (10(-7) M). Stimulation of M3 receptors provoked marked shortening of action potential duration in atrial and ventricular working myocardium. In the SAN, M3 stimulation leads to a significant reduction of sinus rhythm rate accompanied with slowing of diastolic depolarization and increase of action potential upstroke velocity. All electrophysiological effects of selective M3 stimulation were suppressed by specific blocker of M3 receptors 4-DAMP (10(-8) M). We conclude that M3 cholinoreceptors are present in pacemaker and working myocardium of murine heart, where they mediate negative cholinergic effects: slowing of sinus rhythm and shortening of action potentials.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory 1, Moscow, Russia.
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Strange PG. Use of the GTPγS ([35S]GTPγS and Eu-GTPγS) binding assay for analysis of ligand potency and efficacy at G protein-coupled receptors. Br J Pharmacol 2011; 161:1238-49. [PMID: 20662841 DOI: 10.1111/j.1476-5381.2010.00963.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
UNLABELLED In this review I consider assays for G protein-coupled receptor (GPCR) activity based on the binding of labelled analogues of GTPγS ([(35) S]GTPγS or Eu-GTPγS) to G proteins in tissues (GTPγS binding assays). Such assays provide convenient measures of GPCR activity close to the receptor in the signalling cascade. In order to set up a GTPγS binding assay, the requirements of the assay must be considered. These are tissue source, GTPγS analogue, G protein, GDP, Mg(2+) /Na(+) ions, saponin, incubation time. The assay, once optimized, can be used to generate concentration/response curves for GPCRs signalling via G(i/o) proteins (or to other G proteins with a modified assay) and actions of agonists, inverse agonists and antagonists may, in principle, be assessed. For agonists and inverse agonists, data for the maximal agonist effect, the concentration of ligand giving a half-maximal response and the Hill coefficient may be derived. For antagonists, data for the equilibrium dissociation constant can be obtained. The mechanistic basis of the assay is considered. Although the assay can be used to profile ligands, under the conditions it is used, it may not be measuring the same event that determines GPCR action in cells. LINKED ARTICLES This article is part of a themed section on Analytical Receptor Pharmacology in Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2010.161.issue-6
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Affiliation(s)
- Philip G Strange
- School of Pharmacy, University of Reading, Whiteknights, Reading, UK.
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Harada K, Matsuoka H, Sata T, Warashina A, Inoue M. Identification and Role of Muscarinic Receptor Subtypes Expressed in Rat Adrenal Medullary Cells. J Pharmacol Sci 2011; 117:253-64. [DOI: 10.1254/jphs.11125fp] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022] Open
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Lagerqvist EL, Finnin BA, Pouton CW, Haynes JM. Endothelin-1 and angiotensin II modulate rate and contraction amplitude in a subpopulation of mouse embryonic stem cell-derived cardiomyocyte-containing bodies. Stem Cell Res 2010; 6:23-33. [PMID: 20970401 DOI: 10.1016/j.scr.2010.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 09/08/2010] [Accepted: 09/10/2010] [Indexed: 11/27/2022] Open
Abstract
Embryonic stem cell-derived cardiomyocytes (ESC-CMs) have applications in understanding cardiac disease pathophysiology, pharmacology, and toxicology. Comprehensive characterization of their basic physiological and pharmacological properties is critical in determining the suitability of ESC-CMs as models of cardiac activity. In this study we use video microscopy and quantitative PCR to investigate the responses of mouse ESC-CMs to adrenoceptor, muscarinic, angiotensin II (Ang II), and endothelin-1 (ET-1) receptor activation. Isoprenaline (10 nM-10 μM) increased beating rate and contraction amplitude in all beating bodies (BBs), whereas carbachol (up to 1 μM) and the I(f) channel blocker ZD-7288 (10 μM) decreased contraction frequency. ET-1 (0.01-100 nM) reduced contraction amplitude in all BBs and increased contraction frequency in 50% of BBs; these effects were blocked by the ET(A) receptor antagonist BQ123 (250 nM). Ang II (0.01 nM-1 μM) increased both contraction amplitude (all BBs) and frequency (in 50% of BBs), effects blocked, respectively, by losartan (100 nM) and PD123,319 (200 nM). These results indicate the presence of functional ET(A) and both AT₁ and AT₂ receptors in murine ESC-CMs, but their expression and or activity appears to be evident only in a limited set of BBs.
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Affiliation(s)
- E L Lagerqvist
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Melbourne, Australia
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Tuomi JM, Chidiac P, Jones DL. Evidence for enhanced M3 muscarinic receptor function and sensitivity to atrial arrhythmia in the RGS2-deficient mouse. Am J Physiol Heart Circ Physiol 2009; 298:H554-61. [PMID: 19966055 DOI: 10.1152/ajpheart.00779.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia seen in general practice. Muscarinic ACh receptors (M2R, M3R) are involved in vagally induced AF. M2R and M3R activate the heterotrimeric G proteins, G(i) and G(q), respectively, by promoting GTP binding, and these in turn activate distinct K(+) channels. Signaling is terminated by GTP hydrolysis, a process accelerated by regulator of G protein signaling (RGS) proteins. RGS2 is selective for G(q) and thus may regulate atrial M3R signaling. We hypothesized that knockout of RGS2 (RGS2(-/-)) would render the atria more susceptible to electrically induced AF. One-month-old male RGS2(-/-) and C57BL/6 wild-type (WT) mice were instrumented for intracardiac electrophysiology. Atrial effective refractory periods (AERPs) were also determined in the absence and presence of carbachol, atropine, and/or the selective M3R antagonist darifenacin. Susceptibility to electrically induced AF used burst pacing and programmed electrical stimulation with one extrastimulus. Real-time RT-PCR measured atrial and ventricular content of RGS2, RGS4, M2R, M3R, and M4R mRNA. AERP was lower in RGS2(-/-) compared with WT mice in both the high right atrium (HRA) (30 +/- 1 vs. 34 +/- 1 ms, P < 0.05) and mid right atrium (MRA) (21 +/- 1 vs. 24 +/- 1 ms, P < 0.05). Darifenacin eliminated this difference (HRA: 37 +/- 2 vs. 39 +/- 2 ms, and MRA: 30 +/- 2 vs. 30 +/- 1, P > 0.4). RGS2(-/-) were more susceptible than WT mice to atrial tachycardia/fibrillation (AT/F) induction (11/22 vs. 1/25, respectively, P < 0.05). Muscarinic receptor expression did not differ between strains, whereas M2R expression was 70-fold higher than M3R (P < 0.01). These results suggest that RGS2 is an important cholinergic regulator in the atrium and that RGS2(-/-) mice have enhanced susceptibility to AT/F via enhanced M3 muscarinic receptor activity.
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Affiliation(s)
- Jari M Tuomi
- Department of Physiology and Pharmacology, University of Western Ontario, London Health Science Center, London, Ontario, Canada
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Hara Y, Ike A, Tanida R, Okada M, Yamawaki H. Involvement of Cyclooxygenase-2 in Carbachol-Induced Positive Inotropic Response in Mouse Isolated Left Atrium. J Pharmacol Exp Ther 2009; 331:808-15. [DOI: 10.1124/jpet.109.156992] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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