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Findlay I, Pasqualin C, Yu A, Maupoil V, Bredeloux P. Selective Inhibition of Pulmonary Vein Excitability by Constitutively Active GIRK Channels Blockade in Rats. Int J Mol Sci 2023; 24:13629. [PMID: 37686437 PMCID: PMC10487709 DOI: 10.3390/ijms241713629] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/25/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023] Open
Abstract
Pulmonary veins (PV) are the main source of ectopy, triggering atrial fibrillation. This study investigated the roles of G protein-coupled inwardly rectifying potassium (GIRK) channels in the PV and the left atrium (LA) of the rat. Simultaneous intracellular microelectrode recording from the LA and the PV of the rat found that in the presence or absence of acetylcholine, the GIRK channel blocker tertiapin-Q induced AP duration elongation in the LA and the loss of over-shooting AP in the PV, suggesting the presence of constitutively active GIRK channels in these tissues. Patch-clamp recordings from isolated myocytes showed that tertiapin-Q inhibited a basal inwardly rectified background current in PV cells with little effect in LA cells. Experiments with ROMK1 and KCa1.1 channel blockers ruled out the possibility of an off-target effect. Western blot showed that GIRK4 subunit expression was greater in PV cardiomyocytes, which may explain the differences observed between PV and LA in response to tertiapin-Q. In conclusion, GIRK channels blockade abolishes AP only in the PV, providing a molecular target to induce electrical disconnection of the PV from the LA.
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Affiliation(s)
- Ian Findlay
- Laboratoire de Pharmacologie, Faculté de Pharmacie, Université de Tours, 37200 Tours, France;
| | - Côme Pasqualin
- EA4245, Transplantation, Immunologie et Inflammation, Université de Tours, 37200 Tours, France; (C.P.); (A.Y.); (V.M.)
| | - Angèle Yu
- EA4245, Transplantation, Immunologie et Inflammation, Université de Tours, 37200 Tours, France; (C.P.); (A.Y.); (V.M.)
| | - Véronique Maupoil
- EA4245, Transplantation, Immunologie et Inflammation, Université de Tours, 37200 Tours, France; (C.P.); (A.Y.); (V.M.)
| | - Pierre Bredeloux
- EA4245, Transplantation, Immunologie et Inflammation, Université de Tours, 37200 Tours, France; (C.P.); (A.Y.); (V.M.)
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Oancea AF, Jigoranu RA, Morariu PC, Miftode RS, Trandabat BA, Iov DE, Cojocaru E, Costache II, Baroi LG, Timofte DV, Tanase DM, Floria M. Atrial Fibrillation and Chronic Coronary Ischemia: A Challenging Vicious Circle. Life (Basel) 2023; 13:1370. [PMID: 37374152 DOI: 10.3390/life13061370] [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: 04/12/2023] [Revised: 05/31/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Atrial fibrillation, the most frequent arrhythmia in clinical practice and chronic coronary syndrome, is one of the forms of coronary ischemia to have a strong dual relationship. Atrial fibrillation may accelerate atherosclerosis and may increase oxygen consumption in the myocardium, creating a mismatch between supply and demand, thus promoting the development or worsening of coronary ischemia. Chronic coronary syndrome alters the structure and function of gap junction proteins, affecting the conduction of action potential and leading to ischemic necrosis of cardiomyocytes and their replacement with fibrous tissue, in this way sustaining the focal ectopic activity in atrial myocardium. They have many risk factors in common, such as hypertension, obesity, type 2 diabetes mellitus, and dyslipidemia. It is vital for the prognosis of patients to break this vicious circle by controlling risk factors, drug therapies, of which antithrombotic therapy may sometimes be challenging in terms of prothrombotic and bleeding risk, and interventional therapies (revascularization and catheter ablation).
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Affiliation(s)
- Alexandru Florinel Oancea
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Cardiology Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Raul Alexandru Jigoranu
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Cardiology Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Paula Cristina Morariu
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Internal Medicine Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Radu-Stefan Miftode
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Cardiology Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Bogdan Andrei Trandabat
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Cardiology Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Diana Elena Iov
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Internal Medicine Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Elena Cojocaru
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Department of Morphofunctional Sciences-Pathology, Pediatric Hospital, 700115 Iasi, Romania
| | - Irina Iuliana Costache
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Cardiology Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Livia Genoveva Baroi
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Surgery Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Daniel Vasile Timofte
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Surgery Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Daniela Maria Tanase
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Internal Medicine Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
| | - Mariana Floria
- Department of Internal Medicine, Faculty of Medicine, University of Medicine and Pharmacy Grigore T. Popa, 700115 Iasi, Romania
- Internal Medicine Clinic, St. Spiridon Emergency Hospital, 700115 Iasi, Romania
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Preferential Expression of Ca2+-Stimulable Adenylyl Cyclase III in the Supraventricular Area, Including Arrhythmogenic Pulmonary Vein of the Rat Heart. Biomolecules 2022; 12:biom12050724. [PMID: 35625651 PMCID: PMC9138642 DOI: 10.3390/biom12050724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 12/10/2022] Open
Abstract
Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca2+-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca2+ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca2+ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes.
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