Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation
Mechanisms for the α-adrenoceptor-mediated positive inotropy in neonatal mouse ventricular myocardium were studied with isolated myocardial preparations. The phenylephrine-induced positive inotropy was suppressed by prazosin, nifedipine, and chelerythrine, a protein kinase C inhibitor, but not by SE...
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MDPI AG
2023-02-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/4/3926 |
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| author | Shogo Hamaguchi Ikue Morinou Yuko Shiseki Ayako Mikami Maika Seki Iyuki Namekata Hikaru Tanaka |
| author_facet | Shogo Hamaguchi Ikue Morinou Yuko Shiseki Ayako Mikami Maika Seki Iyuki Namekata Hikaru Tanaka |
| author_sort | Shogo Hamaguchi |
| collection | DOAJ |
| description | Mechanisms for the α-adrenoceptor-mediated positive inotropy in neonatal mouse ventricular myocardium were studied with isolated myocardial preparations. The phenylephrine-induced positive inotropy was suppressed by prazosin, nifedipine, and chelerythrine, a protein kinase C inhibitor, but not by SEA0400, a selective Na<sup>+</sup>/Ca<sup>2+</sup> exchanger inhibitor. Phenylephrine increased the L-type Ca<sup>2+</sup> channel current and prolonged the action potential duration, while the voltage-dependent K<sup>+</sup> channel current was not influenced. In the presence of cromakalim, an ATP-sensitive K<sup>+</sup> channel opener, the phenylephrine-induced prolongation of action potential duration, as well as the positive inotropy, were smaller than in the absence of cromakalim. These results suggest that the α-adrenoceptor-mediated positive inotropy is mediated by an increase in Ca<sup>2+</sup> influx through the L-type Ca<sup>2+</sup> channel, and the concomitant increase in action potential duration acts as an enhancing factor. |
| first_indexed | 2024-03-11T08:41:47Z |
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| id | doaj.art-548858318c4f4d3aa3f41973cbbe5090 |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-11T08:41:47Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-548858318c4f4d3aa3f41973cbbe50902023-11-16T21:07:01ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-02-01244392610.3390/ijms24043926Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential ProlongationShogo Hamaguchi0Ikue Morinou1Yuko Shiseki2Ayako Mikami3Maika Seki4Iyuki Namekata5Hikaru Tanaka6Department of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanDepartment of Pharmacology, Faculty of Pharmacological Science, Toho University, Chiba 274-8510, JapanMechanisms for the α-adrenoceptor-mediated positive inotropy in neonatal mouse ventricular myocardium were studied with isolated myocardial preparations. The phenylephrine-induced positive inotropy was suppressed by prazosin, nifedipine, and chelerythrine, a protein kinase C inhibitor, but not by SEA0400, a selective Na<sup>+</sup>/Ca<sup>2+</sup> exchanger inhibitor. Phenylephrine increased the L-type Ca<sup>2+</sup> channel current and prolonged the action potential duration, while the voltage-dependent K<sup>+</sup> channel current was not influenced. In the presence of cromakalim, an ATP-sensitive K<sup>+</sup> channel opener, the phenylephrine-induced prolongation of action potential duration, as well as the positive inotropy, were smaller than in the absence of cromakalim. These results suggest that the α-adrenoceptor-mediated positive inotropy is mediated by an increase in Ca<sup>2+</sup> influx through the L-type Ca<sup>2+</sup> channel, and the concomitant increase in action potential duration acts as an enhancing factor.https://www.mdpi.com/1422-0067/24/4/3926mouse ventricleα-adrenergic receptorL-type Ca<sup>2+</sup> channelaction potential duration |
| spellingShingle | Shogo Hamaguchi Ikue Morinou Yuko Shiseki Ayako Mikami Maika Seki Iyuki Namekata Hikaru Tanaka Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation International Journal of Molecular Sciences mouse ventricle α-adrenergic receptor L-type Ca<sup>2+</sup> channel action potential duration |
| title | Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation |
| title_full | Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation |
| title_fullStr | Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation |
| title_full_unstemmed | Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation |
| title_short | Mechanisms for the α-Adrenoceptor-Mediated Positive Inotropy in Mouse Ventricular Myocardium: Enhancing Effect of Action Potential Prolongation |
| title_sort | mechanisms for the α adrenoceptor mediated positive inotropy in mouse ventricular myocardium enhancing effect of action potential prolongation |
| topic | mouse ventricle α-adrenergic receptor L-type Ca<sup>2+</sup> channel action potential duration |
| url | https://www.mdpi.com/1422-0067/24/4/3926 |
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