| Dokumentenart: | Artikel | ||||
|---|---|---|---|---|---|
| Titel eines Journals oder einer Zeitschrift: | Cardiovascular Research | ||||
| Verlag: | OXFORD UNIV PRESS | ||||
| Ort der Veröffentlichung: | OXFORD | ||||
| Band: | 107 | ||||
| Nummer des Zeitschriftenheftes oder des Kapitels: | 1 | ||||
| Seitenbereich: | S. 184-196 | ||||
| Datum: | 2015 | ||||
| Institutionen: | Medizin > Lehrstuhl für Innere Medizin II | ||||
| Identifikationsnummer: |
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| Stichwörter / Keywords: | LATE SODIUM CURRENT; RAT VENTRICULAR MYOCYTES; RETICULUM CA2+ LEAK; PROTEIN-KINASE-II; TOXIN ATX-II; SARCOPLASMIC-RETICULUM; FIBRILLATION; RANOLAZINE; CURRENTS; PHOSPHOLAMBAN; Late Na current; Antiarrhythmic drugs; Atrial fibrillation; Protein kinases; SR-Ca2+-leak | ||||
| Dewey-Dezimal-Klassifikation: | 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin | ||||
| Status: | Veröffentlicht | ||||
| Begutachtet: | Ja, diese Version wurde begutachtet | ||||
| An der Universität Regensburg entstanden: | Ja | ||||
| Dokumenten-ID: | 60294 |
Web of ScienceZusammenfassung
Aims Enhanced cardiac late Na current (late I-Na) and increased sarcoplasmic reticulum (SR)-Ca2+-leak are both highly arrhythmogenic. This study seeks to identify signalling pathways interconnecting late I-Na and SR-Ca2+-leak in atrial cardiomyocytes (CMs). Methods and results In murine atrial CMs, SR-Ca2+-leak was increased by the late I-Na enhancer Anemonia sulcata toxin II (ATX-II). An ...
Zusammenfassung
Aims Enhanced cardiac late Na current (late I-Na) and increased sarcoplasmic reticulum (SR)-Ca2+-leak are both highly arrhythmogenic. This study seeks to identify signalling pathways interconnecting late I-Na and SR-Ca2+-leak in atrial cardiomyocytes (CMs). Methods and results In murine atrial CMs, SR-Ca2+-leak was increased by the late I-Na enhancer Anemonia sulcata toxin II (ATX-II). An inhibition of Ca2+/calmodulin-dependent protein kinase II (Autocamide-2-related inhibitory peptide), protein kinase A (H89), or late I-Na (Ranolazine or Tetrodotoxin) all prevented ATX-II-dependent SR-Ca2+-leak. The SR-Ca2+-leak induction by ATX-II was not detected when either the Na+/Ca2+ exchanger was inhibited (KBR) or in CaMKIIdc-knockout mice. FRET measurements revealed increased cAMP levels upon ATX-II stimulation, which could be prevented by inhibition of adenylyl cyclases (ACs) 5 and 6 (NKY 80) but not by inhibition of phosphodiesterases (IBMX), suggesting PKA activation via an AC-dependent increase of cAMP levels. Western blots showed late I-Na-dependent hyperphosphorylation of CaMKII as well as PKA target sites at ryanodine receptor type-2 (-S2814 and -S2808) and phospholamban (-Thr17, -S16). Enhancement of late I-Na did not alter Ca2+-transient amplitude or SR-Ca2+-load. However, upon late I-Na activation and simultaneous CaMKII inhibition, Ca2+-transient amplitude and SR-Ca2+-load were increased, whereas PKA inhibition reduced Ca2+-transient amplitude and load and additionally slowed Ca2+ elimination. In atrial CMs from patients with atrial fibrillation, inhibition of late I-Na, CaMKII, or PKA reduced the SR-Ca2+-leak. Conclusion Late I-Na exerts distinct effects on Ca2+ homeostasis in atrial myocardium through activation of CaMKII and PKA. Inhibition of late I-Na represents a potential approach to attenuate CaMKII activation and decreases SR-Ca2+-leak in atrial rhythm disorders. The interconnection with the cAMP/PKA system further increases the antiarrhythmic potential of late I-Na inhibition.
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