Late INa increases diastolic SR-Ca2+-leak in atrial myocardium by activating PKA and CaMKII
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Late INa increases diastolic SR-Ca2+-leak in atrial myocardium by activating PKA and CaMKII. / Fischer, Thomas H; Herting, Jonas; Mason, Fleur E; Hartmann, Nico; Watanabe, Saera; Nikolaev, Viacheslav O; Sprenger, Julia U; Fan, Peidong; Yao, Lina; Popov, Aron-Frederik; Danner, Bernhard C; Schöndube, Friedrich; Belardinelli, Luiz; Hasenfuss, Gerd; Maier, Lars S; Sossalla, Samuel.
In: CARDIOVASC RES, Vol. 107, No. 1, 01.07.2015, p. 184-96.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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T1 - Late INa increases diastolic SR-Ca2+-leak in atrial myocardium by activating PKA and CaMKII
AU - Fischer, Thomas H
AU - Herting, Jonas
AU - Mason, Fleur E
AU - Hartmann, Nico
AU - Watanabe, Saera
AU - Nikolaev, Viacheslav O
AU - Sprenger, Julia U
AU - Fan, Peidong
AU - Yao, Lina
AU - Popov, Aron-Frederik
AU - Danner, Bernhard C
AU - Schöndube, Friedrich
AU - Belardinelli, Luiz
AU - Hasenfuss, Gerd
AU - Maier, Lars S
AU - Sossalla, Samuel
N1 - © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.
PY - 2015/7/1
Y1 - 2015/7/1
N2 - AIMS: Enhanced cardiac late Na current (late INa) and increased sarcoplasmic reticulum (SR)-Ca(2+)-leak are both highly arrhythmogenic. This study seeks to identify signalling pathways interconnecting late INa and SR-Ca(2+)-leak in atrial cardiomyocytes (CMs).METHODS AND RESULTS: In murine atrial CMs, SR-Ca(2+)-leak was increased by the late INa enhancer Anemonia sulcata toxin II (ATX-II). An inhibition of Ca(2+)/calmodulin-dependent protein kinase II (Autocamide-2-related inhibitory peptide), protein kinase A (H89), or late INa (Ranolazine or Tetrodotoxin) all prevented ATX-II-dependent SR-Ca(2+)-leak. The SR-Ca(2+)-leak induction by ATX-II was not detected when either the Na(+)/Ca(2+) exchanger was inhibited (KBR) or in CaMKIIδc-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 INa-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 INa did not alter Ca(2+)-transient amplitude or SR-Ca(2+)-load. However, upon late INa activation and simultaneous CaMKII inhibition, Ca(2+)-transient amplitude and SR-Ca(2+)-load were increased, whereas PKA inhibition reduced Ca(2+)-transient amplitude and load and additionally slowed Ca(2+) elimination. In atrial CMs from patients with atrial fibrillation, inhibition of late INa, CaMKII, or PKA reduced the SR-Ca(2+)-leak.CONCLUSION: Late INa exerts distinct effects on Ca(2+) homeostasis in atrial myocardium through activation of CaMKII and PKA. Inhibition of late INa represents a potential approach to attenuate CaMKII activation and decreases SR-Ca(2+)-leak in atrial rhythm disorders. The interconnection with the cAMP/PKA system further increases the antiarrhythmic potential of late INa inhibition.
AB - AIMS: Enhanced cardiac late Na current (late INa) and increased sarcoplasmic reticulum (SR)-Ca(2+)-leak are both highly arrhythmogenic. This study seeks to identify signalling pathways interconnecting late INa and SR-Ca(2+)-leak in atrial cardiomyocytes (CMs).METHODS AND RESULTS: In murine atrial CMs, SR-Ca(2+)-leak was increased by the late INa enhancer Anemonia sulcata toxin II (ATX-II). An inhibition of Ca(2+)/calmodulin-dependent protein kinase II (Autocamide-2-related inhibitory peptide), protein kinase A (H89), or late INa (Ranolazine or Tetrodotoxin) all prevented ATX-II-dependent SR-Ca(2+)-leak. The SR-Ca(2+)-leak induction by ATX-II was not detected when either the Na(+)/Ca(2+) exchanger was inhibited (KBR) or in CaMKIIδc-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 INa-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 INa did not alter Ca(2+)-transient amplitude or SR-Ca(2+)-load. However, upon late INa activation and simultaneous CaMKII inhibition, Ca(2+)-transient amplitude and SR-Ca(2+)-load were increased, whereas PKA inhibition reduced Ca(2+)-transient amplitude and load and additionally slowed Ca(2+) elimination. In atrial CMs from patients with atrial fibrillation, inhibition of late INa, CaMKII, or PKA reduced the SR-Ca(2+)-leak.CONCLUSION: Late INa exerts distinct effects on Ca(2+) homeostasis in atrial myocardium through activation of CaMKII and PKA. Inhibition of late INa represents a potential approach to attenuate CaMKII activation and decreases SR-Ca(2+)-leak in atrial rhythm disorders. The interconnection with the cAMP/PKA system further increases the antiarrhythmic potential of late INa inhibition.
U2 - 10.1093/cvr/cvv153
DO - 10.1093/cvr/cvv153
M3 - SCORING: Journal article
C2 - 25990311
VL - 107
SP - 184
EP - 196
JO - CARDIOVASC RES
JF - CARDIOVASC RES
SN - 0008-6363
IS - 1
ER -