Clin Res Cardiol (2021) DOI DOI https://doi.org/10.1007/s00392-021-01843-w

CaMKIIδ interaction with neuronal sodium channel Nav1.8 contributes to enhanced proarrhythmic late sodium current in failing human and mouse cardiomyocytes

N. Dybkova1, S. Ahmad1, P. Tirilomis1, P. Bengel1, N. Hartmann1, S. Pabel2, L. S. Maier2, K. Streckfuß-Bömeke1, G. Hasenfuß1, S. T. Sossalla2

1Herzzentrum, Klinik für Kardiologie und Pneumologie, Universitätsmedizin Göttingen, Göttingen; 2Klinik und Poliklinik für Innere Med. II, Kardiologie, Universitätsklinikum Regensburg, Regensburg;

In heart failure, enhanced persistent current (INaL) through neuronal sodium channel NaV1.8 may induce influx of Na+ into cardiomyocytes. This can cause Ca2+ influx via the Na+/Ca2+ exchanger leading to increased proarrhythmogenic diastolic sarcoplasmic reticulum (SR) Ca2+ leak. Ca2+ in turn may activate Ca2+/calmodulin-dependent protein kinase IIδ (CaMKIIδ) which can induce INaL augmentation by phosphorylating NaV1.5 channels leading to a vicious cycle between INaL and CaMKIIδ. We hypothesized that augmented proarrhythmogenic INaL is due to interaction and thereby regulation of neuronal sodium channel isoform NaV1.8 with CaMKIIδ in human and mouse cardiomyocytes. Interaction of CaMKIIδ and NaV1.8 was confirmed by co-immunoprecipitation. Whole-cell patch clamp showed a potent reduction of INaL after addition of novel specific Nav1.8 blockers, either A-803467 (30 nmol/L) or PF-01247324 (1 µmol/L) in failing mouse cardiomyocytes overexpressing CaMKIIδc (CaMKIIδc+/T: -109.4±10.6 vs A-803467: -56.9±11.7 and PF-01247324: -69.9±8.6 A*ms*F-1). In failing human cardiomyocytes inhibition of either NaV1.8 or CaMKIIδ (AIP 1 µmol/L) or both together led to a significant and comparable decrease of INaL Furthermore, to confirm the specificity of utilized Nav1.8 blockers and to exclude potential influences of Nav1.8 on peak sodium current (INa) we measured INa properties in mouse cardiomyocytes. Importantly, we observed no difference neither in the peak nor in current inactivation between wild type (WT), WT with PF-01247324 and in mice lacking NaV1.8. Using confocal microscopy we investigated whether inhibition of the NaV1.8-mediated INaL could attenuate the increase of proarrhythmogenic SR Ca2+ spark frequency (CaSpF) caused by overexpression of CaMKIIδ in mice. We observed a significant reduction of CaSpF in both NaV1.8 inhibitor groups (PF-01247324: 0.51±0.08 and A-803467: 0.57±0.08 µm-1s-1) compared to control (1.00±0.13 µm-1s-1). Incubation of human failing cardiomyocytes with either AIP (0.35±0.06 µm-1s-1) or PF-01247324 (0.44±0.11 µm-1s-1), or blocking CaMKIIδ and NaV1.8 together (0.30±0.08µm-1s-1) resulted in significant decrease of CaSpF compared to control (0.89±0.13 µm-1s-1). In conclusion, we show for the first time the interaction of the neuronal sodium channel NaV1.8 with CaMKIIδ in human cardiomyocytes. Moreover, pharmacological inhibition of NaV1.8 caused a reduction of the augmented INaL and spontaneous diastolic SR-Ca2+ release in both failing human and mouse cardiomyocytes. Thus, NaV1.8 and CaMKIIδ interaction seems to play a relevant role for the generation of arrhythmogenic triggers (INaL & spontaneous diastolic SR-Ca2+ release) in both human and mouse cardiomyocytes from failing hearts with increased CaMKIIδ activity.

https://dgk.org/kongress_programme/jt2021/aP253.html