Inhibition of late sodium current via PI3K/Akt signaling prevents cellular remodeling in tachypacing-induced HL-1 atrial myocytes

Abstract

An aberrant late sodium current (INa,Late) caused by a mutation in the cardiac sodium channel (Nav1.5) has emerged as a contributor to electrical remodeling that causes susceptibility to atrial fibrillation (AF). Although downregulation of phosphoinositide 3-kinase (PI3K)/Akt signaling is associated with AF, the molecular mechanisms underlying the negative regulation of INa,Late in AF remain unclear, and potential therapeutic approaches are needed. In this work, we constructed a tachypacing-induced cellular model of AF by exposing HL-1 myocytes to rapid electrical stimulation (1.5 V/cm, 4 ms, 10 Hz) for 6 h. Then, we gathered data using confocal Ca2+ imaging, immunofluorescence, patch-clamp recordings, and immunoblots. The tachypacing cells displayed irregular Ca2+ release, delayed afterdepolarization, prolonged action potential duration, and reduced PI3K/Akt signaling compared with controls. Those detrimental effects were related to increased INa,Late and were significantly mediated by treatment with the INa,Late blocker ranolazine. Furthermore, decreased PI3K/Akt signaling via PI3K inhibition increased INa,Late and subsequent aberrant myocyte excitability, which were abolished by INa,Late inhibition, suggesting that PI3K/Akt signaling is responsible for regulating pathogenic INa,Late. These results indicate that PI3K/Akt signaling is critical for regulating INa,Late and electrical remodeling, supporting the use of PI3K/Akt-mediated INa,Late as a therapeutic target for AF.

Resveratrol mediates mitochondrial function through the sirtuin 3 pathway to improve abnormal metabolic remodeling in atrial fibrillation

“…We first established the HL-1 atrial muscle cells by exposing to rapid electrical stimulation to construct a cellular AF model, according to previous published study. 22 The CCK-8 results demonstrated that cell viability remained stable for 24 h in the control group, whereas it gradually decreased in the AF group ( p <0.05) ( Figure 1A ). To initially explore the effect of resveratrol on the AF cell model, we used resveratrol at different concentration gradients (0, 0.1, 1, 10, and 50 μmol/L) to treat HL-1 cells for stimulation induction and then pacemaker treatment.…”

“… 28-31 Studies have pointed out that reduced ATP levels, loss of mitochondrial membrane potential and fragmentation of the mitochondrial network can lead to contractile dysfunction and progression of AF in clinical and experimental studies. 22 Other studies have also shown that Ca 2+ overload is closely related to mitochondrial function. Mitochondria are one of the main storage sites of calcium ions in cells.…”

“…The needed cell capture efficiency for the entire stimulation period was 90% (confirmed by microscopy and shortened duration of action potentials). 22 …”

Dissecting the Molecular Mechanisms Driving Electropathology in Atrial Fibrillation: Deployment of RNA Sequencing and Transcriptomic Analyses

“…Upregulated genes were enriched in focal adhesion, MAPK signaling, RAP1 signaling, PI3KT signaling and cardiac muscle contraction pathways. The first pathway is associated with AF-related fibrosis and the latter three are connected to electrical remodeling in AF [ 31 , 32 , 33 , 34 ]. Chen et al and Jiang et al compared gene expression levels of RA tissue from SR patients with both the RA and LA tissues from PeAF patients [ 15 , 16 ].…”