Dataset Information

A Distinct Pool of Na_v1.5 Channels at the Lateral Membrane of Murine Ventricular Cardiomyocytes.

ABSTRACT: Background: In cardiac ventricular muscle cells, the presence of voltage-gated sodium channels Na_v1.5 at the lateral membrane depends in part on the interaction between the dystrophin-syntrophin complex and the Na_v1.5 C-terminal PDZ-domain-binding sequence Ser-Ile-Val (SIV motif). ?1-Syntrophin, a PDZ-domain adaptor protein, mediates the interaction between Na_v1.5 and dystrophin at the lateral membrane of cardiac cells. Using the cell-attached patch-clamp approach on cardiomyocytes expressing Na_v1.5 in which the SIV motif is deleted (?SIV), sodium current (I_Na) recordings from the lateral membrane revealed a SIV-motif-independent I_Na. Since immunostaining has suggested that Na_v1.5 is expressed in transverse (T-) tubules, this remaining I_Na might be carried by channels in the T-tubules. Of note, a recent study using heterologous expression systems showed that ?1-syntrophin also interacts with the Na_v1.5 N-terminus, which may explain the SIV-motif independent I_Na at the lateral membrane of cardiomyocytes. Aim: To address the role of ?1-syntrophin in regulating the I_Na at the lateral membrane of cardiac cells. Methods and Results: Patch-clamp experiments in cell-attached configuration were performed on the lateral membranes of wild-type, ?1-syntrophin knockdown, and ?SIV ventricular mouse cardiomyocytes. Compared to wild-type, a reduction of the lateral I_Na was observed in myocytes from ?1-syntrophin knockdown hearts. Similar to ?SIV myocytes, a remaining I_Na was still recorded. In addition, cell-attached I_Na recordings from lateral membrane did not differ significantly between non-detubulated and detubulated ?SIV cardiomyocytes. Lastly, we obtained evidence suggesting that cell-attached patch-clamp experiments on the lateral membrane cannot record currents carried by channels in T-tubules such as calcium channels. Conclusion: Altogether, these results suggest the presence of a sub-pool of sodium channels at the lateral membrane of cardiomyocytes that is independent of ?1-syntrophin and the PDZ-binding motif of Na_v1.5, located in membrane domains outside of T-tubules. The question of a T-tubular pool of Na_v1.5 channels, however, remains open.

SUBMITTER: Rougier JS

PROVIDER: S-EPMC6619393 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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A Distinct Pool of Nav1.5 Channels at the Lateral Membrane of Murine Ventricular Cardiomyocytes.

Rougier Jean-Sébastien JS Essers Maria C MC Gillet Ludovic L Guichard Sabrina S Sonntag Stephan S Shmerling Doron D Abriel Hugues H

Frontiers in physiology 20190703

Background: In cardiac ventricular muscle cells, the presence of voltage-gated sodium channels Nav1.5 at the lateral membrane depends in part on the interaction between the dystrophin-syntrophin complex and the Nav1.5 C-terminal PDZ-domain-binding sequence Ser-Ile-Val (SIV motif). α1-Syntrophin, a PDZ-domain adaptor protein, mediates the interaction between Nav1.5 and dystrophin at the lateral membrane of cardiac cells. Using the cell-attached patch-clamp ...[more]

PMID: 31333492

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Project description:Infarcted myocardium is predisposed to cause lethal ventricular arrhythmias that remain the main cause of death in patients suffering myocardial ischemia. Liver-derived fibroblast growth factor 21 (FGF21) is an endocrine regulator, which exerts metabolic actions by favoring glucose and lipids metabolism. Emerging evidence has shown a beneficial effect of FGF21 on cardiovascular diseases, but the role of FGF21 on ventricular arrhythmias following myocardial infarction (MI) in humans has never been addressed. This study was conducted to investigate the pharmacological effects of FGF21 on cardiomyocytes after MI in humans. Patients with arrhythmia in acute MI and healthy volunteers were enrolled in this study. Serum samples were collected from these subjects on day 1 and days 7-10 after the onset of MI for measuring FGF21 levels using ELISA. Here, we found that the serum level of FGF21 was significantly increased on day 1 after the onset of MI and it returned to normal on days 7-10, relative to the Control samples. In order to clarify the regulation of FGF21 on arrhythmia, two kinds of arrhythmia animal models were established in this study, including ischemic arrhythmia model (MI rat model) and nonischemic arrhythmia model (ouabain-induced guinea pig arrhythmia model). The results showed that the incidence and duration time of ischemic arrhythmias in rhbFGF21-treated MI rats were significantly reduced at different time point after MI compared with normal saline-treated MI rats. Moreover, the onset of the first ventricular arrhythmias was delayed and the numbers of VF and maintenance were attenuated by FGF21 compared to the rhbFGF21-untreated group in the ouabain model. Consistently, in vitro study also demonstrated that FGF21 administration was able to shorten action potential duration (APD) in hydrogen peroxide-treated AC16 cells. Mechanically, FGF21 can ameliorate the electrophysiological function of AC16 cells, which is characterized by rescuing the expression and dysfunction of cardiac sodium current (I Na) and inward rectifier potassium (I k1) in AC16 cells induced by hydrogen peroxide. Moreover, the restorative effect of FGF21 on NaV1.5 and Kir2.1 was eliminated when FGF receptors were inhibited. Collectively, FGF21 has the potential role of ameliorating transmembrane ion channels remodeling through the NaV1.5/Kir2.1 pathway by FGF receptors and thus reducing life-threatening postinfarcted arrhythmias, which provides new strategies for antiarrhythmic therapy in clinics.

Dataset Information

A Distinct Pool of Na_v1.5 Channels at the Lateral Membrane of Murine Ventricular Cardiomyocytes.

Publications

A Distinct Pool of Na<sub>v</sub>1.5 Channels at the Lateral Membrane of Murine Ventricular Cardiomyocytes.

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