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In heart failure and atrial fibrillation, a persistent Na[sup.+] current (I[sub.NaL]) exerts detrimental effects on cellular electrophysiology and can induce arrhythmias. We have recently shown that Na[sub.V]1.8 contributes to arrhythmogenesis by inducing a I[sub.NaL]. Genome-wide association studies indicate that mutations in the SCN10A gene (Na[sub.V]1.8) are associated with increased risk for arrhythmias, Brugada syndrome, and sudden cardiac death. However, the mediation of these Na[sub.V]1.8-related effects, whether through cardiac ganglia or cardiomyocytes, is still a subject of controversial discussion. We used CRISPR/Cas9 technology to generate homozygous atrial SCN10A-KO-iPSC-CMs. Ruptured-patch whole-cell patch-clamp was used to measure the I[sub.NaL] and action potential duration. Ca[sup.2+] measurements (Fluo 4-AM) were performed to analyze proarrhythmogenic diastolic SR Ca[sup.2+] leak. The I[sub.NaL] was significantly reduced in atrial SCN10A KO CMs as well as after specific pharmacological inhibition of Na[sub.V]1.8. No effects on atrial APD[sub.90] were detected in any groups. Both SCN10A KO and specific blockers of Na[sub.V]1.8 led to decreased Ca[sup.2+] spark frequency and a significant reduction of arrhythmogenic Ca[sup.2+] waves. Our experiments demonstrate that Na[sub.V]1.8 contributes to I[sub.NaL] formation in human atrial CMs and that Na[sub.V]1.8 inhibition modulates proarrhythmogenic triggers in human atrial CMs and therefore Na[sub.V]1.8 could be a new target for antiarrhythmic strategies.

In heart failure and atrial fibrillation, a persistent Na+ current (INaL) exerts detrimental effects on cellular electrophysiology and can induce arrhythmias. We have recently shown that NaV1.8 contributes to arrhythmogenesis by inducing a INaL. Genome-wide association studies indicate that mutations in the SCN10A gene (NaV1.8) are associated with increased risk for arrhythmias, Brugada syndrome, and sudden cardiac death. However, the mediation of these NaV1.8-related effects, whether through cardiac ganglia or cardiomyocytes, is still a subject of controversial discussion. We used CRISPR/Cas9 technology to generate homozygous atrial SCN10A-KO-iPSC-CMs. Ruptured-patch whole-cell patch-clamp was used to measure the INaL and action potential duration. Ca2+ measurements (Fluo 4-AM) were performed to analyze proarrhythmogenic diastolic SR Ca2+ leak. The INaL was significantly reduced in atrial SCN10A KO CMs as well as after specific pharmacological inhibition of NaV1.8. No effects on atrial APD90 were detected in any groups. Both SCN10A KO and specific blockers of NaV1.8 led to decreased Ca2+ spark frequency and a significant reduction of arrhythmogenic Ca2+ waves. Our experiments demonstrate that NaV1.8 contributes to INaL formation in human atrial CMs and that NaV1.8 inhibition modulates proarrhythmogenic triggers in human atrial CMs and therefore NaV1.8 could be a new target for antiarrhythmic strategies.

The sodium channel Na[sub.V]1.8, encoded by the SCN10A gene, has recently emerged as a potential regulator of cardiac electrophysiology. We have previously shown that Na[sub.V]1.8 contributes to arrhythmogenesis by inducing a persistent Na[sup.+] current (late Na[sup.+] current, I[sub.NaL]) in human atrial and ventricular cardiomyocytes (CM). We now aim to further investigate the contribution of Na[sub.V]1.8 to human ventricular arrhythmogenesis at the CM-specific level using pharmacological inhibition as well as a genetic knockout (KO) of SCN10A in induced pluripotent stem cell CM (iPSC-CM). In functional voltage-clamp experiments, we demonstrate that I[sub.NaL] was significantly reduced in ventricular SCN10A-KO iPSC-CM and in control CM after a specific pharmacological inhibition of Na[sub.V]1.8. In contrast, we did not find any effects on ventricular APD[sub.90]. The frequency of spontaneous sarcoplasmic reticulum Ca[sup.2+] sparks and waves were reduced in SCN10A-KO iPSC-CM and control cells following the pharmacological inhibition of Na[sub.V]1.8. We further analyzed potential triggers of arrhythmias and found reduced delayed afterdepolarizations (DAD) in SCN10A-KO iPSC-CM and after the specific inhibition of Na[sub.V]1.8 in control cells. In conclusion, we show that Na[sub.V]1.8-induced I[sub.NaL] primarily impacts arrhythmogenesis at a subcellular level, with minimal effects on systolic cellular Ca[sup.2+] release. The inhibition or knockout of Na[sub.V]1.8 diminishes proarrhythmic triggers in ventricular CM. In conjunction with our previously published results, this work confirms Na[sub.V]1.8 as a proarrhythmic target that may be useful in an anti-arrhythmic therapeutic strategy.

The sodium channel NaV1.8, encoded by the SCN10A gene, has recently emerged as a potential regulator of cardiac electrophysiology. We have previously shown that NaV1.8 contributes to arrhythmogenesis by inducing a persistent Na+ current (late Na+ current, INaL) in human atrial and ventricular cardiomyocytes (CM). We now aim to further investigate the contribution of NaV1.8 to human ventricular arrhythmogenesis at the CM-specific level using pharmacological inhibition as well as a genetic knockout (KO) of SCN10A in induced pluripotent stem cell CM (iPSC-CM). In functional voltage-clamp experiments, we demonstrate that INaL was significantly reduced in ventricular SCN10A-KO iPSC-CM and in control CM after a specific pharmacological inhibition of NaV1.8. In contrast, we did not find any effects on ventricular APD90. The frequency of spontaneous sarcoplasmic reticulum Ca2+ sparks and waves were reduced in SCN10A-KO iPSC-CM and control cells following the pharmacological inhibition of NaV1.8. We further analyzed potential triggers of arrhythmias and found reduced delayed afterdepolarizations (DAD) in SCN10A-KO iPSC-CM and after the specific inhibition of NaV1.8 in control cells. In conclusion, we show that NaV1.8-induced INaL primarily impacts arrhythmogenesis at a subcellular level, with minimal effects on systolic cellular Ca2+ release. The inhibition or knockout of NaV1.8 diminishes proarrhythmic triggers in ventricular CM. In conjunction with our previously published results, this work confirms NaV1.8 as a proarrhythmic target that may be useful in an anti-arrhythmic therapeutic strategy.

The effects and mechanisms of cardiac arrhythmias are still incompletely understood and an important subject of cardiovascular research. A major difficulty for investigating arrhythmias is the lack of appropriate human models. Here, we present a protocol for a translational simulation of different types of arrhythmias using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and electric cell culture pacing. The protocol comprises the handling of ventricular and atrial hiPSC-CM before and during in vitro arrhythmia simulation and possible arrhythmia simulation protocols mimicking clinical arrhythmias like atrial fibrillation. Isolated or confluent hiPSC-CM can be used for the simulation. In vitro arrhythmia simulation did not impair cell viability of hiPSC-CM and could reproduce arrhythmia associated phenotypes of patients. The use of hiPSC-CM enables patient-specific studies of arrhythmias, genetic interventions, or drug-screening. Thus, the in vitro arrhythmia simulation protocol may offer a versatile tool for translational studies on the mechanisms and treatment options of cardiac arrhythmias.

Pharmacologic approaches for the treatment of atrial arrhythmias are limited due to side effects and low efficacy. Thus, the identification of new antiarrhythmic targets is of clinical interest. Recent genome studies suggested an involvement of SCN10A sodium channels (NaV1.8) in atrial electrophysiology. This study investigated the role and involvement of NaV1.8 (SCN10A) in arrhythmia generation in the human atria and in mice lacking NaV1.8. NaV1.8 mRNA and protein were detected in human atrial myocardium at a significant higher level compared to ventricular myocardium. Expression of NaV1.8 and NaV1.5 did not differ between myocardium from patients with atrial fibrillation and sinus rhythm. To determine the electrophysiological role of NaV1.8, we investigated isolated human atrial cardiomyocytes from patients with sinus rhythm stimulated with isoproterenol. Inhibition of NaV1.8 by A-803467 or PF-01247324 showed no effects on the human atrial action potential. However, we found that NaV1.8 significantly contributes to late Na+ current and consequently to an increased proarrhythmogenic diastolic sarcoplasmic reticulum Ca2+ leak in human atrial cardiomyocytes. Selective pharmacological inhibition of NaV1.8 potently reduced late Na+ current, proarrhythmic diastolic Ca2+ release, delayed afterdepolarizations as well as spontaneous action potentials. These findings could be confirmed in murine atrial cardiomyocytes from wild-type mice and also compared to SCN10A−/− mice (genetic ablation of NaV1.8). Pharmacological NaV1.8 inhibition showed no effects in SCN10A−/− mice. Importantly, in vivo experiments in SCN10A−/− mice showed that genetic ablation of NaV1.8 protects against atrial fibrillation induction. This study demonstrates that NaV1.8 is expressed in the murine and human atria and contributes to late Na+ current generation and cellular arrhythmogenesis. Blocking NaV1.8 selectively counteracts this pathomechanism and protects against atrial arrhythmias. Thus, our translational study reveals a new selective therapeutic target for treating atrial arrhythmias.

In heart failure and atrial fibrillation, a persistent Na current (I ) exerts detrimental effects on cellular electrophysiology and can induce arrhythmias. We have recently shown that Na 1.8 contributes to arrhythmogenesis by inducing a I . Genome-wide association studies indicate that mutations in the gene (Na 1.8) are associated with increased risk for arrhythmias, Brugada syndrome, and sudden cardiac death. However, the mediation of these Na 1.8-related effects, whether through cardiac ganglia or cardiomyocytes, is still a subject of controversial discussion. We used CRISPR/Cas9 technology to generate homozygous atrial -KO-iPSC-CMs. Ruptured-patch whole-cell patch-clamp was used to measure the I and action potential duration. Ca measurements (Fluo 4-AM) were performed to analyze proarrhythmogenic diastolic SR Ca leak. The I was significantly reduced in atrial KO CMs as well as after specific pharmacological inhibition of Na 1.8. No effects on atrial APD were detected in any groups. Both KO and specific blockers of Na 1.8 led to decreased Ca spark frequency and a significant reduction of arrhythmogenic Ca waves. Our experiments demonstrate that Na 1.8 contributes to I formation in human atrial CMs and that Na 1.8 inhibition modulates proarrhythmogenic triggers in human atrial CMs and therefore Na 1.8 could be a new target for antiarrhythmic strategies.

The sodium channel Na 1.8, encoded by the gene, has recently emerged as a potential regulator of cardiac electrophysiology. We have previously shown that Na 1.8 contributes to arrhythmogenesis by inducing a persistent Na current (late Na current, I ) in human atrial and ventricular cardiomyocytes (CM). We now aim to further investigate the contribution of Na 1.8 to human ventricular arrhythmogenesis at the CM-specific level using pharmacological inhibition as well as a genetic knockout (KO) of in induced pluripotent stem cell CM (iPSC-CM). In functional voltage-clamp experiments, we demonstrate that I was significantly reduced in ventricular -KO iPSC-CM and in control CM after a specific pharmacological inhibition of Na 1.8. In contrast, we did not find any effects on ventricular APD . The frequency of spontaneous sarcoplasmic reticulum Ca sparks and waves were reduced in KO iPSC-CM and control cells following the pharmacological inhibition of Na 1.8. We further analyzed potential triggers of arrhythmias and found reduced delayed afterdepolarizations (DAD) in KO iPSC-CM and after the specific inhibition of Na 1.8 in control cells. In conclusion, we show that Na 1.8-induced I primarily impacts arrhythmogenesis at a subcellular level, with minimal effects on systolic cellular Ca release. The inhibition or knockout of Na 1.8 diminishes proarrhythmic triggers in ventricular CM. In conjunction with our previously published results, this work confirms Na 1.8 as a proarrhythmic target that may be useful in an anti-arrhythmic therapeutic strategy.

Technological innovations are changing mechanisation in agriculture. The most recent wave of innovations referred to as smart farming technologies (SFT), promise to improve farming by responding to economic, ecological, and social challenges and thereby sustainably develop agriculture throughout Europe. To better understand the relevance of ongoing technological progress for farming systems across Europe, 287 farmers were surveyed in 7 EU countries and in 4 cropping systems, alongside 22 in-depth semi-structured interviews with experts from the agricultural knowledge and innovation system. Of the surveyed farmers, about 50% were SFT adopters and 50% were non-adopters. The number of adopters increased with farm size, and there were more adopters among arable cropping systems than in tree crops. Although all farmers broadly perceive SFT as useful to farming and generally expect SFT to continue to be so, when it comes to specific on-farm challenges, farmers are less convinced of SFT potential. Moreover, farmers’ perceptions of SFT vary according to SFT characteristics and farming context. Interestingly, both adopter and non-adopter groups are hesitant regarding SFT adoption, such that adopters are somewhat disillusioned about the SFT that they have experience with, and non-adopters because they are not convinced that the appropriate technologies are available and accessible. About 60% of all farmers surveyed have a number of suggestions for SFT to become more relevant to a broader range of farms. Both farmers and experts generally consider peer-to-peer communication as important sources of information and deplore a lack of impartial advice. Experts are generally more convinced of SFT advantages, and are positive regarding the long-term trends of technological development. The findings support previous findings on using farmers’ perceptions in innovation processes, and provide insight to the recent trends regarding SFT application to diverse cropping systems across Europe. This suggests that differences related to agricultural structures and farming systems across Europe have to be considered if SFT development and dissemination should be improved.

Maintaining or restoring landscape multifunctionality is essential to ensuring that landscapes provide a broad array of services. Increased multifunctionality means that there are more diverse land uses bordering each other. The areas in which land uses interact are transition zones; those between grasslands and forests could fulfill multiple purposes due to their special ecological characteristics that support the needs of diverse species. However, with their management practices, local land users often shape the characteristics of land-use transition zones, with implications for ecological processes that build the base for service provision. Local ecological knowledge of land users could give important insights into the basis of their decisions. Here, we explore how land users’ and farmers’ local knowledge shapes their management that contributes to the maintenance and restoration of multifunctional landscapes. We conducted 21 semistructured qualitative interviews with livestock farmers and local experts for agriculture and nature conservation using grassland–forest transition zones as a specific example for interdependent components of multifunctional landscapes. We found that local knowledge of the interviewed farmers can contribute to the maintenance or restoration of multifunctional landscapes in several ways: it provides insight into landscape functions in grassland–forest transition zones, it enables land users to use landscape function-grassland production synergies, and it provides insight into the perceived negative and positive contributions of forests to grassland production. The perceived negative contributions of forests to grassland production were an important driver for farmers’ management decisions. Farmers have a holistic view of both the field and the landscape. Managing landscapes for multifunctionality is dependent on this kind of holistic knowledge to identify synergies and trade-offs in landscape functions and how they contribute to agricultural production. However, current regulations such as the institutional separation of grassland and forest and grassland area-dependent direct payments prevent farmers from acting according to their local knowledge.