The Arf6/PIP5K pathway activates IKACh in cigarette smoke mediated atrial fibrillation

The Role of KACh Channels in Atrial Fibrillation

This manuscript explores the intricate role of acetylcholine-activated inward rectifier potassium (KACh) channels in the pathogenesis of atrial fibrillation (AF), a common cardiac arrhythmia. It delves into the molecular and cellular mechanisms that underpin AF, emphasizing the vital function of KACh channels in modulating the atrial action potential and facilitating arrhythmogenic conditions. This study underscores the dual nature of KACh activation and its genetic regulation, revealing that specific variations in potassium channel genes, such as Kir3.4 and K2P3.1, significantly influence the electrophysiological remodeling associated with AF. Furthermore, this manuscript identifies the crucial role of the KACh-mediated current, IKACh, in sustaining arrhythmia through facilitating shorter re-entry circuits and stabilizing the re-entrant circuits, particularly in response to vagal nerve stimulation. Experimental findings from animal models, which could not induce AF in the absence of muscarinic activation, highlight the dependency of AF induction on KACh channel activity. This is complemented by discussions on therapeutic interventions, where KACh channel blockers have shown promise in AF management. Additionally, this study discusses the broader implications of KACh channel behavior, including its ubiquitous presence across different cardiac regions and species, contributing to a comprehensive understanding of AF dynamics. The implications of these findings are profound, suggesting that targeting KACh channels might offer new therapeutic avenues for AF treatment, particularly in cases resistant to conventional approaches. By integrating genetic, cellular, and pharmacological perspectives, this manuscript offers a holistic view of the potential mechanisms and therapeutic targets in AF, making a significant contribution to the field of cardiac arrhythmia research.

The impact of lifestyle factors on atrial fibrillation

Atrial fibrillation (AF), with its significant associated morbidity and mortality contributes to significant healthcare utilisation and expenditure. Given its progressively rising incidence, strategies to limit AF development and progression are urgently needed. Lifestyle modification is a potentially potent but underutilised weapon against the AF epidemic. The purpose of this article is to review the role of lifestyle factors as risk factors for AF, outline potential mechanisms of pathogenesis and examine the available evidence for lifestyle intervention in primary and secondary AF prevention. It will also highlight the need for investment by physicians, researchers, health services and governments in order to facilitate delivery of the comprehensive, multidisciplinary AF care that is required to manage this complex and multifactorial disease.

Inhibition of the acetylcholine-regulated potassium current prevents transient apnea-related atrial arrhythmogenic changes in a porcine model

BACKGROUND

More than 50% of patients with atrial fibrillation (AF) suffer from sleep disordered breathing (SDB). Obstructive respiratory events contribute to a transient, vagally mediated atrial arrhythmogenic substrate, which is resistant to most available antiarrhythmic drugs.

OBJECTIVE

The purpose of this study was to investigate the effect of pharmacologic inhibition of the G-protein-gated acetylcholine-regulated potassium current (IK,ACh) with and without acute autonomic nervous system activation by nicotine in a pig model for obstructive respiratory events.

METHODS

In 21 pigs, SDB was simulated by applying an intermittent negative upper airway pressure (INAP). AF inducibility and atrial effective refractory periods (aERPs) were determined before and during INAP by an S1S2 atrial pacing-protocol. Pigs were randomized into 3 groups-group 1: vehicle (n = 4); group 2: XAF-1407 (IK,ACh inhibitor) (n = 7); and group 3: nicotine followed by XAF-1407 (n = 10).

RESULTS

In group 1, INAP shortened aERP (ΔaERP -42.6 ms; P = .004) and transiently increased AF inducibility from 0% to 31%. In group 2, XAF-1407 prolonged aERP by 25.2 ms (P = .005) during normal breathing and prevented INAP-induced aERP shortening (ΔaERP -3.6 ms; P = .3) and AF inducibility. In group 3, INAP transiently shortened aERP during nicotine perfusion (ΔaERP -33.6 ms; P = .004) and increased AF inducibility up to 61%, which both were prevented by XAF-1407.

CONCLUSION

Simulated obstructive respiratory events transiently shorten aERP and increase AF inducibility, which can be prevented by the IK,ACh-inhibitor XAF-1407. XAF-1407 also prevents these arrhythmogenic changes induced by obstructive respiratory events during nicotine perfusion. Whether IK,ACh channels represent a target for SDB-related AF in humans warrants further study.

ADP-ribosylation: An emerging direction for disease treatment

ADP-ribosylation (ADPr) is a dynamically reversible post-translational modification (PTM) driven primarily by ADP-ribosyltransferases (ADPRTs or ARTs), which have ADP-ribosyl transfer activity. ADPr modification is involved in signaling pathways, DNA damage repair, metabolism, immunity, and inflammation. In recent years, several studies have revealed that new targets or treatments for tumors, cardiovascular diseases, neuromuscular diseases and infectious diseases can be explored by regulating ADPr. Here, we review the recent research progress on ART-mediated ADP-ribosylation and the latest findings in the diagnosis and treatment of related diseases.

Lifestyle changes in atrial fibrillation management and intervention

Atrial fibrillation (AF) is one of the most common arrhythmias in adults, and its continued rise in the United States is complicated by the increased incidence and prevalence of several AF risk factors, such as obesity, physical inactivity, hypertension, obstructive sleep apnea, diabetes mellitus, coronary artery disease, and alcohol, tobacco, or caffeine use. Lifestyle and risk factor modification has been proposed as an additional pillar of AF therapy, added to rhythm control, rate control, and anticoagulation, to reduce AF burden and risk. Although emerging evidence largely supports the integration of lifestyle and risk factor management in clinical practice, randomized clinical trials investigating the long-term sustainability and reproducibility of these benefits remain sparse. The purpose of this review is to discuss potentially reversible risk factors on AF, share evidence for the impact on AF by modification of these risk factors, and then provide an overview of the effects of reversing or managing these risk factors on the success of various AF management strategies, such as antithrombotic, rate control, and rhythm control therapies.