During atrial fibrillation (AF), electrical remodeling occurs, involving ion channels like NaV1.5, KV1.5, and TASK-1. A promising AF treatment encompasses inhibiting these channels. In this study, acetamide compounds were designed based on the local anesthetic pharmacophore as potential NaV1.5, KV1.5, and TASK-1 inhibitors. Compound 6f emerged as the most potent in the series, with IC50 values determined in Xenopus oocytes of approximately 0.3 µM in TASK-1, 81.5 µM in KV1.5, and 21.2 µM in NaV1.5. Unexpectedly, 6f activated at 100 µM another cardiac K2P channel (TASK-4) by about 40%. Next, we performed patch clamp experiments of human atrial cardiomyocytes from sinus rhythm (SR) or AF patients. In SR 6f reduced action potential amplitude (indicating NaV1.5 block) while in AF it increased action potential duration (APD), reflecting high affinity for TASK-1. Additionally, a hyperpolarization in resting membrane potential occurred in AF cardiomyocytes by 6f, consistent with the TASK-4 activation we observed. In a mathematical whole-atria model, 6f prolonged APD and tissue refractoriness, proving efficacious both for AF prevention and cardioversion. Favorable pharmacokinetic properties of 6f in silico, including good absorption and low toxicity, as well as its lack of cytotoxicity in a hemolytic assay, suggest its potential as an AF treatment.

Advances in different technological and scientific fields have led to the development of tools that allow the design of drugs in a rational way, using defined therapeutic targets, and through simulations that offer a molecular view of the ligand–receptor interactions, giving precise information for the design and synthesis of new compounds. Ion channels are of great relevance as therapeutic targets since they play roles in different pathologies. Several ion channels are expressed in the atria and constitute a therapeutic target for the treatment of atrial fibrillation (AF), the most common type of arrhythmia and an important risk factor for an increase in cerebrovascular illness. The action potential (AP) of a cardiomyocyte is initiated by the depolarization of the membrane through the inflow of sodium (Na⁺). The repolarization currents are realized by different potassium (K⁺) channels. Background currents of TASK-1 channels can also contribute to AP, and TASK-1 channel blockers could become innovative strategies against AF. The compounds used in this study were based on local anesthetic (LAs)-type compounds that have been shown to be TASK-1 channel blockers, such as lidocaine, ropivacaine, and bupivacaine, and that have antiarrhythmic capacity, becoming potentially effective drugs for the treatment of AF. The main objective of this study was, based on the common characteristics of LAs, to propose the synthesis of analogues of LAs and evaluate them in silico as TASK-1 channel blockers.