Inhibition of P2X7 receptor mitigates atrial fibrillation susceptibility in isoproterenol-induced rats

Background: Atrial fibrillation (AF) is a common cardiac arrhythmia that is characterized by atrial electrical remodeling. The P2X7 receptor (P2X7R), an ATP-gated ion channel, has been implicated in cardiovascular pathologies; however, its role in atrial electrical remodeling remains unclear. This study investigated whether inhibition of P2X7R could mitigate isoproterenol (ISO)-induced atrial electrical remodeling in rats and explored the underlying mechanisms. Methods: Two gene expression profiles related to AF (GSE79768 and GSE10598) were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened using GEO2R. Mendelian randomization (MR) investigated the causal relationship between P2X7R expression and AF. Enrichment analysis was also conducted. An animal model was established via intraperitoneal injection of ISO for 2 weeks. The rats were divided into three groups: control (CTL), ISO, and ISO + Brilliant Blue G (BBG). Cardiac electrophysiological parameters were assessed using programmed electrical stimulation. Myocardial fibrosis and hypertrophy were evaluated using Sirius Red and Wheat Germ Agglutinin staining, respectively. P2X7R abundance was assessed using immunofluorescence, and relevant proteins were detected by Western blotting. Results: GEO2R and MR analyses indicated a correlation between P2X7R expression and AF. Rats in the ISO group exhibited increased P2X7R levels, abnormal cardiac electrophysiology, altered ion channel protein expression, myocardial hypertrophy, and fibrosis. Enrichment analysis indicated that oxidative stress responses might be involved, and Western blotting showed significantly elevated levels of NOX, CaMKII, and associated proteins. BBG (P2X7R inhibitor) treatment mitigated these effects. Conclusions: P2X7R was associated with AF, and inhibition of P2X7R curbed electrical and structural remodeling in ISO-induced AF, potentially via the NOX/CaMKII pathway.