KCa3.1 Promotes the Migration of Macrophages From Epicardial Adipose Tissue to Induce Vulnerability to Atrial Fibrillation During Rapid Pacing

The relationship between local epicardial adipose tissue (EAT) macrophages and atrial fibrillation (AF) remains unclear. The purpose of this study was to investigate the role of KCa3.1 in the migration of macrophages from EAT to adjacent atrial tissue during rapid pacing. Part 1: Eighteen beagles were randomly divided into the sham group, pacing group, and pacing + clodronate liposome (CL) group. Part 2: Eighteen beagles were randomly divided into the sham group, pacing group, and pacing + TRAM-34 group. HL-1 cells and RAW264.7 cells were co-cultured to explore the specific migratory mechanism of macrophages. Depleting EAT macrophages significantly reduced macrophage infiltration in the adjacent atrium and the induction of AF in canines with rapid atrial pacing. TRAM-34 significantly inhibited the migration of macrophages from EAT to the adjacent atrium and electrical remodelling in canines with rapid atrial pacing. Compared with those of the control HL-1 cells, the secretion of CCL2 and the number of migrating macrophages in pacing HL-1 cells was significantly increased, which could be reversed by TRAM-34. Further in vitro experiments showed that KCa3.1 regulated CCL2 secretion through the p65/STAT3 signalling pathway. Inhibiting myocardial KCa3.1 reduced the migration of EAT macrophages to adjacent atrial muscles caused by rapid atrial pacing, thereby decreasing vulnerability to AF. The mechanism by which KCa3.1 regulates CCL2 may be related to the p65/STAT3 signalling pathway.