KCa3.1 Channels Promote Cardiac Fibrosis Through Mediating Inflammation and Differentiation of Monocytes Into Myofibroblasts in Angiotensin II–Treated Rats

Background Cardiac fibrosis is a core pathological process associated with heart failure. The recruitment and differentiation of primitive fibroblast precursor cells of bone marrow origin play a critical role in pathological interstitial cardiac fibrosis. The KCa3.1 channels are expressed in both ventricular fibroblasts and circulating mononuclear cells in rats and are upregulated by angiotensin II. We hypothesized that KCa3.1 channels mediate the inflammatory microenvironment in the heart, promoting the infiltrated bone marrow–derived circulating mononuclear cells to differentiate into myofibroblasts, leading to myocardial fibrosis. Methods and Results We established a cardiac fibrosis model in rats by infusing angiotensin II to evaluate the impact of the specific KCa3.1 channel blocker TRAM‐34 on cardiac fibrosis. At the same time, mouse CD4+ T cells and rat circulating mononuclear cells were separated to investigate the underlying mechanism of the TRAM‐34 anti–cardiac fibrosis effect. TRAM‐34 significa...