Blockade of KCa3.1 Attenuates Left Ventricular Remodeling after Experimental Myocardial Infarction.

BACKGROUND/AIMS: After myocardial infarction (MI), cardiac fibrosis greatly contributes to left ventricular remodeling and heart failure. The intermediate-conductance calcium-activated potassium Channel (KCa3.1) has been recently proposed as an attractive target of fibrosis. The present study aimed to detect the effects of KCa3.1 blockade on ventricular remodeling following MI and its potential mechanisms. METHODS: Myocardial expression of KCa3.1 was initially measured in a mouse MI model by Western blot and real time-polymerase chain reaction. Then after treatment with TRAM-34, a highly selective KCa3.1 blocker, heart function and fibrosis were evaluated by echocardiography, histology and immunohistochemistry. Furthermore, the role of KCa3.1 in neonatal mouse cardiac fibroblasts (CFs) stimulated by angiotensin II (Ang II) was tested. RESULTS: Myocardium expressed high level of KCa3.1 after MI. Pharmacological blockade of KCa3.1 channel improved heart function and reduced ventricular dilation and fibrosis. Besides, a lower prevalence of myofibroblasts was found in TRAM-34 treatment group. In vitro studies KCa3.1 was up regulated in CFs induced by Ang II and suppressed by its blocker.KCa3.1 pharmacological blockade attenuated CFs proliferation, differentiation and profibrogenic genes expression and may regulating through AKT and ERK1/2 pathways. CONCLUSION: Blockade of KCa3.1 is able to attenuate ventricular remodeling after MI through inhibiting the pro-fibrotic effects of CFs.

[Effect of Kv1.3 and KCa3.1 potassium ion channels on the proliferation and migration of monocytes/macrophages].

This study was aimed to investigate the effects of blockade of Ca(2+) activated channel KCa3.1 and voltage-gated potassium channel Kv1.3 of the monocytes/macrophages on inflammatory monocyte chemotaxis. Chemotaxis assay was used to test the inflammatory Ly-6C(hi) monocyte chemotaxis caused by the monocytes/macrophages. The proliferation of monocytes/macrophages was detected by cell counting kit-8 (CCK8). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the C-C motif ligand 7 (CCL7) in cultured media. The results showed that the recruitment of Ly-6C(hi) monocyte induced by monocytes/macrophages was suppressed by the potent Kv1.3 blocker Stichodactyla helianthus neurotoxin (ShK) or the specific KCa3.1 inhibitor TRAM-34. Meanwhile, the proliferation of monocytes/macrophages was significantly inhibited by ShK. The response of Ly-6C(hi) monocyte pretreated with ShK or TRAM-34 to CCL2 was declined. These results suggest that KCa3.1 and Kv1.3 may play an important role in monocytes/macrophages' proliferation and migration.