BK channel agonists may affect matrix vesicle secretion and ameliorate vascular calcification via autophagy.

Abstract

Background: Vascular calcification (VC) is a common high-risk factor for cardiovascular disease and is mainly caused by the deposition of calcium (Ca²⁺), phosphorus, and other minerals on the walls of arteries and veins; however, its specific pathogenic mechanism is still unclear. The aim of the present study was to explore the effect of large-conductance calcium and voltage-activated potassium (BK) channels in regulating VC.

Methods: In this study, primary vascular smooth muscle cells (VSMCs) isolated from the rat or murine thoracic aorta were treated with calcifying media and NS1619 and 3-methyladenine (3-MA) and divided into the following five groups: (I) the control group; (II) the control + NS1619 group; (III) the calcify group; (IV) the calcify + NS1619 group; (V) the calcify + NS1619+3-MA group. Twelve male C57BL/6 mice (20-25 g) were treated with vitamin D and NS1619 and divided into the following four groups: (I) the control group; (II) the vitamin D model group; (III) the vitamin D +5 mg/kg NS1619 group; and (IV) the vitamin D +10 mg/kg NS1619 group. Gene expression, protein expression and the size and concentration of MVs were tested by quantitative polymerase chain reaction (qPCR), Western blot (WB), immunohistochemistry and nanoparticle tracking analysis (NTA), respectively.

Results: We found that BK channels regulate VC. BK channel downregulation was observed in samples from animal and cell models of VC. Both the application of the BK channel agonist NS1619 and BK overexpression modulated the expression of Runt-related transcription factor 2 (Runx2) and alpha-smooth muscle actin (α-SMA) by suppressing matrix vesicles (MVs) formation and secretion, consequently improving VC in VSMCs. However, intervention with the autophagy inhibitor 3-MA appeared to regulate the secretion of MVs and simultaneously weakened the therapeutic effect of NS1619 on calcification.

Conclusions: Although our experimental sample size is small, we still speculate that BK channel agonists might inhibit the secretion of MVs by activating autophagy, thereby alleviating VC. BK channels may be applied in clinical practice and become a potential target for treating VC.