Magnesium inhibits β-glycerophosphate-induced calcification of vascular smooth muscle cells by L-type calcium channel α1C and β3 in rats

Abstract

Objective To explore the effects of L-type calcium channel (LTCC) α1C and β3 subunits on that magnesium inhibited thoracic aortic calcification induced by β-glycerophosphate (β-GP). Methods Vascular smooth muscle cells (VSMCs) and aortic rings from rat aortic were cultured, then divided into control group, high phosphorus group (10 mmol/L β-GP), magnesium group (10 mmol/L β-GP+ 3 mmol/L MgSO4) and 2-APB (an inhibitor of magnesium transporter) group (10 mmol/L β-GP+3 mmol/L MgSO4+0.1 mmol/L 2-APB). Calcium deposition of VSMCs and aortic rings were respectively measured by alizarin red staining and Von Kossa staining, meanwhile the quantification of their calcium was tested by OCPC. The mRNA expressions of Runx2, LTCC α1C and β3 in VSMCs were detected by RT-PCR, and their protein expressions were detected by Western blotting. Intracellular calcium ion of VSMCs was tested by fluorescence probe and alkaline phosphatase (ALP) activity was measured by ELISA. The Runx2 expression of aortic rings was detected by immunohistochemistry. Results After VSMCs stimulated for 7 days, calcium, ALP, mRNA and protein expressions of LTCCα1C, LTCCβ3 and Runx2, and intracellular calcium ion in high phosphorus group were higher than those in control group (all P 0.05). Conclusion Magnesium may down-regulate expressions of LTCC α1C and β3 subunit, prevent calcium influx and then inhibit osteogenic differentiation so as to reduce β-glycerophosphate-induced VSMCs calcification. Key words: Magnesium; Myocytes, smooth muscle; Calcinosis; Calcium channels, L-type