Metformin Inhibits Vascular Calcification in Female Rat Aortic Smooth Muscle Cells via the AMPK-eNOS-NO Pathway

Metformin exhibits diverse protective effects against diabetic complications, such as bone loss. Here, we investigated the effect of metformin on vascular calcification, another type 2 diabetes complication. In female rat aortic smooth muscle cells (RASMCs), we observed that metformin significantly alleviated beta-glycerophosphate-induced Ca deposition and alkaline phosphatase activity, corresponding with reduced expression of some specific genes in osteoblast-like cells, including Runx2 and bone morphogenetic protein-2, and positive effects on beta-actin expression, a specific marker of smooth muscle cells. Mechanistic analysis showed that phosphorylation levels of both AMP-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS) were increased with NO overproduction. After inhibition of either AMPK or eNOS with the pharmacologic inhibitors, compound C or N omega-Nitro-L-argininemethyl ester, NO production was lowered and metformin-meditated vascular protection against beta-glycerophosphate-induced Ca deposition was removed. Our results support that metformin prevents vascular calcification via AMPK-eNOS-NO pathway.