Abstract: Abstract：Objective To explore the?effect of different?pH on calcification of rat vascular smooth muscle cells (VSMCs) through the bone morphogenetic protein2 (BMP-2) signaling pathway. Methods Healthy male SD rats aged?5-8-weeks were selected in the study.?VSMCs?from rat thoracic?aorta?were cultured?invitro,?and then identified?by?immunocytochemistry.?The?VSMCs?were randomly?divided into?4 groups by random sampling method: normal group(pH7.4), pH7.4+high phosphorus group, pH7.1+high phosphorus group, and pH7.7+high phosphorus group.Calcium deposition and ALP activity were measured by Alizarin red staining, quantification of calcium and enzyme linked immunosorbent assay.The of BMP-2, Smad1, Runx2 mRNA was detected by RT-PCR .Results Compared with the control group, the pH7.4+ high phosphorus group calcification staining, calcium content, alkaline phosphatase (ALP) activity and the of Runx2 mRNA average increased (P<0.05).While compared with the pH7.4+high phosphorus group, the pH7.1+high phosphorus group calcification staining, calcium content, alkaline phosphatase (ALP) activity and the of BMP-2, Smad1, Runx2 mRNA average decreased (P<0.05), and the pH7.7+high phosphorus group calcification staining, calcium content, alkaline phosphatase (ALP) activity and the of BMP-2, Smad1, Runx2 mRNA average increased (P<0.05).Conclusion Extracelluar acidic environment(pH7.1) can inhibit high-phosphotus-induced VSMCs calcification,whereas extracelluar alkaline environment(pH7.7) induce high-phosphotus-induced VSMCs calcification.The mechanism is presumably that VSMCs calcification is induced by influencing BMP-2 pathway, which may mediate the transdifferentiation of vascular smooth muscle cells.

Key words: Key words：Vascular smooth muscle cells, Vascular calcification, pH, BMP-2 signaling pathway