Abstract: Objective To investigate the effect of high phosphate on calcification of rat vascular smooth muscle cells(VSMCs) and the morphological features of calcified rat's VSMCs under transmission electron microscope. Methods VSMCs from explants of rat aortic media were cultured. Cells were divided into two groups: the normal calcium(Ca) and phosphate group(control group, phosphate 1.4 mmol/L, Ca 2.0 mmol/L), and high phosphate group(phosphate 2.4 mmol/L, Ca 2.0 mmol/L). Calcium deposition of cells were measured by atomic absorptiometry. VSMCs of both groups cultured for 10 days were examined under transmission electron microscope. Results After ten days culture, the calcium deposition in high phosphate group increased significantly(P<0.01). In contrast, there was little calcium deposition in control group. Collagen fibers were found in the extracellular matrix in both groups. Electron-dense calcified deposits were observed on the collagen fibers in high phosphate group. Conclusion This study suggests that elevated phosphate may directly stimulate rat VSMCs to be calcified. Electron-dense calcified deposits were mainly observed on the collagen fibers.

Key words: vascular smooth muscle cells, high phosphate, vascular calcification, transmission electron microscope