Modulation of calcification of vascular smooth muscle cells in culture by calcium antagonists, statins, and their combination.

Background: Vascular calcification is an organized process in which vascular smooth muscle cells (VSMCs) are implicated primarily. The purpose of the present study was to assess the effects of calcium antagonists and statins on VSMC calcification in vitro.

Methods: VSMC calcification was stimulated by incubation in growth medium supplemented with 10 mmol/l beta-glycerophosphate, 8 mmol/l CaCl(2), 10 mmol/l sodium pyruvate, 1 micromol/l insulin, 50 microg/ml ascorbic acid, and 100 nmol/l dexamethasone (calcification medium). Calcification, proliferation, and apoptosis of VSMCs were quantified.

Results: Calcium deposition was stimulated dose-dependently by beta-glycerophosphate, CaCl(2), and ascorbic acid (all P < 0.01). Addition of amlodipine (0.01-1 micromol/l) to the calcification medium did not affect VSMC calcification. However, atorvastatin (2-50 micromol/l) stimulated calcium deposition dose-dependently. Combining treatments stimulated calcification to a degree similar to that observed with atorvastatin alone. Both atorvastatin and amlodipine inhibited VSMC proliferation at the highest concentration used. Only atorvastatin (50 micromol/l) induced considerable apoptosis of VSMCs.

Conclusion: In vitro calcification of VSMCs is not affected by amlodipine, but is stimulated by atorvastatin at concentrations > or =10 micromol/l, which could contribute to the plaque-stabilizing effect reported for statins.