Taurine And L-carnitine Synergistically Inhibit The Proliferation And Osteoblastic Differentiation Of Vascular Smooth Muscle Cells

Taurine and L-carnitine synergistically inhibit the proliferation and osteoblastic differentiation of vascular smooth muscle cellsObjective:The present study was undertaken to determine whether Taurine and L-carnitine can synergistically regulate vascular smooth muscle cells proliferation and calcification and to examine the possible mechanisms.Methods:VSMCs proliferation was assessed by measuring [3H]thymidine incorporation. Alkaline phosphatase (ALP) activity was determined by using p-nitrophenyl phosphate as substrate. Calcium deposition was determined by atomic absorption spectroscopy. Taurine uptakation by VSMCs was assayed by [3H]taurine incorporation. Western blot was performed to determine the expression levels of taurine transporter protein in VSMCs. RNA interference (shRNA) was used to down-regulate the expression of taurine transporter in VSMCs.Results:Taurine suppressed the proliferation and (3-glycerolphosphate-induced osteoblastic differentiation of VSMCs. L-carnitine alone inhibited VSMCs proliferation without causing toxic effects on the cells, and had no effects on the osteoblastic differentiation or mineralization of VSMCs. L-carnitine and Taurine synergistically inhibited the proliferation and (3-glycerophosphate-induced osteoblastic differentiation of VSMCs. L-camitine stimulated the taurine transporter expression and taurine uptakation in VSMCs. Suppression of taurine transporter expression with shRNA abolished the synergistic action of Taurine and L-carnitine.Conclusion:Taurine and L-carnitine have synergistic inhibitory effects on the proliferation and calcification of VSMCs. The up-regulated taurine transporter expression and taurine uptakation by L-carnitine in VSMCs involve in the synergistic action.