Effects of three kinds of calcium activator on the proliferation of cultured vascular smooth muscle cells in rats

AIM: To investigate the effects of intracellular free calcium ([Ca²⁺]i) from different resources on the proliferation mediated by mitogen activated protein kinase (MAPK) in vascular smooth muscle cells (VSMCs). METHODS: Cultured VSMCs were used in all experiments. Calcium influx was stimulated by angiotension Ⅱ(Ang Ⅱ). The release of intracellular calcium stores was induced by inositol trisphosphate (IP₃) and ryanodine (RY). MAPK activity was measured by [γ-³²P]-ATP incorporation MAPK protein expression by western blot, VSMCs proliferation by [³H]-Leucine ([³H]-Leu) and [³H]-Thymidine ([³H]-TdR) incorporation. RESULTS: Compared to the control VSMCs, Ang Ⅱ, IP₃ and RY significantly increased [Ca²⁺]i concentration activity of MAPK and its protein content in VSMCs. The promotion of [³H]-Leu and [³H]-TdR incorporation in VSMCs was also observed (P<0.01). CONCLUSION: The study indicated that calcium activator-induced increase in the activity and protein content of MAPK was involved in the proliferation of VSMCs, which was closely related to the [Ca²⁺]i concentration but independent to its origin.