The aims of the present study are to investigate the effect of vasoconstriction and to explore the mechanism of rutae- carpine. The research findings showed that rutaecarpine could induce contractions of the rat thoracic aorta in vitro. The inhibitors of Rho-kinase and inositol 1,4,5-triphosphate receptor （IP 3 R） could suppress the effect of rutaecarpine-induced vasoconstriction. In the study of A7r5 cells （a line of smooth muscle cells）, 300 μg/L rutaecarpine promoted the concentration of intracellular Ca 2＋ and enhanced the IP 3 R expression, which connects with 1,4,5-triphosphate to evoke the release of Ca 2＋ from the intracellular stores. Rutaecarpine increased the RhoA mRNA expression when the cells were pretreated with inhibitor H-1152, and improved the levels of phosphorylation of myosin light chain phosphatase （MLCP） and myosin light chain （MLC）. These results suggest that rutaecarpine plays a role in vasoconstriction relative to the RhoA/MLCP-MLC signaling pathway, which denotes a new field of rutaecarpine in pharmacology.
