Abstract: PA may act as a Ca antagonist to exert an intensively vasorelaxant effects through endothelium-independent pathway, and its mechanisms underlying the vasoactivities seem to be associated with the blockade of extracellular Ca influx through VDCCs and ROCCs in vascular smooth muscle cells (VSMCs) membrane and intracellular Ca releases through IPR- and RYR-mediated Ca channels in sarcolemma.