Effect of tetramethylpyrazine on potassium channels to lower calcium concentration in cultured aortic smooth muscle cells

Summary 1. Tetramethylpyrazine (TMP) is one of the active principles contained in Ligusticum chuanxiong Hort. (Umbelliferae), a herb that has been used widely in China to treat vascular disorders. 2. In an attempt to elucidate the possible mechanisms of action of TMP, the effect of TMP on intracellular calcium concentrations ([Ca 2+ ] i ) was investigated in cultured vascular smooth muscle (A7r5) cells using the Ca 2+ ‐sensitive dye Fura‐2 as an...