Tsai Chin-Chuan, Lai Tung-Yuan, Huang Wei-Chan, Liu I-Min, Cheng Juei-Tang
Department of Traditional Medicine, School of Post-Baccalaureate Chinese Medicine, China Medical College, Taichung City 40401, Taiwan.
Life Sci. 2002 Aug 2;71(11):1321-30. doi: 10.1016/s0024-3205(02)01852-0.
Tetramethylpyrazine (TMP) is one of the active principles contained in Ligusticum chuanxiong Hort. (Umbelliferae), a herb that has been widely used to treat vascular disorders in China. In the present study, role of potassium channel in the vasodilatation of TMP was investigated using the effect of potassium channel blocker on TMP induced relaxation in isolated aortic rings from Wistar rats. TMP produced a concentration-dependent relaxation in the aortic rings precontracted with vasopressin or phenylephrine. Similar effect of TMP on vasoconstrictions by phenylephrine and vasopressin, induced through two different receptors, indicating the direct vasodilatation of TMP. Specific inhibitors for potassium channel were used to characterize the role of potassium channel in this action of TMP. Only the inhibitors specific to small conductance calcium-activated potassium (SK(Ca)) channel or ATP-sensitive potassium (K(ATP)) channel inhibited the action of TMP. Also, the TMP-induced relaxation was reversed by the inhibitor of soluble guanylyl cyclase in a way similar to that of K(ATP) channel blockade. The obtained results indicated that vasodilatation induced by TMP is related to the opening of SK(Ca) and K(ATP) channels.
川芎嗪（TMP）是川芎（伞形科）所含的活性成分之一，川芎在中国已被广泛用于治疗血管疾病。在本研究中，利用钾通道阻滞剂对Wistar大鼠离体主动脉环中TMP诱导的舒张作用的影响，研究了钾通道在TMP血管舒张中的作用。TMP对用血管加压素或去氧肾上腺素预收缩的主动脉环产生浓度依赖性舒张作用。TMP对由两种不同受体诱导的去氧肾上腺素和血管加压素引起的血管收缩有类似作用，表明TMP具有直接血管舒张作用。使用钾通道特异性抑制剂来表征钾通道在TMP这一作用中的作用。只有小电导钙激活钾（SK（Ca））通道或ATP敏感性钾（K（ATP））通道的特异性抑制剂能抑制TMP的作用。此外，可溶性鸟苷酸环化酶抑制剂以类似于K（ATP）通道阻断的方式逆转了TMP诱导的舒张作用。所得结果表明，TMP诱导的血管舒张与SK（Ca）和K（ATP）通道的开放有关。
