Department of Pharmacology, Kyungpook National University School of Medicine, Daegu, 700-422, Republic of Korea.
Environ Toxicol Pharmacol. 2007 Nov;24(3):199-205. doi: 10.1016/j.etap.2007.05.004. Epub 2007 May 24.
Samhwangsasim-tang (SST) is a widely used herbal medicine with vasodilatory actions in oriental countries. We hypothesized that SST modulates vascular contractility by decreasing phosphorylation of the myosin phosphatase target subunit. Rat aortic ring preparations were mounted in organ baths and subjected to contractions or relaxations. Phosphorylation of 20kDa myosin light chains (MLC(20)) and MYPT1, a target subunit of myosin phosphate 1, were examined with immunoblots. SST relaxed aortic ring preparations precontracted with phenylephrine whether endothelium was intact or denuded. Treatment of aortic rings with N(ω)-nitro-l-arginine methyl ester (l-NAME), an inhibitor of endothelial nitric oxide synthase or methylene blue, an inhibitor of guanylyl cyclase, did not affect the relaxing action of SST. Furthermore, SST inhibited vascular contractions induced by NaF or phenylephrine, but not by phorbol dibutyrate. SST also decreased vascular tension precontracted by 8.0mmol/L NaF or 1.0μmol/L phenylephrine, but not by 1.0μmol/L phorbol dibutyrate. In vascular strips, SST decreased the phosphorylation level of both MLC(20) and MYPT1 induced by 8.0mmol/L NaF. In conclusion, SST inhibited vascular contraction by decreasing phosphorylation of the myosin phosphatase target subunit.
三黄泻心汤（SST）是一种在东方国家具有血管扩张作用的常用草药。我们假设 SST 通过降低肌球蛋白磷酸酶靶亚基的磷酸化来调节血管收缩性。将大鼠主动脉环制剂安装在器官浴中，并进行收缩或松弛。用免疫印迹法检查 20kDa 肌球蛋白轻链（MLC（20））和肌球蛋白磷酸酶 1 的靶亚基 MYPT1 的磷酸化。SST 松弛了预先用苯肾上腺素收缩的主动脉环制剂，无论内皮是否完整或剥脱。用内皮型一氧化氮合酶抑制剂 N（ω）-硝基-L-精氨酸甲酯（l-NAME）或鸟苷酸环化酶抑制剂亚甲蓝处理主动脉环，不影响 SST 的舒张作用。此外，SST 抑制了由 NaF 或苯肾上腺素诱导的血管收缩，但不抑制佛波醇二丁酸酯诱导的血管收缩。SST 还降低了由 8.0mmol/L NaF 或 1.0μmol/L 苯肾上腺素预收缩引起的血管张力，但不降低由 1.0μmol/L 佛波醇二丁酸酯预收缩引起的血管张力。在血管条中，SST 降低了由 8.0mmol/L NaF 诱导的 MLC（20）和 MYPT1 的磷酸化水平。总之，SST 通过降低肌球蛋白磷酸酶靶亚基的磷酸化来抑制血管收缩。
