对牛蒡苷元（ACT）的钙拮抗作用进行探讨，为确认 ACT是牛蒡子解表功能的有效成分提供实验依据。描记给 ACT前后，各标本对 KCl或 Ca Cl₂ 诱发收缩的量效曲线，按 Scott法计算 PD'2；测定给 ACT后，标本对乙酰胆硷（Ach）诱发的两相收缩的抑制百分率。 ACT对离体大鼠气管、结肠、肺动脉、胸主动脉平滑肌由 KCl引起的收缩产生非竞争性拮抗作用，其 PD'2 分别为4.01，5.11，5.98，6.05；ACT和维拉帕米（Verapamil）相似，对离体豚鼠气管平滑肌由 Ca Cl₂ 引起的收缩产生非竞争性拮抗作用，其 PD'2 分别为4.04，5.62；对 Ach诱发的两相收缩只明显抑制第一时相收缩，抑制率分别为66.14%，81.42 %.ACT对平滑肌的松弛作用可能是由于阻滞电压依赖性钙通道和内钙释放所致；ACT是牛蒡子解表功能的有效成分。

The calcium antag onist actionofarctigenin（ACT）was studied in order toverify the effect of Fructus Arctiifor th e reliev e of ex terior syndrome. Muscular contraction of isolated rat t rachea, colon, pulmona ry a rtery and thoracic aorta induced by KCl, that ofg uinea pig t rachea induced by CaCl₂ , before and af ter the addition of ACT were assessed and their contraction-response curv es drawn and PD'2 calculated according toScott. The inhibition rate of two-phase contractionofguinea pig t rachea induced by acety lcholine chloride（Ach）in comparison with vera pamil（V ER）was calculated. Results of the study showed that ACT couldnon-compa titively antagonize the muscular cont raction of the test specimens withPD'2 of4.01,5.11,5.98 and6.05 respectiv ely. Similar toVER, AC T couldnon-competitiv ely antag onize the isola tedg uinea pig t rachea with PD'2 of 4.04 and 5.62 respectively. Both of them could inhibit the first phase cont raction induced by Ach with inhibition rates of66.14% and81.42% respectively. It was concluded that ACT, as the activ e constituent of Fructus Arctii, relax ed smooth muscle contraction by blocking the potential dependant Ca²⁺channel and the internal release of Ca²⁺.