Studies on the Calcium Antagonist Action of Arctigenin / 中草药

ABSTRACT

The calcium antagonist action of arctigenin (ACT) was studied in order to verify the ef-fect of Fructus Arctii for the relieve of exterior syndrome. Muscular contraction of isolated rat trachea,colon, pulmonary artery and thoracic aorta induced by KC1, that of guinea pig trachea induced by CaCI2,before and after the addition of ACT were assessed and their contraction-response curves drawn and PD'2calculated according to Scott. The inhibition rate of two-phase contraction of guinea pig trachea induced byacetylcholine chloride (Ach) in comparison with verapamil (VER) was calculated. Results of the studyshowed that ACT could non-compatitively antagonize the muscular contraction of the test specimens withPD'2 of 4.01, 5.11, 5.98 and 6.05 respectively. Similar to VER, ACT could non-competitively antagonizethe isolated guinea pig trachea with PD'2 of 4.04 and 5.62 respectively. Both of them could inhibit thefirst phase contraction induced by Ach with inhibition rates of 66.14% and 81.42% respectively. It wasconcluded that ACT, as the active constituent of Fructus Arctii, relaxed smooth muscle contraction byblocking the potential dependant Ca2+ channel and the internal release of Ca2+.