Abstract:Total coumarins in the fruit of Cnidium monnieri show a marked protective effect against hronchial asthma induced by inhalation of histamine in conscious guinea pig. In vitro these total coumarins can relax the contraction of the isolated trachea in guinea pigs induced by histamine as well as increase the perfusion rate of isolated lung preparation of guinea pig. These actions, however, may be bloeked by propranolol. Besides, these coumarins cannot increase the heart rate and arterial blood pressure in anesthetized rats. All this shows that the antiasthmatic effect of total coumarins in the fruit of Cnidium monnieri is mediated by β2-receptor.