Effect ot Radix Asteris on Airway Smooth Muscle

Radix Asteris has been used in Korea for many centuries as a treatment for respiratory disease. The effect of Radix Asteris on tracheal smooth muscle is not known. The purpose of the present study is to determine the effect of Radix Asteris on histamine induced tracheal smooth muscle contraction in rats and guinea pigs. Guinea pig(500g, male) and Sprague Dawley rats (250g, male) were killed by exposure and a segment (8-10mm) of the thoracic trachea from each rat and guinea pig was cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 0.5g loading tension. The dose of histamine (His) which evoked 50% of maximal response () was obtained from cumulative dose response curves for histamine . Contractions evoked by His () were inhibited significantly by Radix Asteris. In guinea pig tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was 120.5% (p Radix Asteris. In rat tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was 135.4% (p Radix Asteris. Propranolol slightly but significantly attenuated the inhibitory effects of Radix Asteris. Following treatment with propranolol, the mean percent inhibition caused by Radix Asteris fell to 44.6% in guinea pig induced by histamine contraction and by Radix Asteris fell to 18.7% (p did not significantly alter the inhibitory effect of Radix Asteris. These results indicate that Radix Asteris can relax histamine induced contraction of guinea pig and rat tracheal smooth muscle, and that this inhibition involves sympathetic effects.