Abstract
Pericarpium Citri Nobilis Viride, a traditional herb medicine, has been used in Korea and China for many centuries as a treatment for respiratory disease. The purpose of the present study was to determine the effect of Pericarpium Citri Nobilis Viride on histamine-induced tracheal smooth muscle contraction in rats. Guinea pigs(500g , female) were killed by $CO_2$ exposure and a segment (8-10mm) of the thoracic trachea from each 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 which evoked 50% of maximal response $(ED_{50})$ was obtained from cumulative dose response curves for histamine $(10^{-7}-10^{-4}M)$. Contractions evoked by histamine ($ED_{50}$) were inhibited significantly by Pericarpium Citri Nobilis Viride. The mean percent inhibition was 53.7% (P<0.05) after 1.5mg／ml Pericarpium Citri Nobilis Viride, and 87.7% (P<0.01) after 5.0mg／ml Pericarpium Citri Nobilis Viride. Propranolol $(10^{-7}M)$ slightly but significantly attenuated the inhibitory effects of Pericarpium Citri Nobilis Viride. Following treatment with propranolol the mean present inhibition caused by 1.5 and 5.0mg／ml Pericarpium Citri Nobilis Viride. Indomethacin and methylene blue $(10^{-7}M)$ did not significantly alter the inhibitory effect of Pericarpium Citri Nobilis Viride These results indicate that Pericarpium Citri Nobilis Viride can relax histamine-induced contraction of guinea pig tracheal smooth muscle, and that this inhibition involves in part symphathetic nerve system.
