Abstract: Aim ＆ methods The antagonism of L-dicentrine to contraction of isolated porcine coronary artery strips induced by 5-HT KCl and Ca²⁺was observed with U-135 electrophsiological recorder.Results The contract ions induced by 5-HT KCl and Ca²⁺after high K⁺depolarization in the strips of porcine coronary artery were markediy inhibited by L-dicentrine. L-dicentrine significantly depressed maximal response and caused rightward displacement of the dose-response curve.Showing a non-competitive antagonism.In Ca²⁺free solution, L-dicentrine inhibited 5-HT-induced contraction of porcine coronary artery ,which is dependent on Ca²⁺relesed from intracellular store.After Ca²⁺concentration in bath solution was restored, L-dicentrine did not influence the contraction of porcine coronary artery depending on extracellular Ca²⁺.Conclusion L-D have significant relaxation on porcine coronary artery ,which possibly has 5-HT receptor and histamine receptor.

Key words: L-dicentrine porcine, coronary artery, relaxation