Abstract: Objective: To study the effect of phycocyanin on myocardial contraction action of isolated toad heart and the mechanism involved in this action. Methods: Isolated toad heart model produced by Straub’method was used to observe the change of myocardial contraction force and cardiac rate after phycocyanin were used. Results: At three concentration (1.2, 4.5, 8.4μg /ml)the myocardial contraction force increased extremely strikingly (p<0.01),But didn’t show the effect on toad cardiac rate. Propranolol and verapamil antagonized the effectof phycocyanin (8.4μg /ml). Conclusions: The main effects of phycocyanin were that it haspositive inotropic action, the mechanism of the action might be related to the excitation of β-receptor and calcium channel.

Key words: phycocyanin, heart, positive inotropic action, β-receptor, calcium channel