Mechanism Involved in the Spasmolytic Effect of a Mixture of Two Triterpenes, Cycloartenol and Cycloeucalenol, Isolated from Herissanthia tiubae in the Guinea-Pig Ileum - Gomes, Ana Yara S; Souza, Maria de Fátima V; Cortes, Steyner F; Lemos, Virgínia S (Planta Medica, 2005)