Vascular Activity of (-)-Anonaine, (-)-Roemerine and (-)-Pukateine, Three Natural 6a(R)-1,2-Methylenedioxyaporphines with Different Affinities for α1-Adrenoceptor Subtypes - Valiente, M; D’Ocon, P; Noguera, M A; Cassels, B K; Lugnier, C; Ivorra, M D (Planta Medica, 2004)