(A) Fractionation procedure of Rubus coreanum and (B) comparative effects of four fractions (water [H
O], butanol [BuOH], ethylacetate [EtOAc], and methylene chloride [CH
]) extracted from Rubus coreanum on the inhibition of phenylephrine (PE)-induced contractile responses in the isolated thoracic aortic strips of rats. The contractile responses were induced by adding 10 μM PE at a 120-min interval after adaptation with normal Krebs solution for 2 h prior to initiation of the experimental protocol. Each column denotes active tension induced evoked by 10 μM PE before and after adding fractions (400 μg/mL) of EtOAc, CH2Cl2, BuOH, and H2O, respectively. Vertical bars represent the standard error of the mean. Ordinate: the active tension (% of control, 1.6 ± 0.1 g [10 μM]). Abscissa: after treatment of each fraction. Statistical difference was obtained by comparing its control with each fraction-pretreated group. *p < 0.05. **p < 0.01.