Fig. 3.

Effects of 500 μg/mL Qing Dai (A–C) and 100 μM indigo (D–F) on concentration-response curves for acetylcholine (A and D), forskolin (B and E), and sodium nitroprusside (C and F) in rat thoracic aorta ring preparations precontracted with 0.3 μM (−)-phenylephrine. Acetylcholine (A and D), forskolin (B and E), and sodium nitroprusside (C and F) were applied cumulatively to the bath solution in the presence of vehicle (1% DMSO), 500 μg/mL Qing Dai, or 100 μM indigo. The percentage of smooth muscle relaxation was calculated with respect to basal tension before the application of contracting agents (100% relaxation) and (−)-phenylephrine (0.3 μM) steady-state contractile responses (0% relaxation). Data are presented as the mean ± standard error of the mean from 6 experiments. ^∗P < 0.05 and ^∗∗P < 0.01 vs. vehicle. When no error bar is shown, the error is smaller than the symbol.