Figure 3: Concentration-dependent relaxing action of tanshinone IIA in the isolated SHR aortic rings contracted with phenylephrine (10 nmol l−1) or KCl (40 mmol l−1). The preparation of isolated aortic rings from male SHR was described in Section 2. Data (mean ± SD) indicate the percentage dilations of the maximal contractions in eight experiments. * and ** versus vehicle-treated group in each group.