Figure 2: (a and b) Inhibitory effects of vardenafil (10−7-10−6 M) on the contraction induced by phenylephrine (10−9-10−4 M) or KCl (10-60 mM) in endothelium-denuded rat pulmonary artery rings. Results are presented as mean ± standard error of the mean of 12 rats. *P < 0.05 and **P < 0.01 versus control group
