Additive effects of Artemisia capillaris extract and scopoletin on the relaxation of penile corpus cavernosum smooth muscle

The objective was to investigate the cellular effect and action mechanism of Artemisia capillaris extract (ACE) and its component, scopoletin, on penile corpus cavernosum smooth muscle (PCCSM). In vitro study with PCCSM, the precontracted PCCSM with phenylephrine was treated with ACE or scopoletin. Cyclic nucleotides in the perfusate were measured by radioimmunoassay and expression of protein and mRNA of endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase in the perfused PCCSM were measured by western blot and real-time PCR, respectively. The interaction of ACE or scopoletin with udenafil was also evaluated. ACE and scopoletin exerted a significant and concentration-dependent relaxation in PCCSM. The perfusion with ACE or scopoletin significantly increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) and the perfusion with ACE or scopoletin increased the expression of eNOS mRNA and protein. Furthermore, ACE or scopoletin enhanced udenafil-inducing relaxation in PCCSM. ACE and scopoletin relaxed the PCCSM mainly by activating nitric oxide–cGMP system and cAMP pathway and they may be additive therapeutic candidates for ED patients who do not completely respond to udenafil.