REVIEW Vardenafil inhibits the cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by vardenafil enhances erectile function by increasing the amount of cGMP.
Dimitriadis F, Tsampalas S, Tsounapi P, Giannakis D, Chaliasos N, Baltogiannis D, Miyagawa I, Saito M, Takenaka A, Sofikitis N (2012). Effects of phosphodiesterase-5 inhibitor vardenafil on testicular androgen-binding protein secretion, the maintenance of foci of advanced spermatogenesis and the sperm fertilising capacity in azoospermic men. Andrologia. 44 Suppl 1:144-53. PMID 21793866.
Reneerkens OA, Rutten K, Akkerman S, Blokland A, Shaffer CL, Menniti FS, Steinbusch HW, Prickaerts J (2012). Phosphodiesterase type 5 (PDE5) inhibition improves object recognition memory: indications for central and peripheral mechanisms. Neurobiol Learn Mem. 97(4):370-9. PMID 22426465.