Hydrogen sulfide as a mediator of human corpus cavernosum smooth-muscle relaxation

R.D.D. Bianca, R. Sorrentino, Pasquale Maffia, V. Mirone, C. Imbimbo, F. Fusco, R. De Palma, L.J. Ignarro

Research output: Contribution to journalArticlepeer-review

146 Citations (Scopus)


Hydrogen sulfide (H2S) is synthesized by 2 enzymes, cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). L-Cysteine (L-Cys) acts as a natural substrate for the synthesis of H2S. Human penile tissue possesses both CBS and CSE, and tissue homogenates efficiently convert L-Cys to H2S. CBS and CSE are localized in the muscular trabeculae and the smooth-muscle component of the penile artery, whereas CSE but not CBS is also expressed in peripheral nerves. Exogenous H2S [sodium hydrogen sulfide (NaHS)] or L-Cys causes a concentration-dependent relaxation of strips of human corpus cavernosum. L-Cys relaxation is inhibited by the CBS inhibitor, aminoxyacetic acid (AOAA). Electrical field stimulation of human penile tissue, under resting conditions, causes an increase in tension that is significantly potentiated by either propargylglycine (PAG; CSE inhibitor) or AOAA. In rats, NaHS and L-Cys promote penile erection, and the response to L-Cys is blocked by PAG. Our data demonstrate that the L-Cys/H2S pathway mediates human corpus cavernosum smooth-muscle relaxation.
Original languageEnglish
Pages (from-to)4513-4518
Number of pages5
JournalProceedings of the National Academy of Sciences
Issue number11
Publication statusPublished - 17 Mar 2009


  • cystathionine beta-synthase (CBS)
  • cystathionine gamma-lyase (CSE)
  • H2S
  • penile erection
  • L-cysteine

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