The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 12 No. 2 • April 2009

Hydrogen Sulfide as a Mediator of Erection via Corpus Cavernosum Smooth-Muscle Relaxation

We have written before on some of the interesting new findings concerning hydrogen sulfide, another endogenously produced gas (other gases important in physiological signaling include nitric oxide and carbon monoxide). In the case of hydrogen sulfide, it has been found to mediate vascular relaxation. Early work with animals has indicated that hydrogen sulfide facilitates erectile function.1

A new study1 reports further to extend the data to humans. Using human corpus cavernosum (obtained during a surgical procedure), the researchers demonstrate that human penile tissues contain both enzymes required for conversion of L-cysteine to hydrogen sulfide, cystathione beta-synthase (CBS) and cystathione gamma-lyase (CSE). Providing human corpus cavernosum strips with sodium hydrogen sulfide (an exogenous source of hydrogen sulfide) or L-cysteine (converted by CBS and CSE to hydrogen sulfide) caused the strips to relax in a concentration-related manner.

The authors found that an “intracavernous administration of L-cysteine (30 ug per rat) caused a significant increase in intracavernous pressure. Intravenous administration of [the CSE inhibitor] PAG (50 mg/kg. at 30 and 60 minutes significantly reduced L-cysteine-elicited rat penile erections.” The investigators did not examine how much L-cysteine would need to be taken orally to get a similar effect.

As the authors note, “[t]o what extent this pathway complements the L-Arg/NO signaling pathway in promoting erectile function is presently unknown.”

If you take a cysteine supplement, be sure to take 2–3 times as much vitamin C as cysteine to help prevent the formation of cystine stones. Eggs are a good food source of cysteine; each egg contains about 250 mg. We supplement our diet with the cysteine in Root Food™.


  1. d’Emmanuele di Villa Bianca et al. Hydrogen sulfide as a mediator of human corpus cavernosum smooth-muscle relaxation. Proc Natl Acad Sci USA 106(11):4513-8 (2009).

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