March 2, 2009 -- The stench of rotten eggs seems an unlikely aphrodisiac. But new research suggests that a foul-smelling gas could someday become the target of new drugs for erectile dysfunction.
Hydrogen sulfide is present in raw natural gas and in the odor of rotting eggs. Our bodies also produce tiny quantities of hydrogen sulfide, but the gas was long thought to be only a toxic by-product of metabolism.
Research early this decade revealed that many animals actually use hydrogen sulfide to help expand blood vessels. Chemicals that create these expansions in blood flow are called vasodilators.
In previous experiments in mice and monkeys, injecting hydrogen sulfide opened blood vessels and improved erections. But the same chemical pathways weren't yet proven to function in people.
Hydrogen Sulfide for Erectile Dysfunction
For the new study, researchers at the University of Naples in Italy studied penile tissue samples obtained from humans.
They found the same enzymes that produce hydrogen sulfide in animals were present and functional in human tissue. The chemical reactions that produce hydrogen sulfide were generally the same, too. The scientists concluded that hydrogen sulfide does likely contribute to erections in men, just as in animal studies.
Viagra and other drugs for erectile dysfunction work by boosting the effects of nitric oxide, another vasodilator. Viagra slows down a specific enzyme, prolonging nitric oxide's actions. Blood vessels in the penis expand, and erections result from the increased blood flow.
The researchers say greater understanding of hydrogen sulfide's separate chemical pathway could eventually lead to new treatments for erectile dysfunction. The study appears in the online early edition of the journal Proceedings of the National Academy of Sciences.