Viagra may have helped restore sexual function in many people, but it isn't for everybody. People with nerve damage, for instance, don't respond to the drug. Now researchers have come up with a compound that may help by causing erections via a more direct mechanism.
Drugs such as Viagra work by enhancing the effects of nitric oxide in the blood. This gas relaxes smooth muscles, including those that line blood vessels, allowing blood to flow into the penis. Because nitric oxide is released from nerve endings, diabetics and other patients with nerve damage may not respond to Viagra.
Reasoning that a more direct effect on blood vessels would also cause erections, physiologist Tom Mills of the Medical College of Georgia in Augusta tested compounds that enlarge blood vessels. He injected a compound called Y-27362 into a rat's penis. The rat got an erection right away. "It was one of those neat moments when something really good happens in the laboratory," Mills says. Even small doses produced erections, the team reports in the January issue of Nature Medicine. They're working on developing a topical treatment, suspecting that injections would make potential consumers a bit squeamish.
Aside from any potential therapeutic value, the research "teaches us about a whole side of erection physiology that we've taken too lightly," says urologist Arthur Burnett of Johns Hopkins University in Baltimore. Previous work, including research that led to Viagra's development, focused on responses of erectile tissue, while this study shows that dilating blood vessels more directly also does the trick.
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