Researchers have identified an alternative pathway that regulates penile erection, offering fresh hope to the 40% of impotent men for whom Viagra is ineffective. Viagra increases the dilatory effects of nitric acid in the penis blood vessels, increasing blood flow and causing erection.

A team lead by Clinton Webb (Medical College of Georgia, Augusta, USA) took a different approach by looking for molecules that can block smooth muscle cell contraction.

They hypothesized that Rho-kinase, which works as a vasoconstrictor by activating myosin light chain, was a promising pharmacological target. A drug called Y-27632 blocked Rho-kinase activity and rapidly induced erections in laboratory rats in a nitric oxide-independent manner.

This study, published in the January issue of Nature Medicine, offers a new pathway for treating erectile dysfunction. JW

Jonathan Weitzman
Trends in Molecular Medicine