Researchers study two new drugs to find alternative treatment for men with erectile dysfunction

Close to 70 percent of men with erectile dysfunction (ED) respond to the ED drug sildenafil. However, only about 50 percent of men with diabetes- a population commonly affected by ED- achieve positive results with sildenafil. Researchers from the Smooth Muscle Research Centre at the Dundalk Institute of Technology, in Dundalk, Ireland, are studying two new drugs that may give men with diabetes-;and others for whom conventional treatment is ineffective- new hope for treating ED. The article is published ahead of print in the American Journal of Physiology- Cell Physiology.

For a successful erection to occur, the smooth muscle in the erectile tissue (corpus cavernosum) must relax, explained Keith Thornbury, PhD, corresponding author of the study. However, constant erection is prevented because the tissue contracts. The contraction is controlled by negatively charged chloride moving from inside the cells to outside. In a chain reaction, the outward flow of chloride causes calcium to flow into the cells. When calcium enters the smooth muscle cells of the erectile tissue, it contracts, preventing erection.

The research team treated cells from the corpus cavernosum of male rabbits with two different chloride channel blocking drugs. They found that both drugs were able to block the flow of chloride, causing the smooth muscle cells to relax. This is a different pathway to treating ED than sildenafil, which hinders the effects of a blood flow-regulating enzyme. "This suggests that chloride channels play an important role in maintaining detumescence [state of non-erection] in the corpus cavernosum and, therefore, might present a future target for treating erectile dysfunction," the researchers wrote.