The chemical Rho-associated protein kinase (ROCK) helps keep blood vessels in your penis contracted, so that they don’t fill up with blood — until you get an erection. Blocking this enzyme, such as with the experimental drug Y-27632, should presumably help erections.
It appears to do this using non-nitric oxide pathways. This is significant because it suggests an approach for treating ED in patients who do not respond to Viagra. However, its effect on other blood vessels in your body (your heart, your eyes, your brain, etc) is not known at this point. However, if it can be used safely, it may someday be used in combination therapy with Viagra. To use a car analogy, it will be like hitting the gas (Viagra, which increases blood vessel relaxation) AND taking your foot off the breaks (because ROCK inhibitors will reduce contraction of blood vessels).
For information on Y-27632, go to THIS LINK.
Here is another article about inhibition of ROCK: THIS LINK.