Erection is an event associated with vasodilation. Much of the focus has been on the nitric oxide pathway, in part because of the discovery that Viagra supports erections by blocking phosphodiesterase type 5 (PDE5), the enzyme that reverses the effects of nitric oxide in vasodilation.

But there is another pathway – the prostacyclin pathway. In this pathway, arachidonic acid is broken down into prostaglandin I2 (prostacyclin), which then has vasodilatory and antiproliferation properties.
This is another avenue of research, especially for amateurs like me, because of the many herbs that work on this pathway. More on this approach in the near future, when I have time.
Some information on this pathway:
http://www.nutriguard.com/NADPHox-ED.pdfA useful inhibitor that might help with this pathway is APOCYNIN, similar to vanilla.

Described here: http://en.wikipedia.org/wiki/Apocynin