비아그라에 대해 거의 알려지지 않은 사실

Sexual stimulation that causes an erection will cause the production and launch of nitric oxide while in the penis. Nitric oxide brings about an enzyme, guanylate cyclase, to supply cyclic guanosine monophosphate (cGMP) which is mainly accountable for increasing and reducing the size of blood vessels carrying blood to and within the penis and causi