비아그라에 대한 5가지 쉬운 사실 설명

Sexual stimulation that brings about an erection causes the production and launch of nitric oxide in the penis. Nitric oxide triggers an enzyme, guanylate cyclase, to create cyclic guanosine monophosphate (cGMP) that is definitely principally chargeable for increasing and lowering the dimensions of blood vessels carrying blood to and from your peni