비아그라에 대한 5가지 쉬운 사실 설명

Sexual stimulation that contributes to an erection causes the production and release of nitric oxide from the penis. Nitric oxide results in an enzyme, guanylate cyclase, to generate cyclic guanosine monophosphate (cGMP) that's mostly chargeable for increasing and decreasing the scale of blood vessels carrying blood to and with the penis and causin