비아그라에 대해 거의 알려지지 않은 사실

Sexual stimulation that leads to an erection brings about the output and release of nitric oxide in the penis. Nitric oxide triggers an enzyme, guanylate cyclase, to make cyclic guanosine monophosphate (cGMP) that's largely responsible for growing and decreasing the dimensions of blood vessels carrying blood to and with the penis and causing an ere