비아그라 구입 전에 알아야 할 사항

Sexual stimulation that results in an erection triggers the generation and launch of nitric oxide inside the penis. Nitric oxide will cause an enzyme, guanylate cyclase, to create cyclic guanosine monophosphate (cGMP) that is principally responsible for escalating and lowering the dimensions of blood vessels carrying blood to and from your penis an