When the arteries that feed the spongy tissue of the penis receive signals from the brain, they begin to dilate. This signal, carried by nitric oxide in the blood, turns on an enzyme causing a molecule known as cGMP (cyclic Guanosine Monophosphate). This causes smooth muscle in the artery wall to relax allowing the blood vessels to dilate. Though cGMP is normally broken down by another enzyme known as PDE (Phosphodiesterase), Kamagra™ inhibits this reaction allowing the blood vessels to remain dilated as long as there is some natural stimulation present. The inhibiting of the PDE reaction will not last for ever and will start once all stimulation is no longer present.