Nitrogenoxyd aktiverer derefter enzymet guanylatcyklase, hvilket resulterer i øgede koncentrationer af cyklisk guanosinmonofosfat (cGMP), som fører til afslapning af den glatte muskulatur i corpus cavernosum og tillader blodet at strømme til.
Nitric oxide then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood.