비아그라에 대한 편견 없는 견해
PDE3 is associated answerable for cardiac contractility. Sildenafil is simply about ten-fold as potent for PDE5 as compared to PDE6, an enzyme present in the retina which happens to be associated with the phototransduction pathway with the retina. This reduce selectivity is regarded as The premise for abnormalities associated with colour vision [se