Figure 3.

NOS expression inside the eye. (A) Three types of NOSs are constitutively expressed or induced in various ocular tissues and cells. NO is involved in all vital ocular phenomena. eNOS and nNOS are expressed constitutionally in both the anterior and posterior parts of the eye, and iNOS can be actively induced in inflammatory conditions. (B) Different types of cells in the whole retinal layer express eNOS and nNOS. iNOS can be induced in the retina in inflammatory conditions, and infiltrating macrophages also express iNOS. NO, nitric oxide; eNOS, endothelial nitric oxide synthase; nNOS, neuronal nitric oxide synthase; iNOS, inducible nitric oxide synthase.