Fig. 7.

Influence of endothelin-1 (ET-1) on blood vessels in the optic nerve head and adjacent retina (reproduced from [31]). (A) Circulating ET-1 reaches just the endothelial cells (A1) and has a more or less neutral effect on the size of the vessels. If the blood-brain barrier is disrupted (A2), it reaches the vascular smooth muscle cells directly and induces vasoconstriction. (B) Hypoxic retina produces ET-1, which diffuses also to neighboring vessels. (C) ET-1 diffuses from fenestrated capillaries of the choroid into the optic nerve head and adjacent retina. This can induce a local constriction of the veins and in turn increase retinal venous pressure