Ocular renin-angiotensin: immunohistochemical evidence for the presence of prorenin in eye tissue.

Angiotensin II (A2) is a vasoconstrictor generated by the renin-angiotensin system. A2 appears to act also as an angiogenic factor. Recent evidence suggests that renin is synthesized at many tissue sites and may generate A2 locally. Local A2 may have important functions in the normal and diseased eye. We examined eight human eyes by immunostaining with an antibody to prorenin, the biosynthetic precursor of renin. In all eyes, prorenin staining was extensive in the pars plicata of the ciliary body suggesting that the ciliary body synthesizes renin and this renin may be part of an ocular A2 generating system.