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VOL. 71 (2), 283-319, 2005 PURINERGIC SIGNALLING: THERAPEUTIC POTENTIAL

ATP, acting via both P2X and P2Y receptors, moduates retinal
neurotransmission, affecting retinal blood flow and intraocular
pressure. The ATP analogue ß,?-methylene ATP is more effective in
reducing intraocular pressure (40%) than muscarinic agonists such
as pilocarpine (25%) and b-adrenoceptor blockers (30%), raising the
potential for the use of purinergic agents in glaucoma. Suramin, a
P2 receptor antagonist, has been shown to inhibit the fibrotic wound
healing reactions that sometimes follow trabeculectomies for
surgically treating eyes with glaucoma. Topical application of
diadenosine tetraphosphate (Ap4A) has been proposed for the
lowering of intraocular pressure in glaucoma.

P2Y2 receptor activation increases salt, water and mucus excretion,
and thus represents a potential treatment for dry eye conditions (35).
In the pigmented layer of the retina, P2Y2 receptor activation
promotes fluid absorption, and may be involved in retinal detachment.
INS 37217, a long lasting synthetic P2Y2 receptor agonist, stimulates
the retinal pigment epithelium by activating P2Y2 receptors at the
apical membrane and in vivo treatment enhances the rate of
subretinal fluid reabsorption in experimentally induced retinal
detachments and may be useful for treating a variety of retinal
diseases that result in fluid accumulation in the subretinal space.
Reactive responses of Müller cells occur within 24 hours of retinal
detachment. Suramin inhibits some of these responses and may
provide a therapeutic candidate to limit the detrimental effects of
immune cell activation and Müller cell gliosis during retinal
detachment.

ATP and UTP restore the rates of both net Cl- and fluid secretion
in adenovirus type 5 infected conjunctival tissues and are considered
as potential therapeutic modulators for the treatment of various
transport defects encountered in ocular tissues in diseased and/or
inflamed states.

UTP and diadenosine tetraphosphate (Ap4A) accelerate wound
healing in the rabbit cornea, by regulating the rate of epithelial cell
migration.

The UPL rat is a dominant hereditary cataract model derived
from Sprague-Dawley rats and has been used to show that Ca2+
ATPase expression increases, while ATP control decreases in lenses

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