Effect of diinosine polyphosphates on intraocular pressure in normotensive rabbits

Abstract

The ability of diinosine polyphosphates, diinosine triphosphate (Ip 3I), diinosine tetraphosphate (Ip 4I) and diinosine pentaphosphate (Ip 5I) to modify intraocular pressure in normotensive New Zealand white rabbits was tested. Ip 5I produced increase in intraocular pressure, while Ip 3I and Ip 4I produced a decrease. Ip 4I was the most effective reducing intraocular pressure inducing a maximal decrease of intraocular pressure to 74.2 ± 2.5% compared with the control value. Dose-response analysis demonstrated a concentration dependent pattern which presented a pD 2 value of 6.19 ± 0.18, equivalent to an EC 50 of 0.63 μM. Regarding the underlying mechanism used by Ip 4I to reduce intraocular pressure, studies with agonists and antagonists revealed that Ip 4I reduces intraocular pressure via P2Y receptors in the eye. We suggest that topical application of Ip 4I to the cornea has therapeutic potential for lowering intraocular pressure, a major risk factor for glaucoma.