The P2Y(2) receptor agonist INS37217 stimulates RPE fluid transport in vitro and retinal reattachment in rat.
OBJECTIVE
To investigate the effects of INS37217, a synthetic P2Y(2) receptor agonist, on intracellular calcium signaling, electrophysiology, and fluid transport in vitro and on experimentally induced retinal detachment in rat eyes in vivo.


METHODS
Freshly isolated monolayers of bovine and human fetal RPE were mounted in Ussing chambers for measurements of cytosolic calcium levels ([Ca(2+)](i)), membrane voltages and resistances, and transepithelial fluid transport. Retinal detachments were experimentally produced in Long-Evans rats by injecting modified phosphate-buffered saline into the subretinal space (SRS). Experimental or vehicle solutions were injected into the vitreous, and the size of blebs in the SRS was scored under masked conditions.


RESULTS
Addition of INS37217 to Ringer's solution bathing the apical membrane transiently increased [Ca(2+)](i), altered membrane voltages and resistances and generally produced responses that were similar in magnitude to those of uridine triphosphate (UTP). In fluid transport experiments performed with the capacitance probe technique, INS37217 significantly increased fluid absorption across freshly isolated bovine and fetal human RPE monolayers. All in vitro results were blocked by apical 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), which has been shown to block P2Y(2) receptors in the RPE. Intravitreal administration of INS37217, but not UTP, in the rat model of retinal detachment enhanced the removal of SRS fluid and facilitated retinal reattachment when compared with vehicle control.


CONCLUSIONS
These findings indicate that INS37217 stimulates the RPE fluid "pump" function in vitro by activating P2Y(2) receptors at the apical membrane. In vivo INS37217 enhances the rates of subretinal fluid reabsorption in experimentally induced retinal detachments in rats and may be therapeutically useful for treating a variety of retinal diseases that result in fluid accumulation in the subretinal space.
Maminishkis
Arvydas
A
School of Optometry, University of California, Berkeley, USA.
Jalickee
Stephen
S
Blaug
Sasha A
SA
Rymer
Jodi
J
Yerxa
Benjamin R
BR
Peterson
Ward M
WM
Miller
Sheldon S
SS
D000042:Absorption; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D003845:Deoxycytosine Nucleotides / Q000494:pharmacology* / Q000627:therapeutic use; D004594:Electrophysiology; D006801:Humans; D007267:Injections; D017136:Ion Transport; D008564:Membrane Potentials; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D020318:Rats, Long-Evans; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2; D012163:Retinal Detachment / Q000188:drug therapy* / Q000378:metabolism; D014529:Uridine / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D014544:Uridine Triphosphate / Q000494:pharmacology; D014822:Vitreous Body; D014867:Water / Q000378:metabolism*
D003845:Deoxycytosine Nucleotides; C546385:P2RY2 protein, human; C546387:P2ry2 protein, rat; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D014867:Water; C465279:denufosol tetrasodium; D002118:Calcium; D014544:Uridine Triphosphate; D014529:Uridine