title: Pharmacological characterization of P2Y receptor subtypes on isolated tiger salamander Müller cells.
abstract: Müller cells express a variety of neurotransmitter receptors that permit them to "sense" the extracellular environment within the retina. We have used a battery of agonists and antagonists to characterize the purinergic receptor subtypes expressed on isolated tiger salamander Müller cells. Changes in intracellular calcium ion concentration ([Ca(2+)](i)) in Müller cells were measured using the Ca(2+) indicator dye Fura-2 and digital imaging microscopy. ATP, 2-methylthio-ATP, 2-methylthio-ADP, ADP, UTP, UDP, deoxyATP, and 3'-O-(4-benzoyl)benzoyl ATP evoked increases in [Ca(2+)](i) in both the presence and absence of extracellular Ca(2+). Therefore, the increases we observed were likely due to intracellular Ca(2+) release mediated by G-protein-coupled P2Y receptor activation, rather than Ca(2+) influx via P2X receptor channels. The P2Y(1) receptor agonists 2-methylthio-ATP, 2-methylthio-ADP, and ADP evoked increases in [Ca(2+)](i) that were inhibited by the P2Y(1) receptor antagonists adenosine 3'-phosphate 5'-phosphosulfate and 2'-deoxy-N(6)-methyleneadenosine-3',5'-bisphosphate. Responses to ADP were not completely inhibited by the P2Y(1) receptor antagonists. The residual response to ADP could be mediated by P2Y(13) receptors. UTP evoked an increase in [Ca(2+)](i) that was partially inhibited by suramin, suggesting that Müller cells express P2Y(2) and P2Y(4) receptors. The P2Y(6) receptor agonist UDP, and the P2Y(11) receptor agonists deoxyATP, and 3'-O-(4-benzoyl)benzoyl ATP, evoked increases in [Ca(2+)](i) in Müller cells. We conclude that isolated tiger salamander Müller cells express P2Y(1), P2Y(2), P2Y(6), P2Y(11), and possibly P2Y(4) and P2Y(13) receptors. Therefore, the physiological release of ATP, ADP, UTP, and UDP and/or their accumulation in the retina under pathological conditions could stimulate increases in [Ca(2+)](i) in Müller cells.
authors.affiliation: Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Reifel Saltzberg
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Garvey
authors.forename: Susan A
authors.initials: SA
authors.lastname: Keirstead
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000557:Ambystoma / Q000033:anatomy & histology / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D016257:Fura-2; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014530:Uridine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000378:metabolism / Q000494:pharmacology
chemical_list: C546382:P2RY1 protein, human; C109734:P2RY11 protein, human; C546385:P2RY2 protein, human; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; C099845:purinoceptor P2Y6; D014530:Uridine Diphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2; D014544:Uridine Triphosphate