title: Rabbit conjunctival epithelium transports fluid, and P2Y2(2) receptor agonists stimulate Cl(-) and fluid secretion.
abstract: Rabbit conjunctival epithelium exhibits UTP-dependent Cl(-) secretion into the tears. We investigated whether fluid secretion also takes place. Short-circuit current (I(sc)) was 14.9 +/- 1.4 microA/cm(2) (n = 16). Four P2Y(2) purinergic receptor agonists [UTP and the novel compounds INS365, INS306, and INS440 (Inspire Pharmaceuticals)] added apically (10 microM) resulted in temporary (approximately 30 min) I(sc) increases (88%, 66%, 57%, and 28%, respectively; n = 4 each). Importantly, the conjunctiva transported fluid from serosa to mucosa at a rate of 6.5 +/- 0.7 microl x h(-1) x cm(-2) (range 2.1--15.3, n = 20). Fluid transport was stimulated by mucosal additions of 10 microM: 1) UTP, from 7.4 +/- 2.3 to 10.7 +/- 3.3 microl x h(-1) x cm(-2), n = 5; and 2) INS365, from 6.3 +/- 1.0 to 9.8 +/- 2.5 microl. h(-1) x cm(-2), n = 5. Fluid transport was abolished by 1 mM ouabain (n = 5) and was drastically inhibited by 300 microM quinidine (from 6.4 +/- 1.2 to 3.6 +/- 1.0 microl x h(-1) x cm(-2), n = 4). We conclude that this epithelium secretes fluid actively and that P2Y(2) agonists stimulate both Cl(-) and fluid secretions.
authors.affiliation: Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: K
authors.initials: K
authors.lastname: Kuang
authors.forename: B
authors.initials: B
authors.lastname: Yerxa
authors.forename: Q
authors.initials: Q
authors.lastname: Wen
authors.forename: H
authors.initials: H
authors.lastname: Rosskothen
authors.forename: J
authors.initials: J
authors.lastname: Fischbarg
mesh_terms: D000818:Animals; D001692:Biological Transport; D001826:Body Fluids / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003228:Conjunctiva / Q000187:drug effects / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D011817:Rabbits; D058473:Receptors, Purinergic P2Y2
chemical_list: D002712:Chlorides; D058910:Purinergic P2 Receptor Agonists; D058473:Receptors, Purinergic P2Y2