title: Human retinal pigment epithelial cells possess V1 vasopressin receptors.
abstract: Membrane preparations of cultured human retinal pigment epithelial (RPE) cells were incubated with various concentrations of [3H]arginine vasopressin (AVP) in the presence and absence of 10 microM nonradioactive AVP. Saturable, specific binding to a single site with a Kd of 6.2 nM and Bmax of 111 fmol/mg protein was detected. Vasopressin had no effect on RPE cyclic AMP levels measured by radioimmunoassay. Intracellular calcium fluxes were measured by spectrofluorometry of RPE cell suspensions preloaded with quin 2. The baseline cytosolic calcium level was 217 +/- 20 nM, and AVP caused a concentration-dependent increase in this level with a 3.5-fold maximal response at 10(-6) M and an EC50 of 120 nM. The production of inositol phosphates was measured in RPE preloaded with [3H]myoinositol, and AVP caused a concentration-dependent increase in their production with a 2.1-fold maximal response at 10(-5) M and an EC50 of 80 nM. A specific vasopressin receptor antagonist, SKF 101926, prevented the AVP-induced increase in calcium mobilization and inositol phosphate production in RPE. These data suggest that RPE cells possess V1 AVP receptors coupled to calcium mobilization and inositol phosphate metabolism.
authors.affiliation: University of Virginia Health Sciences Center, Department of Ophthalmology, Charlottesville.
authors.forename: Z
authors.initials: Z
authors.lastname: Friedman
authors.forename: T M
authors.initials: TM
authors.lastname: Delahunty
authors.forename: J
authors.initials: J
authors.lastname: Linden
authors.forename: P A
authors.initials: PA
authors.lastname: Campochiaro
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin; D013050:Spectrometry, Fluorescence; D014667:Vasopressins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000634:Aminoquinolines; D057911:Angiotensin Receptor Antagonists; D005456:Fluorescent Dyes; D007295:Inositol Phosphates; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D014667:Vasopressins; D001127:Arginine Vasopressin; C050890:1-((beta-mercapto-beta)beta cyclopentamethylenepropionic acid)-2-(O-ethyl-Tyr)-4-Val-9-des-Gly-arginine vasopressin; D000242:Cyclic AMP; C035739:Quin2; D002118:Calcium