title: Topical phenylephrine for mydriasis affects rabbit retinal pigment epithelial transport.
abstract: Rabbit retinal pigment epithelium (RPE) has an alpha-1 adrenoreceptor that substantially reduces RPE short circuit current (Isc) when stimulated. Since phenylephrine is a potent alpha adrenergic agonist frequently used to obtain pupil dilation, we examined the effect of topically applied phenylephrine for pupil dilation on RPE transport. Naive black dutch-belted rabbits received either one drop of 10% phenylephrine applied at t = 0 and t = 30 min or one drop of 1% cyclopentolate applied at t = 30 min. At t = 50 min, RPE-choroid-sclera explants from these animals were sealed in an Ussing chamber. At t = 60-70 min, 1.4 X 10(-4) M epinephrine was introduced into both sides of the Ussing chamber. The change in Isc produced by epinephrine was measured. The Isc reduction in rabbits receiving phenylephrine was 26% (+/- 5% SD, n = 6). The Isc reduction in rabbits receiving cyclopentolate was 39% (+/- 6% SD, n = 5). These values are significantly different (P less than 0.02, student two-tail t-test). These results indicate that topical phenylephrine reached the RPE in vivo and prestimulated the alpha-1 adrenoreceptors.
authors.affiliation: Eye Research Institute of Retina Foundation, Boston, Massachusetts.
authors.forename: D A
authors.initials: DA
authors.lastname: Frambach
authors.forename: J L
authors.initials: JL
authors.lastname: Valentine
authors.forename: J J
authors.initials: JJ
authors.lastname: Weiter
mesh_terms: D000287:Administration, Topical; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D009184:Mydriatics / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology*; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits
chemical_list: D009184:Mydriatics; D010656:Phenylephrine; D004837:Epinephrine