title: In vivo response of the rat's retinal pigment epithelium to azide: changes induced by light damage.
abstract: Functional changes in retinal pigment epithelium (RPE) associated with light-induced retinal damage were studied by measuring transocular potential changes evoked by injections of azide and thiocyanate (SCN-). The retinal damage by light in the rat is classified into two types: Type 1, rod cell death associated with RPE deterioration; Type 2, the loss of rod cells without RPE deterioration. To study the type 1 damage, littermate pairs of long-term dark-adapted adult albino rats were tested at 1 h and 10 d after the exposure to green light of 1,200 lx for 1/2 to 24 h. Time course of the damage progress was also followed for 12 h. We found that 1) RPE was affected rapidly by the damaging light, 2) the exposure length determined the ultimate degree of RPE damage, 3) damaging effects on RPE proceeded slower and weaker after exposure than during continuous light, 4) progress of the damage in RPE was two-phasic; during the first phase, the SCN- response was enhanced and the azide response was reduced; both responses were decreased rapidly in the second phase. The first phase was assumed to indicate a depolarization of the basolateral membrane of RPE, and the second phase to manifest the structural deterioration of RPE. The type 2 damage was studied in young rats with exposure to weak light for 28 d. At 30 d after the exposure, a-wave of the ERG and number of rod cells were substantially reduced but azide and SCN- responses were affected slightly.
authors.affiliation: Department of Ophthalmology, University of Kansas Medical Center, Kansas City 66103.
authors.forename: H
authors.initials: H
authors.lastname: Ando
authors.forename: W K
authors.initials: WK
authors.lastname: Noell
mesh_terms: D000818:Animals; D001386:Azides / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects; D004247:DNA / Q000032:analysis; D004594:Electrophysiology; D004596:Electroretinography; D008027:Light / Q000009:adverse effects*; D008297:Male; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D051381:Rats; D017948:Retinal Rod Photoreceptor Cells / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D019810:Sodium Azide; D013861:Thiocyanates / Q000633:toxicity*
chemical_list: D001386:Azides; D013861:Thiocyanates; C024553:sodium thiocyanate; D004247:DNA; D019810:Sodium Azide