Electrical responses of the rat's retinal pigment epithelium to azide and thiocyanate.
In the rat under urethane anesthesia, a fast intravenous injection of a bolus of sodium azide elicited a transient cornea-positive change in transocular potential (azide response). A bolus injection of sodium thiocyanate (NaSCN) produced a cornea-negative response (SCN- response) with a similar rising phase as the azide response, but with a faster return from the peak. The peak amplitude depended on bolus volume, concentration, animal strain, and age. For more than 24 h, the azide and SCN- responses could be recorded repeatedly from a single rat with little variation in peak amplitudes. Following an administration of iodate, known to degenerate the retinal pigment epithelium (RPE), the transocular d.c. potential decreased; the azide response became smaller and then was inverted in polarity, whereas the SCN- response became larger. Azide and SCN- are assumed to depolarize and hyperpolarize the basal membrane of RPE, respectively. The equilibrium potential of ions passing through the putative azide-sensitive channels is assumed less negative than resting potential of RPE cells. The SCN- response probably represents a diffusion potential of SCN- permeating through anionic channels at a higher rate than Cl-. Results demonstrate the feasibility of in vivo electrophysiological measurement of the functional state and the structural integrity of RPE under pathological conditions.
Ando
H
H
Department of Ophthalmology, University of Kansas Medical Center, Kansas City 66103.
Noell
W K
WK
D000818:Animals; D001386:Azides / Q000633:toxicity*; D004594:Electrophysiology; D005260:Female; D007452:Iodates / Q000494:pharmacology; D008297:Male; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019810:Sodium Azide; D013861:Thiocyanates / Q000633:toxicity*
D001386:Azides; D007452:Iodates; D013861:Thiocyanates; C024553:sodium thiocyanate; D019810:Sodium Azide