Journal of Neuroscience, Vol 9, 1968-1976, Copyright © 1989 by Society for Neuroscience
Effects of DIDS on the chick retinal pigment epithelium. I. Membrane potentials, apparent resistances, and mechanisms
RP Gallemore and RH Steinberg
Department of Physiology, University of California, San Francisco 94143.
While little is known about the transport properties of the retinal pigment
epithelium (RPE) basal membrane, mechanisms for anion movement across the
basal membrane appear to be present (Miller and Steinberg, 1977; Hughes et
al., 1984; Miller and Farber, 1984). This work examines the
electrophysiological effects of the anion conductance blocker, 4,4'-
diisothiocyanostilbene-2,2'-disulfonate (DIDS) on the basal membrane of an
in vitro preparation of chick retina-RPE-choroid. DIDS (10-125 microM),
added to the choroidal bath, decreased the transtissue potential by
decreasing the potential across the RPE. Intracellular RPE recordings
showed that DIDS affected the membrane potential in 2 phases, initially
hyperpolarizing the basal membrane and then, after prolonged exposure,
depolarizing the apical membrane. Resistance assessment by transtissue
current pulses and intracellular c-wave recordings suggested that DIDS
increased basal membrane resistance (Rba) during the first phase and
increased apical membrane resistance (Rap) during the second phase.
Measurements of intracellular Cl- activity (aiCl) showed that Cl- was
actively accumulated by the chick RPE since it was distributed above
equilibrium across both the apical and basal membranes. Perfusion of the
basal membrane with 50 microM DIDS significantly increased aiCl-. The
DIDS-induced basal membrane hyperpolarization, apparent increase in Rba,
and increase in aiCl- are all consistent with Cl- -conductance blockade.
During the second phase, apical membrane responsiveness to the light-evoked
decrease in subretinal [K+]o (Oakley, 1977) was reduced an average of 58%.
This finding, given the second-phase apical membrane depolarization and
apparent increase in Rap, is consistent with a decrease in apical membrane
K+ conductance.(ABSTRACT TRUNCATED AT 250 WORDS)
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