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Effects of hypoxia and post-hypoxic recovery on chick retinal pigment epithelium potentials and light-evoked responses in vitro.

Abstract：

PURPOSE:To determine the cellular mechanisms involved in the hypoxia-induced alteration of the retinal pigment epithelium (RPE) potentials and the light-evoked responses of the RPE in chicks. In addition, to determine the mechanisms involved in the recovery of the RPE during the post-hypoxic period. METHODS:In vitro preparations of chick retina-RPE-choroid were studied by potassium-selective microelectrodes placed in the subretinal space. In addition, single-barrel microelectrodes were used to obtain intracellular recordings from the RPE cells. The perfusate was bubbled continuously with 95% oxygen and 5% carbon dioxide for the control condition and replaced by 95% nitrogen and 5% carbon dioxide to induce hypoxia. RESULTS:Hypoxia induced a significant reduction of the trans-tissue potential which was found to result from the depolarization of the apical membrane of the RPE. This depolarization was induced by an increase of subretinal [K+]o. The c-wave was also markedly decreased or abolished during hypoxia. There were two phases of post-hypoxic recovery: an initial small increase in the trans-tissue potential resulting from a basal membrane depolarization followed by an apical membrane hyperpolarization. The trans-tissue potential and the c-wave also were supernormal in two phases during this post-hypoxic period. The c-wave amplitude was temporarily elevated (263.7 +/- 77.4% of pre-hypoxic control) because of the enhanced trans-epithelial c-wave and without a light-evoked decrease in subretinal [K+]o. CONCLUSIONS:The trans-tissue potential and the c-wave were markedly decreased during hypoxia. During the post-hypoxic period, both potential recovered with transient supernormalities in two phases. The results suggested that the hypoxic changes resulted directly from changes of the RPE membranes and indirectly from a change in the subretinal [K+]o but were not mediated by the light-evoked decrease in subretinal [K+]o.

journal_name

Curr Eye Res

journal_title

Current eye research

authors

Nakazaki S,Nao-i N,Sawada A

doi

10.1080/02713689808951219

subject

Has Abstract

pub_date

1998-04-01 00:00:00

pages

384-91

issue

eissn

0271-3683

issn

1460-2202

journal_volume

pub_type

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Effects of hypoxia and post-hypoxic recovery on chick retinal pigment epithelium potentials and light-evoked responses in vitro.