Light-induced pH changes in the intact retinae of normal and early diabetic rats

Andrey V. Dmitriev*, Desmond Henderson, Robert A. Linsenmeier

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Double-barreled H+-selective microelectrodes were used to measure local extracellular concentration of H+ ([H+]o) in the retina of dark-adapted anesthetized Long-Evans rats. The microelectrode advanced in steps of 30 μm throughout the retina from the vitreal surface to retinal pigment epithelium and then to the choroid, recording changes in [H+]o evoked by light stimulation. Recordings were performed in diabetic rats 1-3 months after intraperitoneal injection of streptozotocin and the results were compared with data obtained in age-matched control animals. Brief light stimulation (2.5 s) evoked changes of [H+]o with amplitudes of a few nM. Throughout the retina, there was a transient initial acidification for ~200 ms followed by steady alkalinization, although amplitudes and kinetics of these components were slightly variable in different retinal layers. No significant difference was found when the light-induced [H+]o changes recorded in various retinal layers of early diabetic rats were compared with the [H+]o changes from corresponding layers of control animals. Also, when H+-selective microelectrodes were located in the retinal pigment epithelium (RPE) layer, an increase in H+ was recorded, whose time course and amplitude were similar in control and diabetic rats. However, a striking difference between light-induced [H+]o changes in controls and diabetics was observed in the choriocapillaris, in the thin layer (10-20 μm) distal to the basal membrane of the RPE. In control rats, choroidal [H+]o decreased in a few cases, but much more often practically did not change. In contrast, diabetic rats demonstrated either an increase (in half of the cases) or no change in choroidal [H+]o. The data suggest that the active participation of the choroidal blood supply in stabilization of [H+]o could be partially compromised already at early stages of diabetes in rats. Interestingly, it appeared that the acid removal by the choroidal circulation was compromised most after 1 month of diabetes and tended to improve later.

Original languageEnglish (US)
Pages (from-to)148-157
Number of pages10
JournalExperimental eye research
Volume145
DOIs
StatePublished - Apr 1 2016

Keywords

  • Choroidal blood supply
  • Diabetes
  • Ion-selective microelectrodes
  • PH
  • Rat
  • Retina
  • Retinal pigment epithelium
  • Streptozotocin

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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