Electroretinographic Assessment of Inner Retinal Signaling in the Isolated and Superfused Murine Retina

ABSTRACT

Purpose: Longer-lasting electroretinographic recordings of the isolated murine retina were initially achieved by modification of a phosphate-buffered nutrient solution originally developed for the bovine retina. During experiments with a more sensitive mouse retina, apparent model-specific limitations were addressed and improvements were analyzed for their contribution to an optimized full electroretinogram (ERG).

Material and methods: Retinas were isolated from dark-adapted mice, transferred to a recording chamber and superfused with different solutions. Scotopic and photopic ERGs were recorded with white flashes every 3 minutes. The phosphate buffer (Sickel-medium) originally used was replaced by a carbonate-based system (Ames-medium), the pH of which was adjusted to 7.7–7.8. Moreover, addition of 0.1 mM BaCl₂ was investigated to reduce b-wave contamination by the slow PIII component typically present in the murine ERG.

Results: B-wave amplitudes were increased by the pH-shift (pH 7.4 to pH 7.7) from 22.9 ± 1.9 µV to 37.5 ± 2.5 µV. Improved b-wave responses were also achieved by adding small amounts of Ba²⁺ (100 µM), which selectively suppressed slow PIII components, thereby unmasking more of the true b-wave amplitude (100.0% with vs. 22.2 ± 10.7% without Ba²⁺). Ames medium lacking amino acids and vitamins was unable to maintain retinal signaling, as evident in a reversible decrease of the b-wave to 31.8 ± 3.9% of its amplitude in complete Ames medium.

Conclusions: Our findings provide optimized conditions for ex vivo ERGs from the murine retina and suggest that careful application of Ba²⁺ supports reliable isolation of b-wave responses in mice. Under our recording conditions, murine retinas show reproducible ERGs for up to six hours.

KEYWORDS:

• B-wave
• ex vivo
• isolated vertebrate retina
• light sensitivity
• mouse
• Murine ERG

Acknowledgments

We would like to specially thank Mrs. Renate Clemens for her dedication and hard work.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

This research program is supported by the START-Program of the Faculty of Medicine, RWTH Aachen, Germany.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This research program is supported by the START-Program of the Faculty of Medicine, RWTH Aachen, Germany.