Transretinal ERG in Studying Mouse Rod Phototransduction: Comparison With Local ERG Across the Rod Outer Segments

Abstract

METHODS. Recordings were made from dark-adapted, isolated C57BL/6J mouse retinas superfused with HEPES or bicarbonate buffered solution containing 2-mM aspartate or 20-lM DL-2-amino-4-phosphonobutyric acid to block synaptic transmission, and 50-lM BaCl 2 to block the Müller cell component. TERG responses were recorded with macroelectrodes on both sides of the retina while responses across different retinal layers were recorded with microelectrodes.RESULTS. The time-to-peak and the dominant time constant values were slightly smaller and the half-saturating stimulus was somewhat stronger in TERG compared with LERG-OS. No differences in light adaptation data were observed between the methods. LERG responses recorded across the whole photoreceptor layer were similar to those by TERG.CONCLUSIONS. TERG photoreceptor responses correspond well with the LERG-OS responses. The main differences are the nose component and slightly faster response kinetics observed by TERG. We conclude that TERG can be used for reliable quantitative investigation of phototransduction.

Determination of basal phosphodiesterase activity in mouse rod photoreceptors with cGMP clamp

“…Our specimen holder allows simultaneous visualization, stimulation and perfusion of the retina, and it is equipped with an open passage for microelectrodes enabling local electroretinography recording 47 . Local electroretinography (LERG) were recorded across the rod outer segment layer (LERG-OS) or across the whole photoreceptors (LERG-PR).…”

“…Local electroretinography (LERG) were recorded across the rod outer segment layer (LERG-OS) or across the whole photoreceptors (LERG-PR). The LERG-OS signal is directly proportional to the changes in the rod outer segment current 47 . The recording electrode (with a tip diameter ∅ of 2–5 µm) was passed to the depth of ~25 µm (OS) or ~100 µm (PR) in the retina and the reference electrode (tip ∅ ~ 30 µm) was located on the surface of the retina.…”

“…During the LERG recordings, simultaneous transretinal ERG recordings were conducted with macroelectrodes located on both sides of the retina. The recording geometry is described more in detail in 47 .…”

“…Thereby the equation (18) simplifies towhere the cGMP dark is the concentration of cGMP in dark adapted state and the J dark is the corresponding value of circulating dark current through CNG channels. In the outer segment region of rods the circulating current J ( t ) follows Ohmic relation with the voltage drop in the extracellular space across the rod outer segments, r ( t ), which is the signal registered in LERG across the outer segment layer (LERG-OS) 47,56 . The LERG-OS signal normalized by the saturation level, r max , can be considered to follow…”

Electroretinographic study of the magnetic compass in European robins

“…The transretinal voltage was recorded by ex vivo ERG [21]. The responses to light were recorded across an isolated retina placed in a closed-type perfusion chamber, as described for example in [22], photoreceptor-side down. The signals were low-pass filtered at 1000 Hz with 1 ms digitization intervals and amplified by a differential amplifier (DAM50 extracellular amplifier, World Precision Instruments, FL, USA).…”