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B.A. Ekesten, P. Gouras; Light-adaptation and Recovery of Rod and Cone Function in the Superfused Murine Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4164.
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Purpose: The superfused murine retina provides better access and more stable recording conditions than the mouse eye in vivo. It also facilitates recording from different areas, which aids in the study of topographical differences between the inferior, UV-cone rich area and the superior retina, which contains more M-cones. We have studied how rod and cone responses recover after light adaptation. Methods: Eyecups from normal C57BL mice were superfused with oxygenated Dulbecco's Modified Eagle's Medium with 0.1 mM glutamate. Local ERGs and single ganglion cell responses from different areas of the retina were examined in response to UV and green flashes. Strong background lights were employed to light adapt the retina. Responses were amplified and averaged by a computerized data acquisition system. Results: Responses to UV and mid-spectral stimuli could be obtained from the eyecups for many hours. The UV-stimuli affect the UV-cones and to a lesser extent rods and possibly M-cones. Mid-spectral, green, stimuli affect only rods and M-cones. When the retina is adapted with long wavelength light, the rods and M-cones are desensitized but the UV cones are not. This reveals the ERG and ganglion cell responses from UV-cones alone. Rod and M-cone responses recover responsiveness in 10-15 minutes from such backgrounds. When the retina is more strongly light-adapted with white light, responses to mid-spectral stimuli no longer recover but UV-cone responses recover completely. Conclusions: The rapid recovery of the rod responses to moderate adapting lights suggests that neural adaptation of the rod mechanism is relatively normal in this preparation. The permanent loss of rod responses after stronger adapting lights suggests that rhodopsin regeneration is abnormal. The ability of UV-cones to tolerate all adapting lights suggests that they may have another source of photopigment. The absence of all responses to mid-spectral stimuli may reflect areas without M-cones and is evidence against global co-expression of opsins.
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