EXTRACELLULAR GLUCOSE DEPENDENCE OF RHODOPSIN REGENERATION IN THE EXCISED MOUSE EYE

To study the process of rhodopsin regeneration a superfused excised whole eye preparation of the albino mouse was developed. With this preparation, complete regeneration could be observed after each of the first two illuminations (bleaching 15-20%), and incomplete regeneration after a third illumination. Regeneration was minimal at extracellular glucose concentrations of 0 or 1 mm with improved regenerations at higher concentrations. Maximum regenerations were observed at glucose concentrations of 4-10 mm. First-bleach regenerations were as follows: 0 mm glucose, 20%; 1 mm, 8%; 2 mm, 45%; 3 mm, 82%; 4 mm, 115%; 5·1 mm, 121%; 7 mm, 120%; and 10 mm, 126%. The effects of reduced glucose were reversible. After an initial bleach with 0 or 1 mm extracellular glucose that exhibited minimal regeneration, the re-addition of glucose (5·1 mm) restored the ability of the eye to regenerate rhodopsin following a second bleach, but only to the level prior to that bleach. Mitochondrial substrates fumarate (10 mm) or pyruvate (10 mm) partly substituted for glucose, exhibiting first-bleach regenerations of 56 and 85%, respectively. © 1992.