Light-evoked oxygen responses in the isolated toad retina

Haugh-Scheidt, Laura; Griff, Edwin R.; Linsenmeier, Robert A.

doi:10.1016/s0014-4835(95)80060-3

Cited by 25 publications

(26 citation statements)

References 17 publications

(16 reference statements)

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“…3), the location with the highest concentration of mitochondria in the retina. The present findings are thus consistent with the previous suggestion that photoreceptor cells are the principal consumers of energy in the retina (Haugh-Scheidt et al, 1995;Demontis et al, 1997). However, until a more thorough analysis of the sources and sinks of acid flux in the retina is performed, the present findings cannot be considered conclusive.…”

Section: Relationship Of the Clock Ph And Energetic Metabolismsupporting

confidence: 94%

Circadian Clock Regulation of pH in the Rabbit Retina

Dmitriev

Mangel

2001

J. Neurosci.

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Although it is generally accepted that the acid-base ratio of tissue, as represented by the pH, is strictly regulated to maintain normal function, recent studies in the mammalian nervous system have shown that neuronal activity can result in significant shifts in pH. In the mammalian retina, many cellular phenomena, including neuronal activity, are regulated by a circadian clock. We thus investigated whether a clock regulates retinal pH, using pH-sensitive microelectrodes to measure the extracellular pH (pH o ) of the in vitro rabbit retina in the subjective day and night, that is, under conditions of constant darkness. These measurements demonstrated that a circadian clock regulates the pH o of the rabbit retina so that the pH o is lower at night than in the day. This day/night difference in retinal pH o was observed when the rabbits were maintained on a normal light/dark cycle and after they were maintained on a light/dark cycle that was phase-delayed by 9 hr. Continuous recordings of retinal pH o around subjective dusk indicated that the change from daytime to nighttime pH o is relatively fast and suggested that the clock that regulates pH o is located in the retina. The lowest pH o recorded in the retina in both the day and night was in the vicinity of the inner segments of photoreceptor cells, supporting the idea that photoreceptors serve as the primary source of protons. The circadian-induced shift in pH o was several times greater than light-induced pH o changes. These findings suggest that a circadian clock in the mammalian retina regulates retinal pH.

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Section: Relationship Of the Clock Ph And Energetic Metabolismsupporting

confidence: 94%

Circadian Clock Regulation of pH in the Rabbit Retina

Dmitriev

Mangel

2001

J. Neurosci.

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“…The decrease in oxygen utilization with light has been found in all vertebrates that have been studied, including frog (Sickel, 1972), toad (Haugh-Scheidt et al, 1995a; Kimble et al, 1980), and rabbit (Ames et al, 1992), animals which are not otherwise considered in this review. The time course of the change in metabolism can be studied with a microelectrode placed near the inner segments while the illumination is changed, as shown in Figure 7.…”

Section: Fundamentals Of O2 Supply To the Retinamentioning

confidence: 99%

Retinal oxygen: from animals to humans

Linsenmeier

Zhang

2017

Progress in Retinal and Eye Research

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This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.

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“…When the retina was in low [Na+], a light-evoked decrease in retinal PO 2 was measured in the outer retina (Haugh-Scheidt et al, 1995); however, the magnitude of the change was smaller than the light-evoked increase in PO2 in normal [Na+]. In low [Na+], the PO 2 profiles measured in light adaptation were not noticeably different from the profiles measured in dark adaptation, and the parameter values were not significantly different.…”

Section: Lowered Extracellular [Na +]mentioning

confidence: 84%

“…The QO 2 in the photoreceptor layer of the retina, in lowered [Na+], was not significantly greater in light as compared to darkness. This result was surprising given the consistent light-evoked PO2 decrease in the lowered [Na+] condition (Haugh-Scheidt et al, 1995), which indicated a QO 2 increase in the photoreceptors. The -low [Na ÷] condition, maintained for as long as necessary to measure profiles in light and dark (about 2 hr), may not maintain the retina in a stable state, judged by the slow increase in retinal PO 2 often observed in low [Na+].…”

Section: Retinal Q02mentioning

confidence: 88%

Oxygen consumption in the isolated toad retina

Haugh-Scheidt

Linsenmeier

Griff

1995

Experimental Eye Research

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Retinal 02 utilization was studied to identify the 02 consuming processes in the retina and the spatial distribution of those processes. Neural retina, retinal pigment epithelium and choroid were dissected from the toad eye and superfused with an oxygenated Ringer's solution. Double-barreled microelectrodes were used to measure 02 and local voltage simultaneously within the retina in both light and dark adaptation. The profile of PO 2 was measured during a withdrawal of the electrode tip across the retinal pigment epithelium and through the neural retina. The PO 2 decreased through the distal retina, reaching a minimum in the inner segment or outer nuclear layer, and then increased steadily through the proximal retina. From fitting PO 2 profiles measured in the dark-adapted retina to a three-layer diffusion model, 02 consumption was found to be 1"0+0"4 and 0'4+0-3 ml 02 (100 g min) -x in the outer and inner halves of the retina, respectively. Light decreased consumption in both halves of the retina. In steady illumination (500 nm) that saturated the ERG b-and c-waves, 02 utilization decreased significantly to 48 % and 68 % of the dark values in the outer and inner retina, respectively. When Na ÷ was removed from the superfusate to inhibit the photoreceptor Na+/K ÷ pump, 02 consumption in the outer retina decreased by about the same amount as in light, but Oz consumption in the inner retina was not significantly affected.

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Light-evoked oxygen responses in the isolated toad retina

Cited by 25 publications

References 17 publications

Circadian Clock Regulation of pH in the Rabbit Retina

Circadian Clock Regulation of pH in the Rabbit Retina

Retinal oxygen: from animals to humans

Oxygen consumption in the isolated toad retina

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