Regulation of retinal blood flow in health and disease

Role of nutrients in skeletal metabolism and pathology in fish — An overview

1. Selected Topics in Biochemistry Relevant to the Eye.- 2. Tears.- 3. Cornea.- 4. Aqueous, Iris-Ciliary Body, and Trabeculum.- 5. Lens.- 6. Vitreous.- 7. Retina.

/pdf/biochemistry-of-the-eye-3u93pt9aqp.pdf

Biochemistry of the Eye

Experiments designed to examine the energy requirements of neurophysiological function were performed on isolated rabbit retina. Function was altered by photic stimulation or by function-specific drugs, and the response of energy metabolism was assessed by simultaneous measurements of O2 consumption and lactate production. In other experiments, the supply of O2 or glucose was reduced and the effect on energy metabolism and electrophysiological function was observed. Energy requirements under control conditions in darkness were high, with O2 consumption (per gm dry wt) at 11.3 mumol min-1, with lactate production at 14.8 mumol min-1, and with the derived value for glucose consumption at 9.3 mumol min-1 and for high-energy phosphate (approximately P) generation at 82.6 mumol min-1. Energy reserves were small. Removing glucose abolished the b-wave of the electroretinogram (ERG) with a t1/2 of 1 min, but did not immediately affect O2 consumption or the PIII of the ERG. Removing O2 caused increases of up to 2.7-fold in glycolysis (Pasteur effect) and caused both PIII and b-wave to fail, with a t1/2 of about 5 min. Neurotransmission through the inner retina was supported almost entirely by glycolysis, as evidenced by large increases in lactate production in response to flashing light and decreases in response to transmitter blockers (2.3-fold overall change), with no change in O2 consumption. Phototransduction, on the other hand, was normally supported by oxidative metabolism. The dark current accounted for 41% of the retina's O2 consumption. With O2 reduced, the dark current was partially supported by glycolysis, which accounts (at least in part) for the large Pasteur effect. Na+ transport by NaK ATPase accounted for about half of all energy used, as evidenced by the response to strophanthidin, that is, for 49% of the oxidative energy and 58% of the glycolytic energy. The t1/2 for the turnover of intracellular Na+ was calculated from these data to be less than 1 min. Changes in temperature caused changes in the amplitude of light-evoked electrical responses of 6.5% per degree and caused changes in both O2 consumption and glycolysis of 6.8% per degree (Q10 = 1.9). A surprisingly large fraction of oxidative energy, corresponding to about 40% of the total energy generated, could not be assigned to phototransduction, to neurotransmission, to Na+ transport for other purposes, or to vegetative metabolism. We cannot account for its usage, but it may be related to the (previously reported) rapid turnover of the gamma-phosphate of retinal GTP, the function of which also remains unknown.(ABSTRACT TRUNCATED AT 400 WORDS)

https://www.jneurosci.org/content/jneuro/12/3/840.full.pdf

Energy metabolism of rabbit retina as related to function: high cost of Na+ transport

Methods are described for isolating adult rabbit retinal and maintaining it in a medium designed to resemble CSF. Morphologic, metabolic, nd electrophysiologic measurements obtained on the in vitro retinas showed that they remained in a nearly physiological state for at least 8 h, and even after 2 days in vitro they still exhibited a high level of metabolic activity and electrical responsiveness to light. Physiological activity was modified by photic stimulation, and data are presented to document changes in metabolism in response to the changes in function. The isolated retina appears to offer a number of unusual advantages for studying relationships between function and metabolism in organized mammalian central nervous tissue.

In Vitro Retina as an Experimental Model of the Central Nervous System

Two linked genes showing a similar timing of expression in mice.

Some genetic aspects of visual cell degeneration in mice.

Several years ago two metabolic poisons, iodoacetate (IAA) and azide, were found to exert upon the retina of mammals effects of outstanding selectivity for certain cells of that The two poisons had different effects, but each acted in so specific a manner that it seemed to reveal metabolic properties specifically related to the function of retinal elements. IAA, intravenously administered, affected electroretinogram and retinal excitation within less than twenty seconds after the injection, and abolished retinal function in response to illumination within a few minutes. If administered in doses higher than necessary for the block of retinal excitation, recovery was incomplete or nonexistent, and a fraction of the visual cell population or the whole population showed the signs of cell death after a few hours. These cells disintegrated and disappeared during the following days, but the other retinal cells-pigment epithelium, bipolar, and ganglionsurvived. ALide, on the other hand, exerted its most selective effect on the steady (DC-) potential across the eye and on certain slow waves of the electrical response to illumination. I t affected these potentials after injection the instant i t reached the intraocular blood. The analysis of this effect led to the conclusion that azide probably acts upon the pigment epithelium by interfering specifically with an active ion transport system of this

Studies on visual cell viability and differentiation

THE significance of glucose in the metabolism of the mammalian retina is attested by the high rate of aerobic glycolysis of this tissue in uitro (WARBURG, POSENER and NEGELEIN, 1924) and is further indicated by the extraordinary susceptibility of the visual cells to iodoacetate in vivo (NOELL, 1951, 1952). The retina is also known to respire rapidly (WARBURG, 1927) but it is undetermined to what extent this respiration is supported by glucose oxidation. As an approach to some of the questions raised by these observations we have studied the metabolic fate of glucose in the isolated retina. To provide a possible insight into the relation of glucose metabolism to retinal function, the fully developed adult rabbit retina was compared with the young tissue at 5 to 7 days after birth, a time when the retina is not yet functioning and when the rods and cones are still small, growing organelles (No~LL, 1958a, 1958b). The rabbit retina was chosen because t h i s animal has been especially useful in electrophysiological studies of the retina and because much work has been done on the effects of metabolic inhibitors upon its in uiuo functions (NOELL, 1953, 1958). The fine structure of the rabbit’s visual cells has been studied extensively by electron microscopy (DEROBERTIS and FRANCHI, 1956; DEROBERTIS, 1956; DEROBERTIS and LASANSKY, 1958) including the changes in ultrastructure resulting from iodoacetate (LASANSKY and DEROBERTIS, 1959). The distribution of key enzymes of glucose metabolism over the various layers of the rabbit’s retina has been determined by LOWRY, ROBERTS and LEWIS (1956).

Glucose catabolism of rabbit retina before and after development of visual function.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Werner K. Noell

Author Tools

Chat about Author

Papers

Two linked genes showing a similar timing of expression in mice.

Some genetic aspects of visual cell degeneration in mice.

Studies on visual cell viability and differentiation

Glucose catabolism of rabbit retina before and after development of visual function.