Biomaterial Database

Retinal oxygen tension and the electroretinogram during arterial occlusion in the cat. 1995

R D Braun, and R A Linsenmeier

Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208.

OBJECTIVE Retinal oxygen tension (PO2), photoreceptor oxygen consumption (QO2), the local electroretinogram (LERG), and the vitreally recorded electroretinogram (ERG) were evaluated during retinal artery occlusion in the cat. The feasibility of supplying the retina with oxygen during occlusion by ventilation with 100% O2 was evaluated. METHODS Double-barreled oxygen microelectrodes were used to measure intraretinal PO2 and LERGs in anesthetized cats before, during, and after occlusion of a single retinal artery. Outer retinal (photoreceptor) QO2 was determined from retinal PO2 profiles. RESULTS During air breathing, occlusion obliterated the LERG b-wave and reduced the vitreal ERG by the amount expected from the area supplied by the occluded vessel. The PO2 in the entire inner retina was zero, and photoreceptor QO2 was decreased by approximately 25%. Inspiration of 100% O2 restored the b-wave amplitude to approximately 50% of normal and increased the amount of O2 reaching the inner retina. Hyperoxia could not guarantee nonzero PO2 across the entire retina in either darkness or light, but it elevated the average PO2 in the innermost 25% of the retina to more than 20 mm Hg. The b-wave amplitude must have been affected by some factor in addition to local hypoxia, because the amplitude was not correlated with inner retinal PO2 during occlusion, and a normal PO2 did not result in a normal LERG. Effects of 2 to 2.5 hours of occlusion were reversible if 100% O2 inspiration was maintained during most of the occlusion. CONCLUSIONS Ventilation with 100% O2 during occlusion increased the PO2 across most of the retina and partially restored the LERG b-wave, but the tissue near the vitreous was still sometimes anoxic. The illumination status seemed to make little difference. Inspiration of elevated O2 might be beneficial in treating retinal vascular occlusive disease, although it alone cannot completely maintain retinal function.

UI	MeSH Term	Description	Entries
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D010786	Photoreceptor Cells	Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.	Ciliary Photoreceptor Cells,Ciliary Photoreceptors,Rhabdomeric Photoreceptor Cells,Rhabdomeric Photoreceptors,Cell, Ciliary Photoreceptor,Cell, Photoreceptor,Cell, Rhabdomeric Photoreceptor,Cells, Ciliary Photoreceptor,Cells, Photoreceptor,Cells, Rhabdomeric Photoreceptor,Ciliary Photoreceptor,Ciliary Photoreceptor Cell,Photoreceptor Cell,Photoreceptor Cell, Ciliary,Photoreceptor Cell, Rhabdomeric,Photoreceptor Cells, Ciliary,Photoreceptor Cells, Rhabdomeric,Photoreceptor, Ciliary,Photoreceptor, Rhabdomeric,Photoreceptors, Ciliary,Photoreceptors, Rhabdomeric,Rhabdomeric Photoreceptor,Rhabdomeric Photoreceptor Cell
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003623	Dark Adaptation	Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.	Scotopic Adaptation,Adaptation, Dark,Adaptation, Scotopic
D004195	Disease Models, Animal	Naturally-occurring or experimentally-induced animal diseases with pathological processes analogous to human diseases.	Animal Disease Model,Animal Disease Models,Disease Model, Animal
D004596	Electroretinography	Recording of electric potentials in the retina after stimulation by light.	Electroretinographies