Biomaterial Database

Effect of hypoxia on the maintained firing rate of retinal ganglion cells. 1981

V A Alder, and I J Constable

The effect of systemic hypoxia on the maintained firing rate (MFR) of single retinal ganglion cells has been measured in the cat at a constant luminance level. Systemic hypoxia was produced by reducing the percentage of oxygen in the respiratory mixture under forced ventilation so that arterial PCO2 and pH were constant. Extracellular recordings were obtained from both X and Y retinal ganglion cells before, during, and after systemic hypoxia, with each cell acting as its own control. The MFR was unaltered by arterial PO2 levels of greater than 45 mm Hg. However, at and below this level of hypoxia the MFR was reversibly increased in 67% of the cells tested. Whether or not this increase occurred was independent of cell type or location. For arterial PO2 values of 24 to 34 mm Hg the initial increase in MFR was followed by a decrease for these cells; for PO2 values of less than 24 mm Hg the MFR showed a large initial increase followed by a complete cessation of firing. The remaining 33% of cells displayed only reduced MFR during hypoxia. The results indicate that ganglion cell function may be drastically affected by hypoxia. This may be relevant to the visual loss of a variety of retinal disorders.

UI	MeSH Term	Description	Entries
D010775	Photic Stimulation	Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.	Stimulation, Photic,Visual Stimulation,Photic Stimulations,Stimulation, Visual,Stimulations, Photic,Stimulations, Visual,Visual Stimulations
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
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000860	Hypoxia	Sub-optimal OXYGEN levels in the ambient air of living organisms.	Anoxia,Oxygen Deficiency,Anoxemia,Deficiency, Oxygen,Hypoxemia,Deficiencies, Oxygen,Oxygen Deficiencies