This project is designed to elucidate aspects of retinal function concerned with ionic homeostasis, the role of glial cells, and the generation of the electroretinogram (ERG). Our specific objectives are: (1) To determine the sources and sinks of current underlying components of the ERG--by applying a quantitatively thorough current-source-density (CSD) analysis; (2) To determine the sources and sinks of changes in the extra-cellular concentration of ions--by applying a newly-developed technique of ion-source-density (ISD) analysis; (3) To assess the cellular origins, whether neural or glial, of ERG components and extracellular ionic changes--by experiments with selected pharmacological agents that may serve to dissociate various responses; (4) To specify the resting levels of, and the light-evoked changes in, the concentrations of various ions in the retina--by measurements with ion-selective microelectrodes (ISM's) in vivo and in vitro; (5) To examine characteristics of the distal K-increase (OPL K-increase) and determine its relationship to the b-wave--by comparative analyses of both responses and the effects of stimulus variables and pharmacological agents; and (6) To investigate the ability of Muller cells in whole retinas to spatially buffer changes in [K+]. The proposed experiments will aid in clarifying questions concerning the origin or ERG components, and thereby further the interpretative utility of the ERG in clinical ophthalmological diagnosis. This work will also contribute to our understanding of glial cells, and of the role and influence of the extracellular micro-environment in neuronal-glial interactions.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003526-09
Application #
3257873
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1980-01-01
Project End
1991-06-30
Budget Start
1988-07-01
Budget End
1989-06-30
Support Year
9
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Georgia
Department
Type
Schools of Arts and Sciences
DUNS #
City
Athens
State
GA
Country
United States
Zip Code
30602
Karwoski, C J; Xu, X (1999) Current source-density analysis of light-evoked field potentials in rabbit retina. Vis Neurosci 16:369-77
Wilson, M T; Farmer, M A; Karwoski, C J (1998) Ultrastructure of the frog retina after high-pressure freezing and freeze substitution. J Microsc 189:219-35
Xu, X; Karwoski, C J (1997) The origin of slow PIII in frog retina: current source density analysis in the eyecup and isolated retina. Vis Neurosci 14:827-33
Karwoski, C J; Xu, X; Yu, H (1996) Current-source density analysis of the electroretinogram of the frog: methodological issues and origin of components. J Opt Soc Am A Opt Image Sci Vis 13:549-56
Xu, X; Karwoski, C (1995) Current source density analysis of the electroretinographic d wave of frog retina. J Neurophysiol 73:2459-69
Xu, X; Karwoski, C J (1994) Current source density (CSD) analysis of retinal field potentials. I. Methodological considerations and depth profiles. J Neurophysiol 72:84-95
Xu, X; Karwoski, C J (1994) Current source density analysis of retinal field potentials. II. Pharmacological analysis of the b-wave and M-wave. J Neurophysiol 72:96-105
Warren, G L; Lowe, D A; Hayes, D A et al. (1993) Excitation failure in eccentric contraction-induced injury of mouse soleus muscle. J Physiol 468:487-99
Shaw, A P; Collazo, C R; Easterling, K et al. (1993) Circadian rhythm in the visual system of the lizard Anolis carolinensis. J Biol Rhythms 8:107-24
Huang, B; Karwoski, C J (1992) Light-evoked expansion of subretinal space volume in the retina of the frog. J Neurosci 12:4243-52

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