Physiological investigations of glia-neurone interactions will be continued using the retina of the honeybee drone as a model preparation. This preparation has useful features that make possible experiments that have not yet been performed on mammalian preparations. These features include: (1) The retina is composed of essentially one type of neurone, the photoreceptor cells, which can be stimulated by light, and one type of glial cell. (2) Activities of intracellular ions, particularly K+ and Na+, can be measured with ion-sensitive microelectrodes, in both photo-receptors and glial cells. (3) Ionic and metabolic interactions between glial cells and photoreceptors have been demonstrated. (4) The kinetics of oxygen consumption by the photoreceptors, after a singe flash of light, can be measured. Investigation of the mechanisms by which K+ enters the glial cells when the photoreceptors are stimulated will be continued. Measurements will be made with intracellular Cl- sensitive microelectrodes, and a quantitative synthesis will be attempted of the measured changes in K+, Na+ and Cl- in the photoreceptors, glial cells and extracellular space. The possibility that some of the intracellular Na+, K+ and Cl- is 'bound' and not detected by ion-sensitive electrodes will be investigated by measuring total concentrations of these elements with an electron beam microprobe. To measure the volume of the extra-cellular space a new method will be used in which the diffusion of extra-cellular probe ions through a slice of retina will be measured with ionsensitive electrodes outside the tissue. This method will also permit an investigation of possible interactions between fixed extracellular charges and mobile ions. Control of mitochondrial respiration in functioning tissue will be investigated by looking for an increase in ATP concentration after a brief stimulus.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003504-06
Application #
3257836
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1981-02-01
Project End
1987-01-31
Budget Start
1986-02-01
Budget End
1987-01-31
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Geneva
Department
Type
DUNS #
481076537
City
Geneva
State
Country
Switzerland
Zip Code
CH-1211
Poitry-Yamate, C; Tsacopoulos, M (1991) Glial (Muller) cells take up and phosphorylate [3H]2-deoxy-D-glucose in mammalian retina. Neurosci Lett 122:241-4
Coles, J A; Schneider-Picard, G (1989) Amplification of small signals by voltage-gated sodium channels in drone photoreceptors. J Comp Physiol A 165:109-18
Coles, J A; Orkand, R K; Yamate, C L (1989) Chloride enters glial cells and photoreceptors in response to light stimulation in the retina of the honey bee drone. Glia 2:287-97
Karwoski, C J; Coles, J A; Lu, H K et al. (1989) Current-evoked transcellular K+ flux in frog retina. J Neurophysiol 61:939-52
Coles, J A; Schneider-Picard, G (1989) Increase in glial intracellular K+ in drone retina caused by photostimulation but not mediated by an increase in extracellular K+. Glia 2:213-22
Coles, J A (1989) Functions of glial cells in the retina of the honeybee drone. Glia 2:1-9
Astion, M L; Coles, J A; Orkand, R K et al. (1988) K+ accumulation in the space between giant axon and Schwann cell in the squid Alloteuthis. Effects of changes in osmolarity. Biophys J 53:281-5
Coles, J A (1988) Bias current modifies the selectivity of liquid membrane ion-selective microelectrodes. Pflugers Arch 411:339-44
Munoz, J L; Coles, J A (1987) Quartz micropipettes for intracellular voltage microelectrodes and ion-selective microelectrodes. J Neurosci Methods 22:57-64
Astion, M L; Coles, J A; Orkand, R K (1987) Effects of bicarbonate on glial cell membrane potential in Necturus optic nerve. Neurosci Lett 76:47-52

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