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Abstract #18214 Published in IGR 9-2
Elevation of intracellular Ca2+ concentration induced by hypoxia in retinal ganglion cells
Sasaki T; Kaneko AJapanese Journal of Ophthalmology 2007; 51: 175-180
PURPOSE: To analyze the mechanism of hypoxia-induced changes of the intracellular Ca2+ concentration (Ca2+i) in retinal ganglion cells (RGCs). METHODS: Fluo-3 was applied to the cut edge of the optic nerve of 6-week-old rats. The retina was sliced, and the Ca images were captured. A hypoxic condition was created by superfusing the retinal slice with an oxygen/glucose-deprived solution. RESULTS: The retrograde staining method filled the RGCs selectively. Fifteen minutes of hypoxic conditions induced an increase in Ca2+i in the RGCs (Δ0.13 ± 0.03, n = 23). Application of 60 μm DL: -2-amino-5-phosphonovaleric acid partially blocked the hypoxia-induced Ca2+i increase in dendrites (Delta0.03 ± 0.02, n = 4, P < 0.05) but not in the somata (Δ0.12 ± 0.02, n = 9). The RGC dendrites showed a further increase in Ca2+i after being switched back to an oxygenated solution (Δ0.14 ± 0.04, n = 4). Neither 6-cyano-7-nitroquinoxaline-2,3-dione disodium, DL: -threo-β-benzyloxyaspartate, nifedipine, nor bepridil inhibited the hypoxia-induced Ca2+i increase. A Ca2+-free superfusion prevented the hypoxia-induced Ca2+i increase in the somata (Delta0.07 ± 0.02, n = 5, P < 0.05) but not in the dendrites (Δ0.16 ± 0.005, n = 4). CONCLUSIONS: The mechanism of the hypoxia-induced increase in Ca2+i differs between somata and dendrites. The N-methyl-D: -aspartate channel of dendrites seems to be the main route of Ca2+ influx.
Dr. T. Sasaki, Department of Ophthalmology, Kanazawa University School of Medicine, Kanazawa, Ishikawa, Japan
Classification:
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
3.6 Cellular biology (Part of: 3 Laboratory methods)