Elevation of intracellular ca(2+) concentration induced by hypoxia in retinal ganglion cells

• Published in: Japanese journal of ophthalmology 2007-05, Vol.51 (3), p.175
• Main Authors: Sasaki, Tsugihisa, Kaneko, Akimichi
• Format: Article
• Language: English
• Subjects: 6-Cyano-7-nitroquinoxaline-2,3-dione - pharmacology; Animals; Bepridil - pharmacology; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Dendrites - drug effects; Dendrites - metabolism; Dendrites - pathology; Disease Models, Animal; Excitatory Amino Acid Antagonists - pharmacology; Glutamic Acid - metabolism; Hypoxia - metabolism; Hypoxia - pathology; Hypoxia - prevention & control; Intracellular Fluid - metabolism; Microscopy, Confocal; Microscopy, Fluorescence; N-Methylaspartate - analogs & derivatives; N-Methylaspartate - pharmacology; Nifedipine - pharmacology; Poisons - pharmacology; Rats; Rats, Inbred Lew; Retinal Ganglion Cells - metabolism; Retinal Ganglion Cells - pathology; Sodium Channel Blockers - pharmacology; Sodium-Calcium Exchanger - drug effects; Sodium-Calcium Exchanger - metabolism; Tetrodotoxin - pharmacology; Valine - analogs & derivatives; Valine - pharmacology
• ISSN: 0021-5155
• DOI: 10.1007/s10384-006-0426-x

To analyze the mechanism of hypoxia-induced changes of the intracellular Ca(2+) concentration ([Ca(2+)](i)) in retinal ganglion cells (RGCs). 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. The retrograde staining method filled the RGCs selectively. Fifteen minutes of hypoxic conditions induced an increase in [Ca(2+)](i) in the RGCs (Delta0.13 +/- 0.03, n = 23). Application of 60 microM DL-2-amino-5-phosphonovaleric acid partially blocked the hypoxia-induced [Ca(2+)](i) increase in dendrites (Delta0.03 +/- 0.02, n = 4, P < 0.05) but not in the somata (Delta0.12 +/- 0.02, n = 9). The RGC dendrites showed a further increase in [Ca(2+)](i) after being switched back to an oxygenated solution (Delta0.14 +/- 0.04, n = 4). Neither 6-cyano-7-nitroquinoxaline-2,3-dione disodium, DL: -threo-beta-benzyloxyaspartate, nifedipine, nor bepridil inhibited the hypoxia-induced [Ca(2+)](i) increase. A Ca(2+)-free superfusion prevented the hypoxia-induced [Ca(2+)](i) increase in the somata (Delta0.07 +/- 0.02, n = 5, P < 0.05) but not in the dendrites (Delta0.16 +/- 0.005, n = 4). The mechanism of the hypoxia-induced increase in [Ca(2+)](i) differs between somata and dendrites. The N-methyl-D-aspartate channel of dendrites seems to be the main route of Ca(2+) influx.