Potassium-stimulated calcium uptake in astrocytes and its potent inhibition by nimodipine

✍ Scribed by Dr. L. Hertz; A. S. Bender; D. M. Woodbury; H. S. White

• Book ID: 102908432
• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 627 KB
• Volume: 22
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490220215

✦ Synopsis

Elevation of the extracellular potassium concentration above its "resting" level of 5.4 mM stimulated uptake of 45Ca2+ in primary cultures of astrocytes. This effect was only observed when cells were exposed to excess potassium shortly after their exposure to 45Ca2+ and was potently inhibited (IC5,, -3 nM) by the calcium channel blocker nimodipine. In contrast, nimodipine exerted little effect on unstimulated basal uptake of 45Ca2+. These findings suggest that the therapeutic benefit of calcium channel blockers in epilepsy may result in part from the ability of these drugs to prevent calcium entry into astrocytes during seizures when the extracellular potassium is elevated four-to fivefold above normal.

ing sites for these drugs have been observed in many different brain preparations (Ehlert et al.