Choline substitution for sodium triggers glutamate and adenosine release from rat hippocampal slices.

Substituting choline for sodium resulted in an extracellularly recorded transient depolarization and increased efflux of glutamate and adenosine from rat hippocampal slices. The depolarization was blocked by a combination of NMDA and non-NMDA antagonists, MK-801 (10 microM) and 6,7-dinitroquinoxaline-2,3-dione (DNQX, 50 microM). Adenosine release was blocked by MK-801 alone. These data suggest that glutamate released as a result of the sodium removal acts at NMDA and non-NMDA glutamate receptors to trigger the depolarization and acts at NMDA receptors to trigger adenosine release.