Figure 5.

HFS induces glutamate release in primary astrocyte cultures. (A) Immunocytochemistry of a primary astrocytic culture revealed that > 98% of the cells were astrocytes as shown by GFAP staining. (B) High frequency stimulation (HFS) of the astrocytic culture (100Hz, 100μs pulse width, 300μA) for 10 seconds resulted in an increase in extracellular glutamate as measured by an enzyme-linked glutamate sensor. Astrocytic glutamate release was both frequency (C) and intensity (D) dependent. The stimulating electrode and the glutamate sensor electrode were positioned within ∼100μm of each other.