Figure 7.

Glutamate-induced inward currents in passive and outwardly rectifying cells. Passive and outwardly rectifying astrocytes show a different sensitivity to glutamate receptor and transporter blockers. A, Current traces elicited by local application of 1 mm glutamate in a passive astrocyte under control conditions (500 nm TTX, 100 μm CdCl₂, 50 μm AP5, 20 μm bicuculline, 20 μm strychnine) after blockade of AMPA receptors with 50 μm CNQX and after additional blockade of glutamate transporters by 300 μm DHK plus 50 μm THA. B, Same experimental protocol in an outwardly rectifying astrocyte. C, Point-by-point subtraction of the recordings depicted in A reveals different kinetics of the DHK-THA-sensitive and CNQX-sensitive currents. D, Reduction of glutamate current induced by receptor (CNQX) and transporter (THA+DHK) blockers in different types of astrocytes (data are given as mean ± SE).