Figure 3.

CF stimulation elicits both glutamate transporter currents and AMPA receptor currents in Bergmann glia. (A) Bergmann glia response to CF stimulation is all-or-none and blocked by a combination of NBQX (10 μM), D-CPP (5 μM), SR-95531 (5 μM), and THA (300 μM). Each point represents the average of three consecutive responses. Holding potential was −90 mV. At the first asterisk the stimulation intensity was decreased to 10 μA, below the threshold for the response. The stimulation intensity was then increased in steps of 20 μA, with three responses recorded at each intensity. The response returned at 70 μA and did not increase in amplitude when the intensity was increased further (up to 130 μA). A stimulation intensity of 110 μA was maintained during the rest of the experiment except at the second asterisk where the threshold was again tested. (B) Averaged Bergmann glial responses to stimuli of different intensities. (C) The rapid component of the current is blocked by NBQX (10 μM) and the remaining slow component is blocked by THA (300 μM). (D) Comparison of the kinetics of the AMPA receptor and transporter currents evoked by CF stimulation. The AMPA receptor current was obtained by subtracting the response in the presence of NBQX from the control response. (E) CdCl₂ (30 μM), but not dihydrokainate (300 μM), blocked the NBQX-insensitive current. All traces are averages of 3–5 consecutive responses and were recorded from the same Bergmann glial cell. KNO₃-based internal solution.