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. 2016 May 29;594(13):3705–3727. doi: 10.1113/JP272415

Figure 7. Co‐expression of TARP γ‐2 enhances a pedestal current that is resistant to NBQX .

Figure 7

A and B, inward currents evoked by ten 2 ms applications of 10 mm glutamate (arrows) repeated every 10 ms to outside‐patches from tsA201 cells expressing GluA1 and GluA2 either without (A) or with co‐expression of the type I TARP, γ‐2 (B). If deactivation is not complete between pulses, there is still a residual current that persists at the start of the next application. We refer to this current as the pedestal current. In the absence of γ‐2, the currents decay almost completely before the next application, and there is only a small inward pedestal current during the train (A). With γ‐2 co‐expression (B), the decay of the current is slower and bi‐exponential, and the relative size of the pedestal current is enhanced. C, the size of the pedestal current is increased when the applications are repeated at 6 ms intervals, where the decay of the responses is less complete between applications, owing to the presence of the TARP‐associated slow component. D and E, trains of responses in two other patches expressing GluA1 and GluA2 without or with γ‐2. In the absence of γ‐2 co‐expression (D), both the peak and pedestal currents are abolished by the continuous application of 200 nm NBQX. When γ‐2 was co‐expressed (E), the peak current (maximal inward current evoked by the first application minus the pedestal current) is inhibited by ∼75%, whereas the enhanced pedestal current is inhibited by ∼40%. F, mean percentages of the pedestal current (expressed as a percentage of the maximal current evoked by the first control application in the same patch) in the absence and presence of 200 nm NBQX in patches from cells that did not and did express TARP γ‐2. The results are from seven and 10 patches. Bars indicate SEM. *Both control and NBQX values without TARP γ‐2 were significantly different from the corresponding values with TARP γ‐2 (two‐way ANOVA, P < 0.0001). ‡The means with and without NBQX were not significantly different; however, the percentage inhibition of the pedestal current without γ‐2 (98.4 ± 1.0%, n = 7) was significantly different from zero (P < 0.0001, Student's two‐tailed t test), whereas the corresponding inhibition with γ‐2 (22.8 ± 11.3%, n = 10) was not (P = 0.075).