Figure 7. DHPG-induced potentiation of NMDA currents at resting potential, in physiological concentration of Mg2+.
A) Left - Representative NMDA (100µM)-induced current, without (NMDA) or with (Mg2+) extracellular Mg2+ (0.7 mM), co-applied with DHPG (50 µM). Right – Mean ± SEM current density recorded in 0.7 mM Mg2+, from n = 21 neurons in 3 independent experiments. Wilcoxon matched-pairs signed rank test. B) Current density-voltage relationship (-80 -> +60 mV within 100ms every 5s) performed as illustrated in (a) during NMDA application (at the plateau response) without (blue) or with 0.7 mM Mg2+ (black) co-applied with DHPG (red). Mean from n = 8-10 neurons per condition. C) Projection of spontaneous calcium transients, recorded during 2 min and 15 sec, in Mg2+ (0.7mM) at resting potential of neurons in a representative field of view. Top: all events for the entire field of view. Bottom: small non-propagating calcium transients from the white square in the top image, for three consecutive acquisitions. Left: basal. Middle: basal + DHPG (50 µM). Right: basal + DHPG (50 µM) + AP5 (50 µM). D) Number of calcium transients recorded in the whole field of view before (CT) and after sequential application of DHPG and AP5. E) GCaMP6s fluorescence fluctuation during small non-propagating calcium transients, Mean ± SEM of 91 and 94 traces, before (black) and after (red) DHPG application, measured on 10, identical, AP5-sensitive ROI; F) Mean area under curve (AUC) of calcium transients. Each bar of the histogram is the Mean ± SEM of all AUC traces recorded in the whole field of view before and after DHPG application for 2 min and 15 seconds in both conditions. Statistics: Unpaired t test.