Figure 4.
Exocytosis of glutamate and activation of neurons postsynaptic to the Mb terminal are required for modulation of ICa. A, Consecutive ICa traces recorded from an axotomized Mb terminal in slice preparation in response to voltage ramps 4 min apart in the presence of intracellular Exo1 (50 μm). The exocytosis inhibitor Exo1 prevented the leftward shift of the second ramp I-V (red) compared with the control ramp I-V (black). B, Consecutive ICa traces recorded from an axotomized Mb terminal in slice preparation, in response to voltage ramps 3 min apart in the presence of iGluR antagonists NBQX (25 μm) and d-AP5 (50 μm). The antagonists prevented the leftward shift of the second trace (red) from control (black). There are spontaneous outward GABAergic IPSCs at depolarized potentials in the absence of PTX.