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Fig. 2. Electrical activities of acutely isolated SNc dopamine neurons. Spontaneous
firing activities were recorded from the cell-attached current-clamp cells
(A,Ba). Their firing activities were converted into the frequency-time graph
(A,Bb). The [Ca2+]c using fura-2 was measured from the
same cells (A,Bc). (A) The spontaneous firing activities were completely
blocked by 500 nM TTX. Note that the change in [Ca2+]c
was mirrored by the firing rate. (B) The spontaneous firing was initially
blocked by a nonspecific Ca2+ channel antagonist, 100 µM
CdCl2. But it recovered after some time even in the presence of
CdCl2. Note the persistent decreased [Ca2+]c
level after a full recovery of the spontaneous electrical activities.