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. Author manuscript; available in PMC: 2010 May 11.
Published in final edited form as: Neuroscience. 2001;107(1):59–69. doi: 10.1016/s0306-4522(01)00293-7

Fig. 5.

Fig. 5

Suppressing both fast synaptic transmission and VGCCs prevents internal Ca2+ release evoked by brief bursts. (A) In this experiment CNQX (20 μM) alone did not block Ca2+ release evoked by bursts of mossy fiber stimulation (20 pulses at 100 Hz) while in current-clamp mode. When the cell was voltage-clamped to ~−75 mV (still in the presence of CNQX), however, there was little voltage escape (see voltage trace), and consequently, internal Ca2+ release was completely blocked, providing further support for the hypothesis that a threshold rise in cytosolic [Ca2+] is necessary for internal release. (B) Summary graph showing that CNQX (20 μM) suppressed Ca2+ release with brief bursts of stimulation (<20 pulses), and totally blocked release when cells were voltage-clamped to rest (n = 9). When long trains of stimulation (50 pulses) were given, however, CNQX had little effect on internal release when in current-clamp mode (CC), and only suppressed release when in voltage-clamp mode (VC) (n = 9).