Figure 3.

Postsynaptic intracellular Ca²⁺ rise is necessary to eCB-LTD. (A) The membrane-permeant Ca²⁺-chelator BAPTA-AM markedly reduced the fEPSP (45.5 ± 7.2% of baseline in BAPTA-AM, n = 4, not shown), suggesting that this concentration effectively buffered intracellular Ca²⁺. Preincubation of slices with BAPTA-AM (50 μM) prevented eCB-LTD: fEPSP was 99.6 ± 7.0% of baseline at 60 min, n = 6, P < 0.05 in BAPTA-AM-treated slices vs. control without BAPTA-AM. (B) In whole-cell experiment, filling the recording pipettes with BAPTA (20 mM) also suppressed eCB-LTD: eEPSC was 153.4 ± 26.6% of baseline at 30 min in the presence of intracellular BAPTA, n = 5, P < 0.05 vs. control without BAPTA.