A, sample traces of EPP responses upon 30 Hz stimulation were shown. B, control NMJs displayed depression whereas Cplx 1 KO NMJs showed strong synaptic facilitation. Values are means ± SEM; n= 22–29 NMJs from 7 mice for each genotype. C, sample traces of paired-pulse (10 ms apart) responses from control, Cplx 1 KO and BAPTA-AM treated Cplx 1 KO NMJs are shown. D, stronger paired-pulse facilitation was observed at Cplx 1 KO NMJs (Ctrl vs. Cplx 1 KO, 102.1 ± 0.7 vs. 158.4 ± 10.2%; ***P < 0.0001, Student's t test; n= 16–19 NMJs from 3–5 mice for each genotype). The calcium chelator BAPTA-AM significantly reduced the paired-pulse facilitation at Cplx 1 KO NMJs (Ctrl with BAPTA-AM: 97.0 ± 1.8%; Cplx 1 KO with BAPTA-AM: 132.8 ± 2.6%; *P= 0.018, Student's t test; n= 19–20 NMJs from 3–5 mice for each group).