Figure 4.

Ca²⁺-dependent decrease of [³H]-STX binding capacity in A23187- and TG-treated adrenal chromaffin cells. (A) Cells were treated for 24 h with DMSO, 1 μM A23187 or 100 nM TG in the absence (none) or presence of 5 mM EGTA or 50 μM BAPTA-AM, washed, and subjected to [³H]-STX binding assay. Mean±s.e.mean (n=5). ^*P<0.05, significant decrease by A23187 or TG within each cell group. (B) Cells were exposed to DMSO, 1 μM A23187 or 100 nM TG for the first 24 h, then treated with or without 50 μM BAPTA-AM in the continuous presence of DMSO, A23187 or TG for up to 48 h, and used for [³H]-STX binding assay. Mean±s.e.mean (n=3). ^*P<0.05, compared with A23187 or TG alone.