Figure 4.

DOC2B^D218,220N enhances secretion without priming. A, B, exocytotic response of chromaffin cells stimulated directly with a high-intensity UV flash under conditions of low preflash calcium, as opposed to the standard paradigm, in which preflash [Ca²⁺]_i was elevated to ∼300 nm for 30 s. A, Top graph, Averaged [Ca²⁺]_i during flash photolysis of caged calcium. Error bars represent SEM. Bottom graph, Averaged capacitance change (ΔC_m) during 5 s stimulation of cells expressing DOC2B^D218,220N (red; n = 8), DOC2B^wt (blue; n = 11), or EGFP (black, n = 10). B, Averaged capacitance change during the exocytotic burst (left) and sustained phase (right) for cells expressing DOC2B^D218,220N (red), DOC2B^wt (blue), or EGFP (black). *p < 0.05.