Differences between different secretagogues for stimulation of different amounts of secreted catecholamines are shown for dopamine (DA), norepinephrine (NE), and epinephrine (Epi) in panels A, B, and C, respectively. Secretagogue-stimulated catecholamine amounts were calculated from the measured catecholamine levels in the media of secretagogue-treated chromaffin cells, with subtraction of the basal levels of catecholamines secreted in the absence of secretagogue. One-way ANOVA analyses indicated significant differences among pairs of secretagogues for stimulated catecholamine secretion, shown by the lines with *p < 0.05.