Fig. 2.

VDCC-mediated Ca²⁺ influx stimulates exocytosis and inhibits endocytosis more efficiently than a uniform [Ca²⁺]_i increase.A, Ca²⁺-dependent glutamate release after 2 min evoked by KCl (squares), 4-AP (circles), or ionomycin (IONO;triangles) is plotted against the stimulated [Ca²⁺]_i increase for each agent measured using fura-2. [Ca²⁺]_i was sampled after 20 sec stimulation. For all experiments,n = 3–7 (±SEM). B, Retrieval efficiency for increasing concentrations of KCl (squares), 4-AP (circles), or ionomycin (triangles) is plotted against evoked [Ca²⁺]_i increases for each agent. For all experiments, n = 3–7 (±SEM). In bothA and B, error bars are smaller than thesymbols.