Figure 7.

Raising [Ca²⁺]_o and increasing action potential duration increase train estimates of RRP size. A, Summary of the total RRP charge, as determined with 40 stimuli, 20 Hz trains recorded in the presence of 0.75 mm Ca²⁺, 2 mm Ca²⁺, 4 mm Ca²⁺, or 4 mm Ca²⁺ plus 100 μm 4-AP, expressed as a percentage of the sucrose estimates of RRP size performed in the same neurons; ^*p < 0.002 and ^**p < 0.042 compared with sucrose estimates of RRP size (n = 5-14 in each condition). B, The areas of EPSCs were measured at various times after high-frequency stimulation in 0.75 mm Ca²⁺ (filled triangles), 2 mm Ca²⁺ (filled circles), and 4 mm Ca²⁺ (open circles) and compared with the areas of original responses (n = 4-5 for each point). Recovery from inhibition was fit with a double exponential; weighted τ = 3.49 s (0.75 mm Ca²⁺), 1.37 s (2 mm Ca²⁺), and 1.82 s (4 mm Ca²⁺). Fits were constrained to a maximum of 100%. Error bars represent SEM.