Figure 6. The effect of HS on facilitation is independent of the concentration of intracellular Ca²⁺.

A, chelation of intracellular Ca²⁺ by BAPTA reduced transmitter release without affecting the quantal size. B, effect of HS on facilitation remained unchanged when intracellular Ca²⁺ was chelated by BAPTA. Columns represent the ratios between m with and without HS at the same recording site. The horizontal line indicates the level at which there would be no effect of HS (HS/NS = 1). C, effect of HS on facilitation with a physiological concentration of Ca²⁺. D, effect of HS on facilitation after intracellular Ca²⁺ was chelated by BAPTA. B, C and D show results from 8 experiments.