Figure 1.

Increased osmolarities permit less dye release. (A) Percent of FM1–43 that escapes per quantum of transmitter released by hypertonic stimulation, relative to dye released per quantum with action potentials, as a function of hypertonicity. Figure presents data from 780 synapses in 8 experiments on conventional and microdot cultures; error bars indicate one SEM. The smooth line is given by

where h is the hypertonicity in osmolars. See text for discussion of equation. Dye release was determined for hypertonic and action potential stimulation in the same synapses. (B) Image of field after loading as described in text (Left) and after prolonged stimulation to release all dye in synaptic vesicles (Right). Synapses appear as small black dots (Left) that are no longer visible (Right).