Proportional relation between quantal size and vesicle volume for control cells (A, B), l-dopa-treated cells (C, D), and reserpine-treated cells (E, F). A, C, and E show data points from all cells in a group; B, D, and F show data points from individual cells only. Straight lines through the origin were fitted to the data points. The slopes and correlation coefficients are indicated on the panels.