Figure 3.

PMA increases the size of the RRP detected optically. A, Synapses were loaded with FM2-10 by depolarization with a 47 mm K⁺ solution for 90 s. After dye washout, the synapses were imaged during a 15 s sucrose application followed by multiple rounds of 90 mm K⁺ application. After a 5 min wash, the same synapses were treated with 1 μm PMA or 4α-PMA for 2 min. After another 5 min wash to remove residual PMA, these synapses were subjected to a second round of 47 mm K⁺ loading and subsequent destaining. B, C, Sample experimental traces showing the average sucrose response of 110 synapses from a single coverslip before and after 4α-PMA (B) or PMA (C) application. D, The average ratio of the total recycling pool in synapses after treatment to that before treatment. E, The average ratio of Δsuc/ΔF in synapses after treatment to that before treatment shows a significant increase after PMA treatment compared with 4α-PMA treatment (n = 3 and 6 coverslips for 4α-PMA and PMA, respectively, with ∼100 synapses imaged per coverslip). ^*p < 0.05. Error bars indicate SE.