Mobility of synaptic vesicles in different pools in resting and stimulated frog motor nerve terminals.
We used fluorescence recovery after photobleaching (FRAP) to measure the mobility of synaptic vesicles in frog motor nerve terminals. Vesicles belonging to the recycling pool or to the reserve pool were selectively labeled with FM1-43. In resting terminals, vesicles in the reserve pool were immobile, while vesicles in the recycling pool were mobile. Nerve stimulation increased the mobility of reserve pool vesicles. Treatment with latrunculin A, which destroyed actin filaments, had no significant effect on mobility, and reducing the temperature likewise had little effect, suggesting that recycling pool vesicles move by simple diffusion. Application of okadaic acid caused vesicle mobility in both pools to increase to the same level. We could model these and others' results quantitatively by taking into account the relative numbers of mobile and immobile vesicles in each pool, and vesicle packing density, which has a large effect on mobility.
Gaffield
Michael A
MA
Neuroscience Program, University of Colorado Medical School, Aurora, Colorado 80045, USA.
Rizzoli
Silvio O
SO
Betz
William J
WJ
D000818:Animals; D066298:In Vitro Techniques; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism; D011894:Rana pipiens; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D013696:Temperature
D019319:Okadaic Acid