Rapid reuse of readily releasable pool vesicles at hippocampal synapses.
Functional presynaptic vesicles have been subdivided into readily releasable (RRP) and reserve (RP) pools. We studied recycling properties of RRP vesicles through differential retention of FM1-43 and FM2-10 and by varying the time window for FM dye uptake. Both approaches indicated that vesicles residing in the RRP underwent rapid endocytosis (tau approximately 1s), whereas newly recruited RP vesicles were recycled slowly (tau approximately 30 s). With repeated challenges (hypertonic or electrical stimuli), the ability to release neurotransmitter recovered 10-fold more rapidly than restoration of FM2-10 destaining. Finding neurotransmission in the absence of destaining implied that rapidly endocytosed RRP vesicles were capable of reuse, a process distinct from repopulation from the RP. Reuse would greatly expand the functional capabilities of a limited number of vesicles in CNS terminals, particularly during intermittent bursts of activity.
Pyle
J L
JL
Department of Molecular and Cellular Physiology, Beckman Center, Stanford University School of Medicine, California 94305, USA.
Kavalali
E T
ET
Piedras-Rentería
E S
ES
Tsien
R W
RW
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D004558:Electric Stimulation; D004705:Endocytosis / Q000502:physiology; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D006982:Hypertonic Solutions / Q000494:pharmacology; D008959:Models, Neurological; D018377:Neurotransmitter Agents / Q000378:metabolism; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism*
C073804:FM1 43; C086686:FM2 10; D005456:Fluorescent Dyes; D006982:Hypertonic Solutions; D018377:Neurotransmitter Agents; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds