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      Monitoring Synaptic Function at the Neuromuscular Junction of a Mouse Expressing SynaptopHluorin

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          Abstract

          We monitored presynaptic exocytosis and vesicle recycling at neuromuscular junctions of transgenic mice expressing synaptopHluorin (spH), using simultaneous optical and electrophysiological recordings. Synaptic transmission was indistinguishable from that in wild-type controls. Fluorescence rose during and decayed monotonically after stimulus trains to the nerve, with amplitudes and decay times increasing with the amount of stimulation. The relatively large size of synaptic terminals allowed us to examine the spatial profile of fluorescence changes. We identified hot spots of exocytosis, which were stable with repeated trains. Photobleach experiments showed that spH freshly exposed by nerve stimulation was not preferentially retrieved by compensatory endocytosis; instead, most retrieved spH preexisted in the surface membrane. Finally, we compared fluorescence and electrical [summed end-plate potentials (EPPs)] estimates of exocytosis, which diverged during repeated trains, as fluorescence exceeded summed EPPs, although the average amplitude of miniature EPPs was unchanged. This might reflect exocytosis of spH-containing, acetylcholine-free (“empty”) vesicles or other organelles during intense stimulation.

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          Author and article information

          Journal
          J Neurosci
          J. Neurosci
          jneuro
          jneurosci
          J. Neurosci
          The Journal of Neuroscience
          Society for Neuroscience
          0270-6474
          1529-2401
          16 May 2007
          : 27
          : 20
          : 5422-5430
          Affiliations
          [1] 1Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain, and
          [2] 2Department of Physiology and Biophysics and
          [3] 3Neuroscience Program, University of Colorado Medical School, Aurora, Colorado 80045
          Author notes
          Correspondence should be addressed to Lucia Tabares, Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avenida Sanchez Pizjuan 4, 41009 Seville, Spain. ltabares@ 123456us.es
          Article
          PMC6672353 PMC6672353 6672353 3223407
          10.1523/JNEUROSCI.0670-07.2007
          6672353
          17507564
          59a1f3ac-81bc-486b-be9a-9ac93bcbf9b2
          Copyright © 2007 Society for Neuroscience 0270-6474/07/275422-09$15.00/0
          History
          : 14 February 2007
          : 13 April 2007
          : 18 April 2007
          Categories
          Articles
          Cellular/Molecular

          vesicle recycling,synapse,neuromuscular,FRAP,synaptic vesicle,pHluorin

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