Optical measurements of activity-dependent membrane recycling in motor nerve terminals of mammalian skeletal muscle

Proc Biol Sci. 1994 Jan 22;255(1342):61-6. doi: 10.1098/rspb.1994.0009.


Motor nerve terminals in a variety of rat and mouse skeletal muscles were stained in an activity-dependent fashion using the styryl dyes FM1-43 or FM2-10. Low-light video microscopy and digital image processing techniques were used to evaluate destaining of the preparations during application of depolarizing stimuli. Best results were obtained with the mouse triangularis sterni muscle. Quantitative analysis of the destaining of dye-loaded terminals supports the suggestion that FM1-43 stains a recycling membrane compartment, most probably synaptic vesicles. However, the pattern of staining and destaining were not the same as those reported previously for frog neuromuscular junctions. The pattern of nerve terminal staining was less punctate and the rate and amount of activity-dependent destaining were less than in frog muscle. Part of the explanation may be a more acute susceptibility of mammalian terminals to phototoxicity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Endocytosis
  • Exocytosis
  • Fluorescent Dyes
  • In Vitro Techniques
  • Mice
  • Motor Neurons / metabolism
  • Motor Neurons / ultrastructure*
  • Nerve Endings / metabolism
  • Nerve Endings / ultrastructure*
  • Pyridinium Compounds
  • Quaternary Ammonium Compounds
  • Rats
  • Synaptic Vesicles / metabolism
  • Synaptic Vesicles / ultrastructure


  • FM1 43
  • FM2 10
  • Fluorescent Dyes
  • Pyridinium Compounds
  • Quaternary Ammonium Compounds