The plantar nerves-lumbrical muscles: a useful nerve-muscle preparation for assaying the effects of botulinum neurotoxin.

The plantar nerves-lumbrical muscles (PL) of the hindpaw of the mouse is a preparation that is particularly useful for assaying the effects of botulinum neurotoxin (NT) on the mammalian neuromuscular junction. Each mouse provides a minimum of 4 and a maximum of 8 such preparations. The muscles are thin enough so that neuromuscular junctions can be easily located with Nomarski interference contrast optics for impaling with microelectrodes. The preparations are small enough so they can be sectioned transversely or longitudinally, in their entirety, for light and electron microscopy, or just the regions containing end-plates can be used. An examination of the responses of this preparation to types A and E NT reveal its exceptional suitability for experiments with NT. The small number of fibers and their arrangement permit assays of low concentrations of NT to proceed to complete and total paralysis in a convenient period of time.