The site of origin of Biedermann fibrillary twitchings under various conditions.

Abstract

1. On the toad's limb muscles such as sartorius, iliofibularis, gracilis, glutaeus magnus, adductor magnus and gastrocnemius, the motor end-plate zone was determined by means of analysing action potentials led by a septal method. For stimulation of the nerve, isotonic citrate solution was applied to the desheathed nerve or injected into the nerve trunk.2. In these muscles a great majority of end-plates generating propagated muscle impulses was concentrated to one or two zones within a few mm. from its nerve entry.3. The site of origin of BFT impulses was also investigated by the similar means. In ordinary condition, the site situated at a band rather distant away from the end-plate zone.4. The site of origin was shifted from the original site and approached towards the end-plate zone by raising or lowering of fluid temperature from optimum which varied according to the seasons.5. Also shift of pH from the optimum, about 7, got the site of origin approach the end-plate zone.6. On decreasing the saline concentration, the osmotic pressure being compensated by adding glucose solution, the site of origin was shifted towards the end-plat zone with decreasing of saline concentration.7. These environments inadequate for the fibrillating muscle made the site of origin shift towards the end-plate zone, finally getting to the latter.8. The shift of the site of origin of BFT, the relation between its site and the end-plate and distribution of motor end-plates were discussed.