Repetitive Activation of Motor Nerve Endings

Abstract

IT has been suggested that after repetitive activation motor nerve endings become hyperpolarized and that consequently the spike potential in the endings is larger in amplitude and more effective in transmission¹. An alternative suggestion is that activation causes a mobilization of transmitter in the terminals so that more is available for release². If the spike potential could be recorded in the terminals, it would give information about the relative importance of these two hypotheses. Hitherto this has been impossible in a mammalian preparation because there was no reliable method of locating the microscopically small endings. This difficulty can, however, be overcome by using as a criterion the ability to record extracellular miniature end-plate potentials, for it is generally accepted that this is only possible within a few micra of junctional regions³.