AN EXPERIMENTAL ASPECT OF THE HYPERPOLARIZATION OF S. J. P.

In a previous paper (1) the experiments were performed from the point of view that the hyperpolarization following the S. J. P. (small-nerve junctional potential) was an essential component of an S. J. P. In fact, most of S. J. P.'s obtained were followed by the phase of hyperpolarization, but in very infrequent cases no hyperpolarization of which causes remain obscure can be observed. As its cause someone considers the effect of injury. The upper S. J. P. with a hyperpolarization in Figure 1 was obtained, in spring, from a muscle which showed a typically intensive spike potential, however, the lower S. J. P. without a hyperpolarization, in Figure 1, was, in summer, recorded from a muscle from which a relatively lower spike potential was taken. But this correlation does not be exactly. Moreover, in that paper (1) it was described that the process for the depolarization of S. J. P. and that for its hyperpolarization existed independently. This fact may be supported by the description of Stephenson (2) that potassium accumulation and membrane potential change are not significantly correlated.The present paper focuses on the process determining the hyperpolarization (always outside-positive after potential) capable of observing in the S. J. P. Because the synaptic potential such as E. P. P. decays monophasically or recovers without a positive after potential, suggesting the passive recovery of the active membrane, S. J. P. may be not a simple synaptic potential.It is probable that. S. J. P. is the synchronized activity of non-conducted responses at a few small-nerve junctions in a tonic fiber, however, if these unitary non-propaga-table responses have no positive after potential it can not be considered that S. J. P. has a following hyperpolarization.