STUDIES ON THE ACTION POTENTIAL OF URINARY BLADDER

Abstract

Bladder potentials were recorded in the resting and stimulating time of the pelvic nerve, using the exposed urinary bladder and pelvic nerve of guinea pig. The correlation between tonic impulses and the mechanism of urination was investigated as follows.
1) The tonic impulses of the urinary bladder are composed of small sized potentials with 7-8impulses/sec and large ones with 1-2impulses/sec.
2) Bladder potentials are consisted of many group potentials arising from each bladder muscle fiber. They do not conduct all over the urinary bladder.
3) The wave of the tonic impulses of the pelvic nerve corresponds to that of the urinary bladder, though both are not the same. The bladder tonic potential is considered to be the compound potential with automatic rhythmic discharges of the urinary bladder and those of the pelvic nerve.
4) The stimulation of pelvic nerve induces the compound bladder potentials repetitively. This repetition of the bladder potential is brought about as the after-discharges of the pelvic nerve, which is considered as the mechanism to maintain the tonus of the bladder.
5) The repetitive stimulation of the pelvic nerve accelerates its after-potential and shortens its interval. However, it was clarified that after-potentials were inhibited by the repetitive stimulations for a long period of time.
6) The bladder potential is inhibited up to a certain limit by the elongation of the urinary bladder, thereafter a predominant bladder potential and the urination occurs. This fact is considered to be the mechanism of the urination reflex.
7) A marked bladder potential with series of downward spikes occurs during urination. Therefore, the bladder contraction passes from the apex to the neck of the bladder. Furthermore, the predominant bladder potentials are maintained for several seconds even after urination.