STUDIES ON THE ACTION CURRENT IN THE UTERUS LED BY NEEDLE OR CO-AXIAL EIECTRODES

Abstract

1. Action potentials were led from the uterine muscle by the needle electrodes or by the co-axial electrodes.
2. The wave forms of action potentials which are supposed to be led from several excitable units, are diphasic or triphasic.
3. The longest duration of spontaneous action potential is about 300 msec., andd that which evoked by stimulation is 300-400 msec.
4. The duration of action potential is affected by the distance of both electrodes. Stronger stimulation evokes stronger action potential and the duration of it also increases. And, when the stimulus reaches some definite strength, the duration and strength of the action potential show their maximal values, and notwithstanding further strengthening of the stimulus, it maintains these values. The conduction velocity of the impulse in the uterine muscle is 1.83 cm/sec at 26°C.
5. From the above mentioned results, the authors concluded that the “all or none” law is valid for the excitable unit of uterine muscle.