UTERINE POTENTIALS

¹ From the Nuffield Institute for Medical Research, Oxford

1. The action potentials of the uterus were studied under different conditions. Two different types of potential changes are found to accompany the contraction of the uterus, according to the sexual state of the organ.

2. In the non-pregnant anoestrus uterus a spontaneous contraction shows a diphasic slow wave; a contraction produced by adrenaline, pitocin, harmalol, histamine shows a monophasic slow wave, which has approximately the same duration as the contraction.

3. In late pregnancy and in oestrus these slow waves do not appear but the contraction of the uterus is accompanied by spike potentials. The number of spikes varies from 5-15 in spontaneous contractions, while in contractions caused by drugs the number depends on the dose given, the maximum observed being about 70. The average duration of a spike is 0.3-0.6 sec. and their frequency is 1-3 per sec.

4. Uteri showing progestational proliferations after injection with gonadotropic hormone show marked slow waves in spontaneous contractions, and slow waves and spikes after injection of drugs.