2連Balloons留置法による無麻醉兎子宮運動の研究

第2編 無麻醉兎の子宮運動ならびに諸種子宮緊縮薬の作用と性Hormoneとの関係

抄録

Influences of sexual hormones on the uterine movement and on the effect of oxytocic agents were examined with conscious rabbits in whose uterus double balloons had been installed by the method described in the previous report (this journal 68, 1027, 1956).
The height of uterine movement curve gradually decreased in general by ovariectomy but complete ceasure of movement was rare, even one month after the operation. In some cases, decrease of wave height was not so marked, but in such rabbits, there was no cyclic change of the wave height as seen in normal rabbits.
Repeated intravenous administration of a definite amount (daily 500 i. u./kg. in 4 divided doses) of estrone in castrated does with diminished uterine movement resulted in an increased height of uterine movement curve. When the number of administration was increased, the contraction wave appeared in the form of grouping at intervals of several minutes to over 10 minutes and this grouped wave was a kind of peristaltic waves.
Progesterone (1-2mg./kg.) caused a fairly rapid decrease of wave height of uterine movement which had been increased by estrone; the movement practically stopped after a few hours.
Observations on the oxytocic effect of Atonin, Atonin-O, adrenaline, ergot preparations, quinine, Ergoklin, and sparteine in normal rabbits showed that this effect was marked when the wave height of uterine movement is large and slight when the wave height is small. In castrated rabbits, however, the effect of these drugs was slight even in case the wave height was comparatively large. On the contrary, in the rabbits under the action of estrone, the effect of all these drugs was marked dependently neither on the wave height nor on the rhythmicity.
The uterus whose movement had been weakened by progesterone showed decreased sensitivity, not only to Atonin but also to other oxytocic agents.
The uterus under the action of pitressin showed tolerance not only against pitocin but also to some other oxytocic agents. This tolerance was also observed during a certain period even after revival of uterine movement which had been stopped by pitressin.
From the foregoing findings, it may be said that there is no inevitable relationship between sensitivity of the myometrium to drugs and the state of uterine movement, and that estrone is more closely related to sensitivity of the uterus to drugs rather than to the movement of uterus.
In addition, the present series of experiments made it clear that the action of oxytocic agents does not start in any specific location in the uterus.