The effect of the pituitary on the isolated human uterus. (Preliminary communication.)

Kehrer claims that an extract of the posterior lobe of the pituitary gland is the ideal ecbolic. Indeed, he goes so far as to suggest that the secretion of this portion of the gland is the hormone which induces labor.

In studying the effects of pituitary extracts on isolated human Fallopian tubes and uteri my attention was arrested by the difference in the response of the non-pregnant and parturient organs. The contractions of the parturient tube and uterus were invariably increased in rate and strength when extracts of the gland were applied. The same stimulation was found when an ectopic tube was studied.

The effect of pituitary on the non-pregnant tube or uterus is wholly different. Small doses usually have no effect. Large doses, such as produce marked stimulation of the pregnant uterus, may cause a very definite depression or they may not influence the movements at all. To what is this change in the response of the non-pregnant and parturient uterus due? The simplest explanation would be that, like the cat's uterus, the human organ changes its innervation, or, rather, during pregnancy its motor innervation becomes predominant. Such, however, is not the case, for epinephrine produces stimulation of the human uterus whether it is pregnant or not. Furthermore, the parturient uterus does not appear to be more susceptible to epinephrine. The only explanation which offers itself is that some substance sensitizes the uterus to pituitary. What this substance is, whether fetal or maternal in origin, I have not yet been able to determine. The sensitizer is certainly not epinephrine, because the previous application of this sympathonimetic amine does not influence in any way the reaction of the non-pregnant organ to pituitary.