The effects of posterior pituitary hormones on isometric tension and isotonic shortening of the pig myometrium

Abstract

Abstract Isotonic recording showed that uteri in the luteal stage of the oestrus cycle were more sensitive to oxytocin and vasopressin than those in the follicular stage. The uterine horn was more sensitive than the cervix. A comparison of isotonic and isometric recording revealed that the former exaggerated the response to oxytocin. Under isometric conditions there was no difference in sensitivity to oxytocin between progesterone-dominated and oestrogen-dominated uteri, but both were more sensitive than immature uteri. Tension developed in response to oxytocin was greatest in oestrogen-dominated, less in progesterone-dominated and least in immature uteri.