Effect of indomethacin on stretch-induced uterine activity in the post-partum.

The uterus at 48 hours after normal delivery was mechanically stretched by the intra-uterine application of an inflated rubber balloon. Inauguration of regular and marked uterine activity was noted subjectively in all 16 healthy subjects and recorded by an external tocometer. The inaugurated uterine activity was significantly suppressed by the rectal application of 100 mg of indomethacin (p less than 0.01), but was not abolished entirely. The uterine activity ceased gradually with the discontinuation of stretching. These results strongly indicate that the purely stretch-induced uterine contractions are mediated by prostaglandins (PGs) which are released by stretching and/or thereby induced uterine contractions. In this study the possible source of PGs appeared to be by the myometrium itself.