Collagenase activity in the human cervix uteri after prostaglandin E2 application during the first trimester

Cervix biopsies were obtained during the first trimester from plurigravidae and primigravidae at various times after intracervical application of prostaglandin E2. The tissues were extracted with Ca(2+)-containing buffer, and collagenase activity was determined in these extracts using a solid phase assay in which triple helical 125I-labelled collagen was cleaved. Collagenase was detected in all samples but elevated activity was present only during a short temporal window after prostaglandin application. Maximal activity was observed 1 and 2 h after application of prostaglandin in multigravidae and 4 h in primigravidae. These data can explain why collagenase activity in cervical tissues after prostaglandin application had previously not been found. They indicate somewhat different mechanisms of cervical ripening in primigravide compared to multigravidae.