The effects of prostaglandin E1 and prostaglandin E2 on in vitro myometrial contractility and uterine structure.

OBJECTIVE: To estimate the effects of prostaglandin E1 (PGE1) and E2 (PGE2) on myometrial contractility and structure in vitro. STUDY DESIGN: Myometrial strips from 18 women were incubated with PGE1 (10-5 mol/L), PGE2 (10-5 mol/L), or solvent (CTR) for up to 360 minutes in organ chambers for isometric tension recording. The area under the contraction curve, total collagen content, and percentage of the area covered by connective tissue were calculated at various time periods. RESULTS: PGE1 significantly increased in vitro myometrial contractility up to 90 minutes when compared with PGE2 and CTR (p < 0.01) and up to 180 minutes as compared with PGE2 (p < 0.05). After 360 minutes, CTR and PGE1 samples had lower total collagen content and area covered by connective tissue than PGE2 (p < 0.01). CONCLUSION: The effects of prostaglandins on the uterus cannot be solely explained by contractility. Treatment with PGE1 significantly increased myometrial contractions and decreased both total collagen content and the area covered by connective tissue. Such findings may explain the higher rates of vaginal delivery, tachysystole, and uterine rupture associated with PGE1 use.