Differential regulation of myometrial prostaglandin production by changes in length

Objective The purpose of this study was to determine whether stretching and shortening of human myometrial strips alters prostaglandin production. Study Design We measured 6-keto prostaglandin F 1α (PGF 1α ; a PGI 2 metabolite) and PGF 2α in the contraction baths of myometrial strips that were obtained at cesarean delivery from 5 term pregnant women. Fluid was collected after the stretching and after the strip lengths were decreased by 4%, 6%, or 8%. Prostaglandin concentrations were measured in triplicate by competitive enzyme immunoassay and compared by Kruskal–Wallis tests. Results Stretching myometrial strips increased the production of 6-keto PGF 1α by 31%, but not PGF 2α . Shortening strips had little effect on 6-keto PGF 1α production, but increased PGF 2α production by 158%. Conclusion Stretching myometrial strips from pregnant women increases synthesis of PGI 2 ; shortening strips increases synthesis of PGF 2α . Differential prostaglandin synthesis that is related to myometrial stretching and shortening could play a role in uterine quiescence during gestation and increased contractility during parturition.