MMP2/9 inhibition reduces oxytocin-induced contraction in myometrial tissue from pregnant women, while addition of purified MMP2/9 enhances contraction. (A) Freshly isolated term nonlaboring myometrium was dissected, and uterine strips were tested for the ability to contract in response to 60 mM KCl. Tissues were then stimulated with 8 nM oxytocin (OT), and baseline contractions were recorded. Increasing concentrations of SB-3CT were added, followed by washout (W), and tissue was re-stimulated with 8 nM OT. (B) Vehicle or 1 μM SB-3CT was added to tissue baths and contractile responses were compared (n = 7 patients in duplicate or triplicate); SB-3CT reduced mean contractile force by 34%. (C) Purified MMP2/9 (17 and 13 nM, respectively) or vehicle control was added to tissue baths, and changes in the contraction profiles were recorded (n = 3 patients in duplicate); MMP2/9 increased mean contractile force by 36%. Data in B and C are presented as the percent change in the area under the curve over time, *P < 0.05. Scatter dot plots show mean +/– standard deviation.