THE ACUTE EFFECT OF COCAINE EXPOSURE ON PREGNANT HUMAN MYOMETRIAL CONTRACTILE ACTIVITY

OBJECTIVE: The objective of this study was to test the hypothesis that cocaine acutely increases contractile activity in isolated pregnant human myometrium. STUDY DESIGN: Myometrial samples were obtained from the lower uterine segment at elective cesarean section from five women at term who were not in labor and who had no perinatal risk factors. Myometrial strips were suspended in contractile buffer, and isometric contractions were measured. Frequency, amplitude, duration, and integrated area (mean +/- SE) were compared before and after the addition of cocaine (10(-6) to 10(-4) mol/L) by means of analysis of variance and Duncan's multiple range test. RESULTS: Contraction duration, expressed relative to control, increased acutely after addition of cocaine (10(-5) mol/L, 2.0 +/- 0.29; 10(-4) mol/L, 2.8 +/- 0.64) (p < 0.001). Integrated area of contractions also increased relative to control (10(-6) mol/L, 1.6 +/- 0.18, p < 0.05, 10(-5) mol/L, 2.4 +/- 0.16 and 10(-4) mol/L, 3.5 +/- 0.23, p < 0.001). These effects were dose dependent. CONCLUSION: Cocaine acutely increases contractile activity in myometrium isolated from pregnant women.