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 h uman myometrium.STUDY DESIGN: Myometrial samples were obtained from th e lower uterine segment at elective cesarean section from five women a t term who were not in labor and who had no perinatal risk factors. My ometrial strips were suspended in contractile buffer, and isometric co ntractions were measured. Frequency, amplitude, duration, and integrat ed area (mean +/- SE) were compared before and after the addition of c ocaine (10(-6) to 10(-4) mol/L) by means of analysis of variance and D uncan'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). Integ rated 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) m ol/L, 3.5 +/- 0.23, p < 0.001). These effects were dose dependent. CON CLUSION: Cocaine acutely increases contractile activity in myometrium isolated from pregnant women.