INTRAVENOUS ADMINISTRATION OF COCAINE STIMULATES GRAVID BABOON MYOMETRIUM IN THE LAST 3RD OF GESTATION

OBJECTIVE: The hypothesis for this investigation was that intravenous cocaine results in a dose-dependent increase in myometrial activity of the unanesthetized, chronically instrumented gravid nonhuman primate. STUDY DESIGN: Seven chronically instrumented gravid baboons were indi vidually caged in an environment of 14 hours of light and 10 hours of darkness. Maternal femoral artery and Vein catheters and three pairs o f myometrial electromyographic wires were surgically placed at 90 to 1 21 days' gestation (term 180 days). At lesat 5 days after surgery, bol us intravenous cocaine hydrochloride doses of 0.05, 0.1, 0.3, 0.5, and 1.0 mg/kg maternal body weight were administered according to Various schedules. Myometrial activity was analyzed by quantifying the myomet rial electromyographic envelope data as the power spectral density win dow of contraction activity and as the total area under the rectified electromyographic voltage signal (i.e., total electromyographic activi ty) before and during the experimental period. RESULTS: Myometrial con traction activity increased after the 0.3 mg/kg dose (p < 0.01), the 0 .5 mg/kg dose (p < 0.005), and the 1.0 mg/kg dose (p = 0.07) compared with baseline. The total myometrial electromyographic activity also in creased as the cocaine dose increased. CONCLUSION: Intravenous cocaine results in increased myometrial contractions in the gravid baboon dur ing the latter third of pregnancy.