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Effect of Dexmedetomidine on Isolated Human Myometrial Contractility: An in-vitro Study
Abstract Number: O2-03
Abstract Type: Original Research
Dexmedetomidine, a selective alpha-2 agonist, has been used extensively in anesthesia during the recent years. Its application in labor analgesia has been reported. However, there is concern regarding its increased contractility effect on human myometrium.
Following approval by the institutional ethics committee, 6 healthy term parturients scheduled for elective caesarean delivery were recruited. All parturients had a lower segment transverse incision which was performed under spinal anesthesia. After the delivery of fetus and placenta, longitudinal section of myometrial tissue was excised from the midline portion of the lower uterine incision. Oxytocin infusion was withheld until the sample myometrium was collected. The myometrial tissue was then placed in Krebs buffer, mounted in the myograph. Normal saline and five incremental concentration of doses of dexmedetomidine, at 0.1 ng/mL, 1 ng/mL, 10 ng/mL, 100 ng/mL, and 1 mcg/mL, were sequentially microinjected into the bath. The myometrial contractile characteristics after each drug injection, including contractile force, interval and duration, were analyzed.
Dexmedetomidine demonstrated no significant effect on the spontaneous contractile characteristics of human myometrial strips in all concentrations listed above. Positive control group was added with exposing human myometrial strips in 0.01 U/mL oxytocin, which revealed increased contractile frequency and force. Addition of dexmedetomidine did not provide enhancement of myometrial contractility.
In our study, dexmedetomidine did not reproduce the in-vitro contractile-enhancing effects on human myometrium which was demonstrated by Sia, et al. An recent investigation of dexmedetomidine effect on rat uterine muscle revealed reduced contractile frequency in Krebs solution and decreased contractile force in Ca2+-free solution during late-pregnancy, suggesting that this phenomenon could be related to stage of pregnancy and intracellular Ca2+ level. We are currently investigating the issue.
1. Zhou, et al. SOAP 2011
2. Sia, et al. Int J Obstet Anesth 2005
3. Ocal, et al. Indian J Pharmacol 2013