The Effects of Ketamine on Rat Myometrial Contractility

An, Tae Hun; So, Keum Young

Abstract

BACKGROUND
It has been reported that ketamine induced contraction of the uterus. Therefore, it has been recommended as a suitable obstetric anesthetic agent. However, some investigators reported that ketamine inhibited contraction of rat uterine smooth muscle. There has been argument about its effect on the uterine contraction. The aim of the present study was to investigate the effect of ketamine on rat uterine contractile activity in vitro.
METHODS
Uterine smooth muscle tissues were obtained from non-pregnant rats (n = 20). The uterine ring segments were mounted in organ bath filled with Krebs solution with 95% O2 and 5% CO2. After spontaneous activity had been accomplished, ketamine in various concentrations (10(-7) M to 10(-3) M) was added cumulatively to the bath and the effects were continuously registered.
RESULTS
Ketamine in dose of 10(-5) M increased spontaneous myometrial contractile activity. But, ketamine in doses of 10(-4) to 10(-3) M induced a dose-dependent inhibition of spontaneous myometrial contractile activity.
CONCLUSIONS
Ketamine constricted the uterine smooth muscle in concentration of 10(-5) M but, relaxed the uterine smooth muscle in high concentrations (10(-4) to 10(-3) M).