Background:
Propofol is used after extraction of the fetus in pregnant women who have received combined spinal-epidural anaesthesia for caesarean section. In previous studies, it was shown that propofol has an inhibitory effect on uterine contraction like volatile anaesthesia1、2). On the other hand, it has been shown that dexmedetomidine is an α2-adrenergic agonist that induces uterine contraction via a pathway involving G protein３）. However, there are no data on a comparison of the effects of propofol, sevoflurane and dexmedetomidine on contractions of a pregnant rat myometrium in vivo. The aim of this study was to determine the effects of anaesthetic agents on contractions of the pregnant rat myometrium.
Materials and methods:
With institutional approval, pregnant rats were anaesthetized and fetuses were removed. A balloon was inserted into the uterus to measure contractions of the myometrium. Uterus muscular contractions of the pregnant rats that were sedated with propofol (30 mg/kg/hr, 150 mg/kg/hr), dexmedetomidine (6 mcg/kg/hr, 30 mcg/kg/hr) or sevoflurane (2%, 5%) were measured. Statistical analysis was performed using the unpaired t-test. P values < 0.05 were considered statistically significant.
Results:
Dexmedetomidine significantly augmented contractions of the pregnant rat myometrium. However, there were not significant difference in myometrium contractions in rats sedated with propofol or sevoflurane (figure).
Conclusions:
Dexmedetomidine may be preferable for maintaining uterine contractions in caesarean section.

REFERENCES
1) Anesthesiology 2001;95:1245-55
2) Acta Anaesthesiol Scand 2005;49:1355-1359
3) European Journal of pharmacology 2000;390:185-195

02 / Influence of anaesthetic agents on contractions of the pregnant rat myometrium in vivo.