Effects of levobupivacaine and bupivacaine on rat myometrium.
OBJECTIVE
To study the effect of levobupivacaine and bupivacaine on the contractility of isolated uterine muscle strips from pregnant and non-pregnant female rats.


METHODS
Full-thick myometrial strips were prepared from 18- to 21-day pregnant (n=8) and non-pregnant rats (n=7). After contractions became regular, strips were exposed to cumulative concentrations of the two drugs from 10(-8) to 10(-4) mol/L, amplitude and frequency of the uterine contraction was recorded.


RESULTS
Two local anesthetics caused a concentration dependent inhibition on contractility of myometrial strips from pregnant and non-pregnant rats. In the myometrium from non-pregnant rats, -logIC(50) of levobupivacaine and bupivacaine were 4.85 and 4.25 respectively. In the myometrium from pregnant rats, similar concentrations of levobupivacaine and bupivacaine were observed, -logIC(50) were 2.7 and 2.9 respectively. Levobupivacaine produced an increase in amplitude of contractions, while bupivacaine showed an increased trend in frequency.


CONCLUSIONS
These results demonstrate that levobupivacaine and bupivacaine may inhibit myometrium contractility. The inhibitory effect of levobupivacaine or bupivacaine is not enhanced by gestation in rat. Levobupivacaine may have more positive influence than bupivacaine in pregnant myometrium.
Li
Zi-gang
ZG
Department of Anesthesiology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
Zhou
Liang
L
Tang
Hui-fang
HF
D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002045:Bupivacaine / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D000077554:Levobupivacaine; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014590:Uterine Contraction / Q000187:drug effects*
D000779:Anesthetics, Local; D000077554:Levobupivacaine; D002045:Bupivacaine