Effects of bupivacaine and calcium antagonists on human uterine arteries in pregnant and non-pregnant women.
Bupivacaine is a local anesthetic commonly used in obstetrical practice. Although not generally constrictive, it has a constricting effect on blood vessels in clinically used doses, and when administered close to the uterine vasculature, as in a paracervical blockade, it can induce severe fetal bradycardia and thus be hazardous to the fetus. The bupivacaine-induced vasoconstriction on uterine arteries from pregnant and non-pregnant women was effectively reduced by two different calcium antagonists, verapamil and nifedipine. In non-pregnant women, nifedipine (2.9 x 10(-7) mol.l-1) administered simultaneously with bupivacaine (5.8 x 10(-4) mol.l-1) caused a 96% and verapamil (10(-5) mol.l-1) an 84% reduction as compared with the control vessel where only bupivacaine (5.8 x 10(-4) mol.l-1) was administered. In pregnant women, nifedipine 2.9 x 10(-7) mol.l-1 and 2.9 x 10(-6) mol.l-1 produced 66% and 79% reductions, respectively. It is possible that calcium antagonists administered together with bupivacaine in paracervical blockade could reduce the risk of fetal bradycardia.
Norén
H
H
Department of Obstetrics and Gynecology, University of Göteborg, Sweden.
Lindblom
B
B
Källfelt
B
B
D001158:Arteries / Q000187:drug effects; D002045:Bupivacaine / Q000037:antagonists & inhibitors*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology*; D011247:Pregnancy / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil; D009543:Nifedipine; D002045:Bupivacaine