Korean J Anesthesiol.  2002 Jun;42(6):766-775. 10.4097/kjae.2002.42.6.766.

Effects of Bupivacaine and Magnesium on Serotonin-induced Vasocontraction in an Isolated Human Umbilical Artery

• Lee HW
• Son SC

• KMID: 2031994
• DOI: http://doi.org/10.4097/kjae.2002.42.6.766

Abstract

BACKGROUND: Serotonin is found in the blood of the umbilical cord at birth in concentrations sufficiently high to affect vascular tone. Serotonin has been suggested to be involved in the pathogenesis of preeclampsia. Magnesium sulfate (MgSO4) is used to treat convulsions and hypertension in patients with preeclamptic toxemia. Bupivacaine is used in the epidural anesthesia for a cesarean section. The effects of magnesium and bupivacaine on serotonin-induced vasocontraction in a human umbilical artery was investigated.
METHODS
Experiments were performed on 52 human umbilical arteries. The rings were suspended in an organ bath to record isometric mechanical activity. The concentration-contraction responses to bupivacaine, magnesium and serotonin were measured respectively. Vessels were pretreated with bupivacaine (10(-5) M) or magnesium (2 mM or 6 mM), and then serotonin (10(-9) M - 10(-6) M) was added cumulatively. Data analysis was assessed by an unpaired t test, one-way ANOVA and a Kruskal-Wallis test.
RESULTS
Bupivacaine induced a contraction of umbilical arterial rings, and showed a maximal contraction (51.8 +/- 6.1%) at a concentration of 43nM. Magnesium induced relaxation of the umbilical artery in a concentration dependent manner. Pretreatment with bupivacaine (10(-5) M) potentiated significantly the concentration response to serotonin (P < 0.05). Pretreatment with MgSO4 (2 mM or 6 mM) significantly suppressed the contractile response to serotonin (P < 0.05).
CONCLUSIONS
Bupivacaine, magnesium and serotonin are vasoactive on human umbilical arteries. Magnesium exerts a strong relaxant effect on serotonin induced vasocontraction in the human umbilical artery. Potentiation of serotonin induced vasoconstriction by bupivacaine may play a significant role in the reduction of umbilicoplacental blood flow.

Keyword

Buivacaine; human umbilical artery; magnesium; serotonin; vasoconstriction

MeSH Terms

Anesthesia, Epidural
Baths
Bupivacaine*
Cesarean Section
Female
Humans*
Hypertension
Magnesium Sulfate
Magnesium*
Parturition
Pre-Eclampsia
Pregnancy
Relaxation
Seizures
Serotonin
Statistics as Topic
Toxemia
Umbilical Arteries*
Umbilical Cord
Vasoconstriction
Bupivacaine
Magnesium
Magnesium Sulfate
Serotonin