In vitro Study of the Effect of Clonidine on Human Umbilical Artery Motility
作者:
L.C. França,
S.P. Cunha,
R.M.F. Castro,
N.Y. Nagata,
期刊:
Gynecologic and Obstetric Investigation
(Karger Available online 1994)
卷期:
Volume 38,
issue 1
页码: 18-20
ISSN:0378-7346
年代: 1994
DOI:10.1159/000292437
出版商: S. Karger AG
关键词: Clonidine;Human umbilical artery;α-Methyldopa;α-Adrenergic receptors;Yohimbine
数据来源: Karger
摘要:
The umbilical-placental circulation is of vital importance for fetal survival and has a dominant effect on the cardiorespiratory physiology of the fetus. The mechanisms of regulation of umbilical vessels appear to differ from those regulating other vessels. Both clonidine and α-methyldopa have been used in the management of hypertensive complications of pregnancy. In contrast to α-methyldopa, clonidine does not require previous metabolization but acts directly on the receptors. The action of the two drugs on human umbilical artery was studied in vitro. Forty-eight human umbilical artery segments were dissected and perfused as follows: 9 segments with α-methyldopa, 10 with clonidine, 10 with yohimbine, 9 with α-methyldopa in combination with yohimbine, and 10 with pure Tyrode’s solution. α-Methyldopa had a statistically significant vasoconstrictive effect starting at 40 min (p < 0.05) and this effect was blocked by yohimbine (p < 0.05). Clonidine had no vasoconstrictive effect. The present data for clonidine do not confirm the presence of α2-adrenergic receptors in the umbilicoplacental circulation which had been indicated by the action of methyldopa.
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