Home
Resources
Publications
Effects of Magnesium and Isradipine on Contractile Activation Induced by the Thromboxane A2 Analog U46619 in Human Uteroplacental Arteries in Term Pregnancy

Effects of Magnesium and Isradipine on Contractile Activation Induced by the Thromboxane A2 Analog U46619 in Human Uteroplacental Arteries in Term Pregnancy

K Skajaa, D Svane, K E Andersson, A Forman

Am J Obstet Gynecol. 1990 Oct;163(4 Pt 1):1323-33.

PMID: 2145769

Abstract:

The effects of Mg++ and the dihydropyridine calcium channel blocker isradipine on contractions induced by the thromboxane A2 mimetic U46619 were studied in isolated human uteroplacental arteries. In all preparations investigated U46619 10(-10) to 10(-6) mol/L induced concentration-related contractile responses. In maternal vessels U46619 produced a biphasic concentration-response curve, whereas the compound in fetal vessels produced a sigmoid concentration-response curve parallel to that of prostaglandin F2 alpha. Mg++ (1.0 to 6.0 mmol/L) and isradipine (10(-10) to 10(-5) mol/L) both relaxed U46619-induced contractions by up to about 40%. In preparations precontracted by U46619 and exposed to isradipine 10(-6) mol/L, addition of Mg++ 6.0 mmol/L consistently produced a further small relaxation. Removal of the endothelium or pretreatment with indomethacin 10(-6) mol/L or digoxin 10(-6) mol/L did not influence the inhibition produced by Mg++ or isradipine. In vessels pretreated in Ca(++)-free medium Mg++ 6.0 mmol/L depressed and isradipine abolished responses to Ca++ (0.01 to 4.0 mmol/L) after depolarization with K+ 124 mmol/L. In maternal and fetal arteries stimulated with U46619, however, Mg++ 6.0 mmol/L and isradipine 10(-6) mol/L produced a similar, partial inhibition of responses to Ca++ (0.01 to 4.0 mmol/L). Mg++ seems to inhibit transmembrane Ca++ influx, although less efficiently than the dihydropyridine calcium antagonist isradipine. In addition, Mg++ may interfere with Ca++ at intracellular binding sites. Provided that preeclampsia comprises enhanced vascular actions of thromboxane A2, the present results support the established use of Mg++ in the treatment of this condition and suggest that calcium antagonists are of potential benefit.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP116169187	Isradipine Related Compound A		116169-18-7	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: