Effects of magnesium and isradipine on contractile activation induced by the thromboxane A2 analog U46619 in human uteroplacental arteries in term pregnancy
| Autor: | Kristjar Skajaa, Karl-Erik Andersson, D. Svane, Axel Forman |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
medicine.medical_specialty
Digoxin Pyridines Placenta Indomethacin chemistry.chemical_element Calcium Thromboxane A2 chemistry.chemical_compound Pre-Eclampsia Pregnancy Internal medicine medicine Humans Magnesium Antihypertensive Agents Isradipine business.industry Uterus Myometrium Antagonist Dihydropyridine Obstetrics and Gynecology Arteries Calcium Channel Blockers Prostaglandin Endoperoxides Synthetic Endocrinology chemistry Female medicine.symptom business Vasoconstriction medicine.drug |
| Zdroj: | Skajaa, K, Svane, D, Andersson, K E & Forman, A 1990, ' Effects of magnesium and isradipine on contractile activation induced by the thromboxane A2 analog U46619 in human uteroplacental arteries in term pregnancy ', American Journal of Obstetrics and Gynecology, vol. 163, no. 4 Pt 1, pp. 1323-33 . Aarhus University |
| ISSN: | 0002-9378 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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