Magnesium sulfate - induced relaxation of uterine arteries from pregnant and nonpregnant patients

Article Abstract:

Magnesium sulfate, administered into the circulation, is used as a supplement in treating hypertension (high blood pressure) associated with pregnancy. In animal studies, magnesium sulfate was shown to increase blood flow to the uterus and placenta by reducing the resistance to flow in the arteries of the uterus. Arterial resistance in pregnant women may result from the loss of the smooth muscle layer in the arteries during early pregnancy. Magnesium sulfate may dilate (relax) blood vessels by competitively preventing the action of calcium to cause muscle contraction, or by contributing to the release of factors that cause vasodilation. The effect of pregnancy on the ability of magnesium sulfate to dilate uterine arteries was assessed. In addition, the mechanism by which magnesium sulfate dilates blood vessels, either by counteracting calcium or by releasing vasodilators, was examined. The effects of various doses of magnesium sulfate on segments of uterine arteries from pregnant and nonpregnant patients were evaluated. Magnesium sulfate resulted in relaxation of uterine artery contractions caused by norepinephrine and potassium chloride. The effects of magnesium sulfate were greater in uterine arteries from pregnant women than in those from nonpregnant women. A larger dose of magnesium sulfate was required to cause the same degree of uterine artery relaxation in nonpregnant women. Magnesium effects were prevented by the addition of calcium chloride; this is consistent with the theory in which magnesium sulfate causes vasodilation by competing with calcium. In addition, the effects of magnesium sulfate were not prevented by agents or actions that remove vasodilators, suggesting that magnesium sulfate does not act by releasing vasodilators. These findings show that magnesium sulfate is a powerful vasodilator of the uterine artery, particularly in pregnant women, and may help to improve blood flow to the uterus. (Consumer Summary produced by Reliance Medical Information, Inc.)

Blood vessels, Magnesium sulfate

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Possible physiologic role of calcitonin gene-related peptide in the human uterine artery

Article Abstract:

The effectiveness of calcitonin gene-related peptide (CGRP) may increase during pregnancy. CGRP may increase dilation of the blood vessels of the uterus, especially in pregnant women. Among 28 women who underwent a hysterectomy, nine were pregnant and 19 were not. Treatment with CGRP relaxed norepinephrine-induced contractions in the uterine arteries from both pregnant and non-pregnant women. Relaxation of the uterine arteries increased as the concentration of CGRP increased, and the effect was larger in pregnant women than in non-pregnant women. The concentration of CGRP was almost 10 times higher in the uterine arteries from pregnant women than in those from non-pregnant women. The blood vessels of the uterus play an important role in supplying different types of nutrients to the fetus during pregnancy.

Peptide hormones, Pregnancy

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Maternal corticosteroids to prevent intrauterine exposure to hyperthermia and inflammation: A randomized, double-blind, placebo-controlled trial

Article Abstract:

A 2-phase, randomized, double-blind, placebo-controlled trial is performed to determine whether prophylactic maternal corticosteroid treatment prevents fetal exposure to hyperthermia and inflammatory cytokines after epidural analgesia. It is observed that prophylaxis with high-dose corticosteroids significantly reduces fetal exposure to hyperthermia and inflammation, but maternal high-dose corticosteroids increase the rate of neonatal asymptomatic bacteremia.

United States, Prevention, Complications and side effects, Corticosteroids, Inflammation, Fever, Hyperthermia, Prenatal influences, Corticosteroid drugs, Clinical report

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