Angiotensin-converting enzyme activity and contractile effects of angiotensin I and II in human uteroplacental arteries

Article Abstract:

Angiotensin-converting enzyme activity appears to increase markedly within arteries within the uterine muscle of term pregnant women compared with nonpregnant women, but fetal arteries within the placenta show much less activity. The angiotensins are a family of substances that cause blood vessel constriction. Small samples of uterine muscle were obtained from the edge of the incision among healthy women having an elective cesarean section, nonpregnant women having a hysterectomy, and from the placentas of infants after term vaginal births. Arteries were dissected out and rings were suspended in culture medium. Contractility of the tissue was measured by angiotensin stimulation and radioimmunoassays were performed for angiotensin converting enzyme. Tissue was also examined microscopically. Physical observation showed no differences, Contractile studies found different responses in the groups according to angiotensin concentration. ACS activity was highest in the pregnant women's tissue than the other two groups.

Angiotensin converting enzyme, Umbilical arteries

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Endothelin-1: immunocytochemistry, localization of binding sites, and contractile effects in human uteroplacental smooth muscle

Article Abstract:

The protein endothelin-1 may play a role in regulating uteroplacental blood flow and muscular contractions. Tissue samples were taken from human umbilical cords, human placentas and human uteri from pregnant and non-pregnant women and mixed with radioactively labelled endothelin-1. No specific antibody complexes with the labelled endothelin-1 were observed. In the placentas, binding sites for endothelin-1 were especially dense in the chorionic villi and blood vessels of the smooth muscle. Few binding sites were found in the Wharton's jelly of the umbilical cord. In the uteri from pregnant women, binding sites were especially prevalent in the smooth muscle and the blood vessels of the smooth muscle. Few were seen in the connective tissues of the uterus. Application of endothelin-1 to uterine muscle tissues and blood vessels induced significant contractions in both.

Endothelin, Myometrium

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Calcium channel blockade (isradipine) in treatment of hypertension in pregnancy: a randomized placebo-controlled study

Article Abstract:

Pregnant women with high blood pressure but not protein in the urine may be helped by treatment with the calcium channel blocker isradipine. Researchers compared the effect of isradipine to placebo in 111 pregnant women with hypertension. Isradipine significantly lowered blood pressure in most of the women. It initially lowered blood pressure in women with hypertension and protein in the urine, but the effect of the treatment wore off after about a week. Isradipine did not diminish blood flow in the umbilical artery, and it did not cause major adverse effects in the mothers. It may be safely used to treat hypertension in the third trimester of pregnancy.

Evaluation, Drug therapy, Preeclampsia, Calcium channel blockers

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