Effects of vasodilators on isolated human uteroplacental arteries

Article Abstract:

Pregnancy may be complicated by hypertension (abnormally high blood pressure) which is characterized by increased resistance to blood flow and reduced blood flow within the placenta, the tissue from which the fetus derives its nutrition. The objective of treatment is to maintain adequate blood flow to the placenta. The effects of vasodilators, or pharmaceutical agents that relax blood vessels, on the mother and on the fetus within the placenta and uterus vary depending on the drug. Hydralazine is commonly used to treat pregnancy-related hypertension and relaxes the smooth muscle of the blood vessels. Blood pressure in pregnant hypertensive patients can also be reduced by combined treatment with alpha- and beta-receptor antagonists, such as prazosin and labetalol, respectively. Calcium channel blockers such as dihydropyridine and nitrendipine cause blood vessel dilation by preventing contraction of the blood vessels. The effects of hydralazine, prazosin, labetalol, and nitrendipine on contraction of maternal and fetal blood vessels caused by potassium, noradrenaline, vasopressin, angiotensin II, and prostaglandin F2-alpha (PGF2-alpha) were assessed. Hydralazine had no effect on contraction caused by various factors in maternal and fetal blood vessels. Labetalol and prazosin only reduced noradrenaline-induced contraction of maternal blood vessels, but labetalol, prazosin, and noradrenaline had no effect on fetal blood vessels. Nitrendipine prevented contraction of maternal blood vessels induced by all factors. This drug also prevented contraction caused by potassium and PGF2-alpha but not angiotensin II-induced contraction of fetal blood vessels. These findings show that the effects of different types of vasodilators vary in fetal and maternal blood vessels and depend on the factor that stimulates blood vessel contraction. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Drug therapy, Pregnancy, Complications of, Pregnancy complications, Vasodilators, Vasodilator agents, Hypertension in pregnancy, Gestational hypertension, Vasoconstrictors, Vasoconstrictor agents

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Changes in amino acids, ammonium, and coagulation factors after transcervical resection of the endometrium with a glycine solution used for uterine irrigation

Article Abstract:

The practice of irrigating the uterus with 1.5% glycine during transcervical resection for abnormal bleeding appears to cause toxic reactions due to absorption of glycine and large amounts of fluid. During transcervical resection, a solution of 1.5% glycine, an amino acid, is infused under pressure to distend the uterus, and the uterine lining and any fibroid tumors are removed. Blood samples were taken periodically before and after surgery from 101 women. Samples were analyzed for glycine, and other amino acids because glycine converts to other amino acids within the body, as well as sodium, ammonium, and coagulation factors. All women showed elevations of glycine and other amino acids and reductions in sodium. About one-third of women experienced nausea after surgery, a toxic symptom. Nauseous patients had significantly greater excursions from normal levels. Elevated levels of amino acids can produce toxic effects as can abnormally low sodium levels. Reduced sodium levels are caused by absorption of large amounts of low-sodium fluid.

Causes of, Surgery, Nausea, Endometrium, Amino acids

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The effect of oophorectomy on mechanical properties of rabbit cerebral and coronary isolated small arteries

Article Abstract:

Removal of the ovaries and cessation of ovarian hormones may increase blood flow resistance in brain arteries but not in heart arteries. Researchers removed the ovaries of rabbits, waited six weeks for the ovarian hormones to be extinguished, and then examined the small brain and small heart arteries for responses to constricting and relaxing agents. Blood flow force increased in small brain arteries in response to constricting drugs. These results may explain why blood vessels in the brains of postmenopausal women show resistance in Doppler ultrasound examinations.

Arteries, Ovariectomy

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