Cushioning the Flow

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Science  10 Nov 2006:
Vol. 314, Issue 5801, pp. 895
DOI: 10.1126/science.314.5801.895a

The ductus arteriosus (DA) is a vessel that connects the pulmonary artery and aorta in a developing fetus; blood bypasses the immature fetal lungs and flows to the placenta, where the carbon dioxide is exchanged for oxygen. Shortly after birth, when the neonatal lungs take over responsibility for oxygenation of the blood, there is no longer any need for the DA, and, normally, it closes. However, in about 1 in 2000 infants, and more frequently in those born prematurely, the DA fails to close. This condition, called patent DA (PDA), can strain the lungs and lead to various forms of vascular disease.

The DA remains open in the fetus in part through the vasodilatory effects of circulating prostaglandins such as PGE, and for this reason drugs (such as indomethicin) that inhibit the production of PGE by cyclooxygenase (COX) are commonly used to treat PDA. Working in a rat model system, Yokoyama et al. discover that the role of PGE in this setting may be more complex than previously thought. They find that PGE prepares the fetal DA for closure by promoting the formation of the “intimal cushion,” a buildup of smooth muscle cells and extracellular matrix that anatomically occludes the vessel. If PGE is found to have the same opposing effects on DA patency in humans, then this discovery could lead to better treatments for PDA. — PAK

J. Clin. Invest. 116, 3026 (2006).

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