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The potent stimulant of smooth muscle contraction that is essential for ductus arteriosus closure is increased due to?
Circulating prostaglandins
Oxygen tension
Pulmonary vascular resistance
Carbon dioxide levels
The correct answer is: Oxygen tension
Oxygen tension plays a crucial role in stimulating the contraction of smooth muscle, particularly in the context of the ductus arteriosus. After birth, there is a significant increase in arterial oxygen levels as the newborn begins to breathe air. This increase in oxygen tension leads to the release of signaling molecules that promote vasoconstriction, which is vital for the closure of the ductus arteriosus. The closure of this structure is a normal physiological process that occurs shortly after birth, transitioning circulation to the postnatal pattern. The other options, such as circulating prostaglandins, typically maintain the patency of the ductus arteriosus during fetal life, while increased pulmonary vascular resistance is more related to the changes in blood flow after birth. Carbon dioxide levels, although important in various physiological processes, are not primarily responsible for the direct stimulation of ductal closure. Thus, oxygen tension is essential for promoting the necessary smooth muscle contraction and facilitating the normal transition from fetal to postnatal circulation.