What is most likely to decrease pulmonary vascular resistance in a healthy individual?

Epoprostenol, commonly known as prostacyclin, is a potent vasodilator that specifically works on the pulmonary vasculature. It enhances blood flow through the lungs by inducing relaxation of the smooth muscle in the pulmonary arteries, which leads to a decrease in pulmonary vascular resistance. This effect is particularly beneficial in states of increased pulmonary arterial pressure or pulmonary hypertension, as it directly counteracts the vasoconstrictive effects of substances like endothelin.

In healthy individuals, the body maintains a balance of factors that regulate vascular tone. Epoprostenol acts by increasing levels of cyclic AMP within the vascular smooth muscle cells, resulting in vasodilation. This mechanism not only lowers resistance but also improves oxygenation and blood flow through the lungs.

In contrast, substances like endothelin are vasoconstrictors and would increase resistance. Conditions such as hypocapnia, which is characterized by low carbon dioxide levels in the blood, can lead to pulmonary vasoconstriction. Hypoxia, or low oxygen levels, also causes vasoconstriction in the pulmonary circulation, as a physiological response to optimize ventilation-perfusion matching.

Therefore, the unique vasodilatory properties of epoprostenol make it the most likely agent to decrease pulmonary