The Correct Answer is B!

The pulmonary circulation has a number of vasoactive pathways, which control the balance between vasoconstriction and vasodilatation, as well as affect proliferation and anti-proliferation. Which of the following is a prominent pathway in vasoconstriction?

A. Phosphodiesterase inhibition
B. Increase in ET1
C. Increased production of PGI2
D. Increase in eNOS pathway


Three pathways affect pulmonary vasoactivity as well as vessel proliferation: the prostacyclin, the nitric oxide, and the endothelin pathways. An increase in ET1 is a potent vasoconstrictor with high levels found in patients with PH. PGI2 and eNOS are vasodilators, and phosphodiesterase inhibition provides more cGMP through the nitric oxide pathway.

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