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

Rationale:

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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