<prompt> Which of the following causes vasodilation in the pulmonary circulation?HypercarbiaHypoxiaPGEPGI  <response>: Substances producing pulmonary vasodilation include nitric oxide, prostacyclins, a2 and b2 adrenergic stimulation, histamine etc. Hypercapnia, hypoxy endothelin I, a1 adrenergic, angiotensin II, thromboxane produce pulmonary vasoconstriction. 