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. Author manuscript; available in PMC: 2013 Mar 1.
Published in final edited form as: Clin Perinatol. 2012 Mar;39(1):149–164. doi: 10.1016/j.clp.2011.12.006

Fig. 2.

Fig. 2

Endothelin (ET)-1 signaling pathway in the regulation of pulmonary vascular tone. Big ET-1 is cleaved to ET-1 by endothelin converting enzyme (ECE) in endothelial cells. ET-1 binds its specific receptors ETA and ETB with differential effects. Binding of ET-1 to ETA or ETB on smooth muscle cells leads to vasoconstrictive and proliferative effects. ETB are transiently expressed on endothelial cells after birth; binding of ET-1 to ETB on endothelial cells leads to downregulation of ECE activity and increased production of nitric oxide (NO) and prostacyclin (PGI2), which led to vasodilation and antiproliferation.