EDN3 and pulmonary arterial hypertension: The ET-1/ET-3 ratio, which has been reported to be a better prognostic indicator for pulmonary hypertension compared to ET-1 alone [47], was elevated in animals from the chronic exposure cohort (control and radiation-exposed animals) by comparison to the animals of the acute exposure cohort, revealing a shift of ET-1/ET-3 with progression of atherosclerosis.