EDN1 and Hypertension: They had significantly higher levels of serum ET-1 (6.05 ± 1.91 vs. 4.13 ± 1.89, p = 0.013) and lower levels of serum NO (20.97 ± 4.54 vs. 27.6 ± 10.14, p = 0.008) than patients without hypertension.