On a cellular level, the condition is characterised by marked endothelial dysfunction, with an excess of vasoconstrictor substances (phosphorylated myosin light chains (MLC-P), endothelin 1 (ET-1) and reactive nitrogen species) over vasodilator compounds (cGMP, cAMP, and myosin light chain phosphatase (MLCP)) [6, 7]. Here, EDN1 is linked to endothelial dysfunction.