EDN1 and Hypertension: However, no correlation could be found between matrix metalloproteinase (MMP)-1, the tissue inhibitor of MMP-1 (TIMMP-1), PWV and blood pressure in patients who received perindopril for six months.15 A more recent study showed that ET-1 contributed to a decreased arterial compliance in hypertension through inhibition of collagen degradation.13 Furthermore, it has been shown that captopril therapy in congestive heart failure decreased endothelin production.12