The ENZYME that converts angiotensin I to angiotensin II (see ANGIOTENSIN) is called angiotensin-converting enzyme. Because angiotensin II controls blood pressure whereas angiotensin I has no such activity, inhibiting the enzyme that converts angiotensin I to angiotensin II would be expected to reduce blood pressure. Consequently, ACE inhibitors have a valuable role in treating heart failure by stabilising blood pressure when thiazides and betablockers cannot be used or fail to work, especially after myocardial infarction (see HEART, DISEASES OF). Captopril was the first ACE inhibitor to be synthesised others include enalapril, lisinopril, cilazapril, quinapril and ramipril. Some kidney disorders increase the production of angiotensin II and so cause HYPERTENSION.