Angiotensin-converting enzyme: Induction by hypertension-induced vessel distension

Vascular angiotensin-converting enzyme (ACE) activity is increased in a var iety of disorders representing both early and late stages of atherosclerosi s. The factors governing the induction of vascular ACE are poorly understoo d. We hypothesized that vascular ACE activity might be increased by hyperte nsion-induced vessel distension. Hypertension was induced in rats by suprar enal coarctation of the aorta. Analyses were performed 5 days and 3 weeks p ost-operation. ACE activity and ACE mRNA level were increased in thoracic a ortae from coarctation hypertensive rats that had been exposed to elevated blood pressure, whereas they remained at normal level in abdominal aortae f rom those rats that had been exposed to normal blood pressure. The degree o f aortic BCE induction correlated well with the degree of the trans-stenoti c blood pressure gradient. An increase in ACE transcript level was also obs erved in carotid arteries from coarctation hypertensive rats that had been exposed to elevated blood pressure. In contrast, ACE activity and ACE mRNA expression were not altered in tissues that did not contain any large arter ies from coarctation hypertensive rats, although these tissues had been exp osed to elevated blood pressure. These results demonstrate an induction of ACE in large arteries that had been exposed to elevated blood pressure, and they imply that the induction of vascular ACE is due to hypertension-induc ed vessel distension.