Angiotensin-converting Enzyme: Induction by Hypertension-induced Vessel Distension

Abstract

Vascular angiotensin-converting enzyme (ACE) activity is increased in a variety of disorders representing both early and late stages of atherosclerosis. The factors governing the induction of vascular ACE are poorly understood. We hypothesized that vascular ACE activity might be increased by hypertension-induced vessel distension. Hypertension was induced in rats by suprarenal coarctation of the aorta. Analyses were performed 5 days and 4 weeks post-operation. ACE activity and ACE mRNA level were increased in thoracic aortae from coarctation hypertensive rats that had been exposed to elevated blood pressure, whereas they remained at normal level in abdominal aortae from those rats that had been exposed to normal blood pressure. The degree of aortic ACE induction correlated well with the degree of the trans-stenotic blood pressure gradient. An increase in ACE transcript level was also observed 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 arteries from coarctation hypertensive rats, although these tissues had been exposed 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-induced vessel distension.