A comparison of the effect of angiotensin converting enzyme inhibition and angiotensin II receptor antagonism on the structural changes associated with hypertension in rat small arteries

Abstract

To investigate whether, when angiotensin converting enzyme inhibitors are administered to young, genetically hypertension-prone animals, the demonstrated attenuation of blood pressure development and prevention of the structural changes usually observed in small arteries is attributable to the prevention of angiotensin II production. We have treated spontaneously hypertensive rats (SHR) aged 4-20 weeks with either lisinopril (1 or 10 mg/kg) or the angiotensin II receptor antagonist D 8731 (1, 20 or 50 mg/kg). Blood pressure was measured and structural parameters in small arteries from four vascular beds were examined using isometric myography. At age 20 weeks lisinopril had attenuated blood pressure development and prevented cardiac hypertrophy (but not vascular hypertrophy) in a dose-dependent manner. The highest dose of lisinopril had reduced the blood pressure of the SHR to below that of the Wistar-Kyoto (WKY) rats and prevented most structural changes, but there was a slight reduction in body weight in those rats. Comparable blood pressure control with D 8731 was associated with similar structural parameters. The prevention of hypertension-associated vascular structural alteration appears to be dependent upon the degree of blood pressure control.