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

Objective: 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. Design: 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). Methods: Blood pressure was measured and structural parameters in small arteries from four vascular beds were examined using isometric myography. Results: 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. Conclusion: The prevention of hypertension-associated vascular structural alteration appears to be dependent upon the degree of blood pressure control.