The regressive effect of an angiotensin II receptor blocker on formed fatty streaks in monkeys fed a high-cholesterol diet

OBJECTIVES: To clarify the regressive effect of an angiotensin II type 1 receptor blocker (ARB) on already formed fatty streaks, we investigated the effect of the administration of an ARB, olmesartan, on formed fatty streaks in monkeys fed a high-cholesterol diet. METHODS: After the monkeys were fed a high-cholesterol diet for 6 months, intimal hyperplasia was clearly observed on intravascular ultrasound. For the next 6 months, the high-cholesterol diet was continued, and olmesartan (3 mg/kg per day) or placebo was administered. A control group was fed a normal diet for 12 months. RESULTS: Olmesartan did not significantly affect blood pressure or plasma cholesterol levels throughout the experiment. After 6 months of treatment with olmesartan, intimal hyperplasia was significantly lower than before treatment. Acetylcholine-induced relaxation in isolated carotid arteries was significantly less in the high-cholesterol diet placebo-treated group compared to the normal diet group, whereas its response was improved by olmesartan. Serum levels of monocyte chemoattractant protein were significantly increased with a high cholesterol load, but they were significantly suppressed by olmesartan. CONCLUSIONS: We have demonstrated for the first time that an ARB, olmesartan, was found to have a regressive effect on formed fatty streaks in monkeys.