Cholesterol enrichment of arteries may induce biochemical and structural abnormalities in vascular smooth muscle resulting in increased arterial contractile sensitivity. We studied the effects of a high-cholesterol diet on arterial structural properties and vascular reactivity in young rabbits. In vivo measurements of aortic intimal-plus-medial thickness using high resolution ultrasound imaging were obtained before and after 3 weeks of a high-cholesterol diet in 12 rabbits (group 2) and compared to data from 12 animals a cholesterol-free diet fed (group 1). Six rabbits (group 3) were studied before and after a 3-week, high-cholesterol diet and after a subsequent 13-week, cholesterol-free recovery diet. Blood pressure responsiveness to noradrenaline was evaluated before and at the end of each diet period. In groups 2 and 3, high dietary cholesterol caused an increase in intimal-plus-medial thickness from 0.31 mm and 0.33 mm to 0.88 mm and 0.89 mm, respectively (p less than 0.001). Plasma cholesterol concentration rose from 0.9 +/- 0.26 mmol/l to 36.7 +/- 8.56 mmol/l. There was no change in group 1. In group 3, intimal-plus-medial thickness remained increased (1.01 mm) following the cholesterol-free recovery diet despite normal plasma cholesterol. Blood pressure responsiveness to noradrenaline was markedly increased after the high-cholesterol diet (p less than 0.001) in groups 2 and 3 and after the cholesterol-free recovery diet in group 3 (p less than 0.001), and was directly related to intimal-plus-medial thickness (r = 0.84; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)