In vivo assessment of endothelial function in rabbits. Change in the area of the abdominal aorta in response to acetylcholine infusions. Rabbits (n = 8) were fed with a cholesterol diet for the indicated period of time. The endothelial function was assessed before (week 0) and after 2 (week 2) and 8 (week 8) of hypercholesterolemia. Rabbits under sedation were serially infused for two minutes (saline (vehicle); 1 ml/min) in the marginal ear vein with the vehicle (left), acetylcholine (Ach) at 0.05 and at 0.5 mg/ml/min. *: P < 0.05 vs. vehicle and ¶ P < 0.05 vs Week 0.