When apoE-/- mice are fed a Western-type diet to accelerate and aggravate hypercholesterolemia and atherosclerosis, the vasodilation response to ACh in the aortas [23,64,65] and carotid arteries [23] of ~20-30-week-old males is normal; however, studies have shown a significant impairment of the vasodilation response to ACh in 14-15-week-old male [22,65,68-76] and female [4,19,77] mice. This evidence concerns the gene APOE and familial hypercholesterolemia.