Abstract-Mice lacking ApoE (Apoe -/-) develop initially hypercholesterolemia and latterly atherosclerosis. This study examined hemodynamics and endothelial function in 6-week-old Apoe -/-mice with hypercholesterolemia only, 7.5-months-old Apoe -/-mice with both hypercholesterolemia and atherosclerosis, and age matched controls. One day after implantation of catheters into the carotid artery, arterial pressure was measured in conscious, unrestrained mice. Compared with the respective controls, there was a significant increase in arterial pressure and the ratio of left ventricular weight to body weight in 7.5-month-old Apoe