A comparison of passive and active wall mechanics between elastic and muscular arteries of juvenile and adult rats

Abstract

The elastic abdominal aorta and muscular femoral artery are susceptible to aneurysm and atherosclerosis, respectively. The vessel wall mechanics should be an important element for the difference. The objective of the study is to demonstrate a comparison of vessel wall mechanics between elastic and muscular arteries of juvenile and adult rats to show the changes of mechanical properties relevant to aging. The passive and active mechanical tests, theoretical analysis, and histological evaluation were carried out to investigate mechanical properties of vessel walls in the abdominal aorta and carotid and femoral arteries of young and adult rats. There are stiffening femoral artery, unchanged carotid artery, and distensible abdominal aorta in adult rats as compared with the young. The opening angle has values of 54 ± 13°, 82 ± 13°, and 94 ± 13° in the abdominal aorta and carotid and femoral arteries of adult rats, respectively, as well as 80 ± 22°, 93 ± 19°, and 100 ± 23° in the young. The findings are explained by the significantly reduced width of collagen fibers in the abdominal aorta, relatively unchanged width in the carotid artery, and significantly increased width in the femoral artery of adult rats as compared with the young. In conjunction with available literatures, we concluded that inconsistency for nonlinear age-related changes of artery wall mechanics occurs between arteries of different types, which may be a risk factor for the occurrence of abdominal aorta aneurysm and femoral artery atherosclerosis.