Voluntary aerobic exercise abolishes age‐associated arterial stiffening in mice: relation to collagen subtype expression in the medial and adventitial layers

Abstract

Voluntary aerobic exercise reduces large elastic artery stiffness with aging in humans, but it is unknown if reductions in collagen subtypes in the medial and/or adventitial layers of the arterial wall could be involved. Young (Y, 7 mo) and old (O, 31 mo) adult B6D2F1 mice underwent cage‐control (C) or voluntary wheel running (VR) for 12 weeks with carotid artery in vitro stiffness measures (n=9‐10/group) and immunohistochemical assessment of collagen (n=4‐8/group). VR (OVR: 3.7 ± 1.1 AU) abolished the age‐associated increase in passive stiffness in C animals (YC: 5.3 ± 0.8 vs. OC: 8.2 ± 1.0, P < 0.05). Collagen type I and III densities were 40‐55% greater in adventitia of OC vs. YC (P < 0.05), whereas OVR mice had medial and adventitial levels < OC (P < 0.05) and < YC. Collagen type IV was 30‐70% greater in media and adventitia of OC vs. YC (P < 0.05), whereas OVR had medial and adventitial levels < OC (P < 0.05) and < YC. Relative stiffness was not different in YC vs. YVR, and collagen expression was similar or lower in YVR. Short‐term voluntary aerobic exercise started late in life abolished the increase in carotid artery stiffness observed with sedentary aging in mice. Our data are the first to suggest a role for adventitial collagen deposition in age‐associated arterial stiffening, and that regular exercise may reduce stiffness in old mice in part by reducing collagen I, III and IV in the medial and adventitial layers of the arterial wall.NIH AG013038, AG006537, AG015897, AG029337, AG000279