Loss of Elastic Fiber Integrity Compromises Common Carotid Artery Function: Implications for Vascular Aging

Competent elastic fibers endow central arteries with the compliance and resilience that are fundamental to their primary mechanical function in vertebrates. That is, by enabling elastic energy to be stored in the arterial wall during systole and then to be used to work on the blood during diastole, elastic fibers decrease ventricular workload and augment blood flow in pulsatile systems. Indeed, because elastic fibers are formed during development and stretched during somatic growth, their continual tendency to recoil contributes to the undulation of the stiffer collagen fibers, which facilitates further the overall compliance of the wall under physiologic pressures while allowing the collagen to limit over-distension during acute increases in blood pressure. In this paper, we use consistent methods of measurement and quantification to compare the biaxial material stiffness, structural stiffness, and energy storage capacity of murine common carotid arteries having graded degrees of elastic fiber integrity - normal, elastin-deficient, fibrillin-1 deficient, fibulin-5 null, and elastase-treated. The finding that the intrinsic material stiffness tends to be maintained nearly constant suggests that intramural cells seek to maintain a favorable micromechanical environment in which to function. Nevertheless, a loss of elastic energy storage capability due to the loss of elastic fiber integrity severely compromises the primary function of these central arteries.