Meeting Abstract

148.6  Monday, Jan. 7  Stiffness of Mouse Aortic Elastin and its Possible Relation to Aortic Media Structure ARMSTRONG, T E*; LILLIE, M A; SHADWICK, R E; Univ. of British Columbia; Univ. of British Columbia; Univ. of British Columbia trishaarm@gmail.com

Aortic elastin allows arterial expansion on systole and subsequent elastic recoil during diastole, providing crucial capacitance and associated dampening of the cardiac pressure pulses. The structure and mechanical properties of the aortic wall are not uniform along its length due to the varying hemodynamic conditions to which it is exposed, but elastin’s contributions to this variation are not well studied. The artery wall is a composite of two main structural proteins: elastin and collagen. Autoclaving an intact aorta removes the collagen and produces a mechanically competent vessel consisting of purified elastin, which can be used to study elastin’s contribution to arterial mechanics. Although it is generally assumed that elastin’s material stiffness is constant, a recent study in pigs found that it increased 30% along the thoracic aorta. We hypothesize that this increase in elastin stiffness is caused by a difference in the orientation of the elastic lamellae (EL) or in the EL connections to interlamellar elastin fibres (IEL) and smooth muscle cells. Uniaxial tensile testing of autoclaved mouse aortas showed elastin’s stiffness also varies along both the thoracic and abdominal aortas in mice, allowing the mouse aorta to be used as a model to investigate this surprising variation in elastin stiffness. Elastin structure within the thin mouse aortic walls is being imaged with multiphoton laser scanning microscopy to identify any variation in the EL or IEL structure that could cause the variation in stiffness.