title: Relation of murine thoracic aortic structural and cellular changes with aging to passive and active mechanical properties.
abstract: BACKGROUND
  Maintenance of the structure and mechanical properties of the thoracic aorta contributes to aortic function and is dependent on the composition of the extracellular matrix and the cellular content within the aortic wall. Age-related alterations in the aorta include changes in cellular content and composition of the extracellular matrix; however, the precise roles of these age-related changes in altering aortic mechanical function are not well understood.
  
  
  RESULTS
  Thoracic aortic rings from the descending segment were harvested from C57BL/6 mice aged 6 and 21 months. Thoracic aortic diameter and wall thickness were higher in the old mice. Cellular density was reduced in the medial layer of aortas from the old mice; concomitantly, collagen content was higher in old mice, but elastin content was similar between young and old mice. Stress relaxation, an index of compliance, was reduced in aortas from old mice and correlated with collagen fraction. Contractility of the aortic rings following potassium stimulation was reduced in old versus young mice. Furthermore, collagen gel contraction by aortic smooth muscle cells was reduced with age.
  
  
  CONCLUSIONS
  These results demonstrate that numerous age-related structural changes occurred in the thoracic aorta and were related to alterations in mechanical properties. Aortic contractility decreased with age, likely because of a reduction in medial cell number in addition to a smooth muscle contractile deficit. Together, these unique findings provide evidence that the age-related changes in structure and mechanical function coalesce to provide an aortic substrate that may be predisposed to aortopathies.
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC (J.B.W., R.M., R.E.S., J.A.J., J.S.I.).
authors.forename: Jason B
authors.initials: JB
authors.lastname: Wheeler
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC (J.B.W., R.M., R.E.S., J.A.J., J.S.I.).
authors.forename: Rupak
authors.initials: R
authors.lastname: Mukherjee
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC (J.B.W., R.M., R.E.S., J.A.J., J.S.I.).
authors.forename: Robert E
authors.initials: RE
authors.lastname: Stroud
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC (J.B.W., R.M., R.E.S., J.A.J., J.S.I.) Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC (J.A.J.).
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Jones
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC (J.B.W., R.M., R.E.S., J.A.J., J.S.I.).
authors.forename: John S
authors.initials: JS
authors.lastname: Ikonomidis
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D001018:Aortic Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D003094:Collagen / Q000378:metabolism; D003187:Compliance; D004549:Elastin / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000473:pathology; D059289:Vascular Stiffness; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation
chemical_list: D014662:Vasoconstrictor Agents; D003094:Collagen; D004549:Elastin
keywords: aging; aorta; compliance; contractility