title: Different biomechanical properties of medial and adventitial layers of thoracic aorta in Wistar-Kyoto and spontaneously hypertensive rats.
abstract: OBJECTIVE
  To evaluate the biomechanical properties of thoracic aorta with or without adventitia, and to determine whether there are corresponding changes with hypertension.
  
  
  METHODS
  Normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) at the age of 16 and 32 weeks were used. Thoracic aortic adventitial layer was mechanically separated from thoracic aorta and the adventitia-denuded artery ring was viewed as thoracic media. A load-strain curve was obtained by stretching the ring-shaped intact thoracic aorta or thoracic media with a tensile testing machine. Then, the slope of the load-stain curve at 30%-40% strains was viewed as the elastic stiffness at physiological load, whereas the slope near the breaking point was calculated as maximum stiffness. The maximum load is the load at the breaking point.
  
  
  RESULTS
  There was no significant difference in elastic stiffness and maximum stiffness of intact thoracic aorta between SHR and age-matched WKY. The elastic stiffness of intact thoracic aorta showed no significant difference from that of thoracic media in WKY and SHR at both ages. In contrast, both maximum stiffness and maximum load were reduced in thoracic media compared with intact thoracic aorta in SHR and WKY at both ages.
  
  
  CONCLUSIONS
  These results indicated that vascular adventitia contributes to maximum stiffness, but not elastic stiffness in both SHR and WKY.
authors.affiliation: Department of Hypertension, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, China.
authors.forename: Wei-qing
authors.initials: WQ
authors.lastname: Han
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Wu
authors.forename: Ding-liang
authors.initials: DL
authors.lastname: Zhu
authors.forename: Ping-jin
authors.initials: PJ
authors.lastname: Gao
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D001794:Blood Pressure; D003238:Connective Tissue / Q000503:physiopathology*; D004548:Elasticity; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013045:Species Specificity; D017540:Tunica Media / Q000503:physiopathology*
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