title: Morphologic and biomechanical changes of thoracic and abdominal aorta in a rat model of cigarette smoke exposure.
abstract: BACKGROUND
  Smoking is the most relevant environmental factor that affects the development of aortic aneurysm. Smokers have elevated levels of elastase activity in the arterial wall, which leads to weakening of the aorta. The aim of this study was to verify whether cigarette smoke exposure itself is capable of altering the aortic wall.
  
  
  METHODS
  Forty-eight Wistar rats were divided into 2-, 4-, and 6-month experimental periods and into 2 groups: smokers (submitted to smoke exposure at a rate of 40 cigarettes/day) and nonsmokers. At the end of the experimental periods, the aortas were removed and cross-sectioned to obtain histologic specimens for light microscopic and morphometric analyses. The remaining longitudinal segments were stretched to rupture and mechanical parameters were determined.
  
  
  RESULTS
  A degenerative process (i.e., a reduction in elastic fibers, the loss of lamellar arrangement, and a reduction of smooth muscle cells) was observed, and this effect was proportional in intensity to the period of tobacco exposure. We observed a progressive reduction in the yield point of the thoracic aorta over time (P < 0.05). There was a decrease in stiffness (P < 0.05) and in failure load (P < 0.05) at 6 months in the abdominal aorta of rats in the smoking group.
  
  
  CONCLUSIONS
  Chronic exposure to tobacco smoke can affect the mechanical properties of the aorta and can also provoke substantial structural changes of the arterial wall.
authors.affiliation: Department of Surgery and Orthopaedics, São Paulo State University Medical School, Botucatu, Brazil. rgibin@fmb.unesp.br
authors.forename: Rodrigo Gibin
authors.initials: RG
authors.lastname: Jaldin
authors.forename: Édson
authors.initials: É
authors.lastname: Castardelli
authors.forename: Juliana Elaine
authors.initials: JE
authors.lastname: Perobelli
authors.forename: Winston Bonetti
authors.initials: WB
authors.lastname: Yoshida
authors.forename: Antônio
authors.initials: A
authors.lastname: de Castro Rodrigues
authors.forename: Júlio Lopes
authors.initials: JL
authors.lastname: Sequeira
authors.forename: Sérgio Alberto Rupp
authors.initials: SA
authors.lastname: Paiva
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000473:pathology* / Q000503:physiopathology; D001013:Aorta, Thoracic / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D004548:Elasticity; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012907:Smoking / Q000473:pathology / Q000503:physiopathology*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution