title: Age is a risk factor for maladaptive changes of the pulmonary root in rats exposed to increased pressure loading.
abstract: BACKGROUND
  Pulmonary artery root does not adapt properly when exposed to increased pressure stress, with progressive dilatation. The aim of this study was to evaluate, in an animal model, the histologic changes of the pulmonary root wall under increased pressure load.
  
  
  RESULTS
  To increase the systolic pressure in the pulmonary root, a banding of the pulmonary artery (PAB) was performed in 10 adult Sprague-Dawley rats and in 10 weanlings, using 7 adults and 8 weanlings as controls. We analyzed the structural changes of the pulmonary artery root after 30 days of increased pressure load. The mean pressure gradient across the banded pulmonary trunk was 53.57 ± 10 mmHg in the adult rats and 86.73 ± 15 mmHg in the weanlings. The pulmonary artery wall was significantly thicker in both age groups of PAB rats when compared to age-matched controls, showing also architectural structural changes, as a higher degree of mucoid degeneration, medionecrosis, and fibrosis as well as elastic fibers fragmentation. The apoptotic index was also increased in both PAB age groups. We also confirmed the physiologic higher degree of elastic fibers disarray in adult rats when compared to weanlings.
  
  
  CONCLUSIONS
  The pulmonary artery wall seems to present maladaptive architectural changes in the media when exposed to systemic pressure. The PAB-related increase of the apoptotic index seems to reflect an accelerated involution of the pulmonary root's media. The physiologic higher degree of elastic fibers disarray in adult rats can possibly influence the worst adaptation of the pulmonary arterial wall to a systemic pressure load.
authors.affiliation: Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua Medical School, Padua, Italy. vladimiro.vida@unipd.it
authors.forename: Vladimiro L
authors.initials: VL
authors.lastname: Vida
authors.forename: Stefania
authors.initials: S
authors.lastname: Rizzo
authors.forename: Nicola
authors.initials: N
authors.lastname: Maschietto
authors.forename: Giovanna
authors.initials: G
authors.lastname: Boccuzzo
authors.forename: Ornella
authors.initials: O
authors.lastname: Milanesi
authors.forename: Gaetano
authors.initials: G
authors.lastname: Thiene
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stellin
authors.forename: Cristina
authors.initials: C
authors.lastname: Basso
mesh_terms: D000367:Age Factors; D000818:Animals; D017209:Apoptosis; D001794:Blood Pressure; D003251:Constriction, Pathologic / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D004547:Elastic Tissue / Q000473:pathology; D005355:Fibrosis / Q000473:pathology; D008026:Ligation; D008297:Male; D009077:Mucins / Q000378:metabolism; D009336:Necrosis / Q000473:pathology; D011651:Pulmonary Artery / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012307:Risk Factors; D013314:Stress, Mechanical; D017540:Tunica Media / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology
chemical_list: D009077:Mucins