title: Diaphragmatic adaptation following intra-abdominal weight changing.
abstract: BACKGROUND
  The diaphragm, the major respiratory muscle, contains three types of muscular fibers in dynamic balance between them. The fiber ratios vary in time in function of conditions, such as aging, hypoproteinemia, exercise, and chronic respiratory load. The diaphragmatic adaptation following abdominal conditions remains an unexplored field. This experimental study aims to identify the changes of the diaphragm due to chronic abdominal weight load. This may find application in conditions such as pregnancy, ascites, visceromegaly, large masses, and morbid obesity.
  
  
  METHODS
  Thirty rabbits were divided into control (A) and study (B) groups. Group B was loaded with weight for 2 months. The left costal hemidiaphragm were stained with H&E and ATPase (fiber typing), while the right underwent biochemical analysis (prooxidative-antioxidative balance, lipid peroxidation, superoxide dismutase, glutathione reductase and peroxidase activities, total glutathione, and protein carbonylation).
  
  
  RESULTS
  In H&E, all fibers were within normal range. ATPase analysis demonstrated reduction of type I (p = 0.019) and an increase of the type ΙΙ(Α) fibers ratio (p < 0.001) in group B, while the type ΙΙ(Β/X) fibers ratio remained stable. The above suggest remodeling of type I fibers into type II(A). Concerning biochemical analysis, difference was observed in glutathione peroxidase activity (p < 0.001).
  
  
  CONCLUSIONS
  Chronically loaded abdomen leads to morphological adaptations of the costal diaphragm, but with minor oxidative stress. These diaphragmatic morphological changes are equivalent to heart failure or severe COPD, showing that this remodeling makes the muscle more efficient towards work load, but more vulnerable to fatigue.
authors.affiliation: 3rd Department of Surgery, AHEPA University Hospital, Aristotle University of Thessaloniki, Aigaiou 6, 54655, Thessaloniki, Greece. Papavramidis@hotmail.com
authors.forename: Theodossis S
authors.initials: TS
authors.lastname: Papavramidis
authors.forename: Efstathios
authors.initials: E
authors.lastname: Kotidis
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Ioannidis
authors.forename: Angeliki
authors.initials: A
authors.lastname: Cheva
authors.forename: Thomai
authors.initials: T
authors.lastname: Lazou
authors.forename: George
authors.initials: G
authors.lastname: Koliakos
authors.forename: George
authors.initials: G
authors.lastname: Karkavelas
authors.forename: Spiros T
authors.initials: ST
authors.lastname: Papavramidis
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D003964:Diaphragm / Q000737:chemistry / Q000473:pathology*; D004195:Disease Models, Animal; D008297:Male; D056128:Obesity, Abdominal / Q000503:physiopathology*; D018384:Oxidative Stress; D011817:Rabbits; D015430:Weight Gain / Q000502:physiology