title: Acute exercises induce disorders of the gastrointestinal integrity in a murine model.
abstract: OBJECTIVE
  Many endurance athletes complain about gastrointestinal (GI) symptoms. It is assumed that exercise-induced shift of perfusion with consecutive hypoperfusion of the enteral vascular system leads to an increased GI permeability and tissue damage. Therefore, the aim of the study was to investigate permeability, apoptosis, electrogenic ion transport (Isc), and tissue conductance (Gt) of the small intestine in a murine exercise model.
  
  
  METHODS
  After spirometry, male Swiss CD-1 mice were subjected to an intensive treadmill exercise (80% VO2max). Sedentary mice served as controls. The small intestine was removed at several time intervals post-exercise. Apoptotic cells were determined by the TUNEL method, while fluorescein isothiocyanate dextran permeation indicated intestinal permeability. The Gt and Isc measurements were carried out in a modified Ussing chamber.
  
  
  RESULTS
  Apoptosis of epithelial cells increased continuously until 24 h post exercise (0.8 ± 0.42 versus 39.2 ± 26.0%; p < 0.05). Compared with the control group the permeability increased 2 h after exercise (0.47 ± 0.07 versus 0.67 ± 0.14 FU/min; p < 0.05). Isc measurements of the ileum were augmented after 24 h (3.33 ± 0.56 versus 5.77 ± 1.16 μEq/h/cm(2); p < 0.05). At this time the Gt increased as well (28.8 ± 3.37 versus 32.5 ± 2.59 mS/cm(2); p < 0.05).
  
  
  CONCLUSIONS
  In the murine exercise model there is evidence that after intense endurance exercise repair processes occur in small intestinal epithelial cells, which affect permeability, Gt, and Isc. The formation of lamellipodia to close the "leaky" tight junctions caused by apoptosis might be an underlying mechanism.
authors.affiliation: Department of Sports Medicine, Institute of Sports Sciences, Justus-Liebig-University, Giessen, Germany, gutekunst@sport.uni-frankfurt.de.
authors.forename: Katrin
authors.initials: K
authors.lastname: Gutekunst
authors.forename: Karsten
authors.initials: K
authors.lastname: Krüger
authors.forename: Christian
authors.initials: C
authors.lastname: August
authors.forename: Martin
authors.initials: M
authors.lastname: Diener
authors.forename: Frank-Christoph
authors.initials: FC
authors.lastname: Mooren
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D005767:Gastrointestinal Diseases / Q000503:physiopathology*; D007421:Intestine, Small / Q000503:physiopathology; D017136:Ion Transport / Q000502:physiology; D008297:Male; D051379:Mice; D010539:Permeability; D010805:Physical Conditioning, Animal / Q000009:adverse effects* / Q000502:physiology*