title: Acute exhaustive aerobic exercise training impair cardiomyocyte function and calcium handling in Sprague-Dawley rats.
abstract: Recent data from long-distance endurance participants suggest that cardiac function is impaired after completion. Existing data further indicate that right ventricular function is more affected than left ventricular function. The cellular mechanisms underpinning cardiac deterioration are limited and therefore the aim of this study was to examine cardiomyocyte and molecular responses of the right and left ventricle to an acute bout of exhaustive endurance exercise.
  
  
  
  Male Sprague-Dawley rats were assigned to sedentary controls or acute exhaustive endurance exercise consisting of a 120 minutes long forced treadmill run. The contractile function and Ca2+ handling properties in isolated cardiomyocytes, protein expression levels of sarcoplasmic reticulum Ca2+-ATPase and phospholamban including two of its phosphorylated states (serine 16 and threonine 17), and the mitochondrial respiration in permeabilized cardiac muscle fibers were analyzed.
  
  
  
  The exercise group showed a significant reduction in cardiomyocyte fractional shortening (right ventricle 1 Hz and 3 Hz p<0.001; left ventricle 1 Hz p<0.05), intracellular Ca2+ amplitude (right ventricle 1 and 3 Hz p<0.001; left ventricle 1 Hz p<0.01 and 3 Hz p<0.05) and rate of diastolic Ca2+ decay (right ventricle 1 Hz p<0.001 and 3 Hz p<0.01; left ventricle 1 and 3 Hz p<0.01). Cardiomyocyte relaxation during diastole was only significantly prolonged at 3 Hz in the right ventricle (p<0.05) compared to sedentary controls. We found an increase in phosphorylation of phospholamban at serine 16 and threonine 17 in the left (p<0.05), but not the right, ventricle from exhaustively exercised animals. The protein expression levels of sarcoplasmic reticulum Ca2+-ATPase and phospholamban was not changed. Furthermore, we found a reduction in maximal oxidative phosphorylation and electron transport system capacities of mitochondrial respiration in the right (p<0.01 and p<0.05, respectively), but not the left ventricle from rats subjected to acute exhaustive treadmill exercise.
  
  
  
  Acute exhaustive treadmill exercise is associated with impairment of cardiomyocyte Ca2+ handling and mitochondrial respiration that causes depression in both contraction and diastolic relaxation of cardiomyocytes.
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway.|K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway.
authors.forename: Kristine
authors.initials: K
authors.lastname: Ljones
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway.|K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway.
authors.forename: Henning Ofstad
authors.initials: HO
authors.lastname: Ness
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway.|K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway.
authors.forename: Karin
authors.initials: K
authors.lastname: Solvang-Garten
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway.|K. G. Jebsen Centre of Exercise in Medicine, Trondheim, Norway.
authors.forename: Svein Erik
authors.initials: SE
authors.lastname: Gaustad
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Technology and Science (NTNU), Trondheim, Norway.
authors.forename: Morten Andre
authors.initials: MA
authors.lastname: Høydal
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D019069:Cell Respiration; D002478:Cells, Cultured; D006321:Heart / Q000503:physiopathology; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002118:Calcium