title: Short-term treadmill running as a model for studying cell-free DNA kinetics in vivo.
abstract: BACKGROUND
  Increased plasma concentrations of cell-free DNA (cf-DNA) are considered a hallmark of various clinical conditions. Despite intensive research in this field, limited data are available concerning the time course of release and clearance of cf-DNA in vivo.
  
  
  METHODS
  We extracted cf-DNA from plasma samples taken before and immediately after a 10-km cross-country run, and from samples taken before, immediately after, and 30 min after exhaustive short-term treadmill exercise. The contribution of nuclear (nDNA) and mitochondrial DNA (mtDNA) was measured by quantitative real-time PCR. The incremental treadmill exercise setup was exploited to delineate the precise sequencing and timing of cf-nDNA, lactate, and high-mobility group box 1 protein (HMGB1) release during the exercise and recovery phases.
  
  
  RESULTS
  Postexercise plasma cf-nDNA concentrations in cross-country and treadmill runners were significantly increased, by 7.6-fold and 9.9-fold, respectively (P < 0.001). cf-nDNA concentrations were not correlated with age, sex, or body mass index. Plasma concentrations of cf-nDNA and HMGB1 in postexercise samples of treadmill runners were significantly correlated (r = 0.84; P = 0.004). cf-mtDNA concentrations were not affected by treadmill exercise. Time-course analyses demonstrated that cf-nDNA is released within minutes after the onset of exercise and is rapidly cleared from the circulation after the cessation of exercise. Nearly congruent kinetics for cf-nDNA, lactate, and HMGB1 were observed during the exercise phase.
  
  
  CONCLUSIONS
  A single bout of exhaustive short-term treadmill exercise constitutes a versatile model system suitable for addressing basic questions about cf-DNA biology.
authors.affiliation: Department of Sports Medicine, Eberhard-Karls-University of Tuebingen, Tuebingen, Germany. thomas.beiter@med.uni-tuebingen.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Beiter
authors.forename: Annunziata
authors.initials: A
authors.lastname: Fragasso
authors.forename: Jens
authors.initials: J
authors.lastname: Hudemann
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Niess
authors.forename: Perikles
authors.initials: P
authors.lastname: Simon
mesh_terms: D000293:Adolescent; D000328:Adult; D002474:Cell-Free System; D004247:DNA / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D012420:Running; D055815:Young Adult
chemical_list: D004247:DNA