title: Ionic determinants of exhaled breath condensate pH before and after exercise in adolescent athletes.
abstract: BACKGROUND
  The pH of exhaled breath condensate (EBC) of adolescent athletes engaged in vigorous physical activity is low compared to healthy controls; however, the ionic determinants of EBC pH and the acute effects of exercise on those determinants have not been definitively established.
  
  
  OBJECTIVE
  This study had two purposes: (1) to identify the ionic composition of EBC before and after exercise, and (2) to examine the effects of sample deaeration on EBC pH and composition.
  
  
  METHODS
  EBC ionic composition was determined by ion chromatography and correlated with pH measured before and after deaeration. Bicarbonate concentration was calculated from the ion balance of other measured species and pH.
  
  
  RESULTS
  EBC pH displayed a bimodal distribution, included values lower than expected for healthy individuals, and was correlated exclusively with volatile species, namely ammonia (mean concentration = 215 microM) and acetic (31.7 microM) and propionic acids (10.0 microM). Following exercise, raw EBC pH and ammonia concentration increased while propionic acid concentration fell. Following deaeration, EBC pH increased by one unit on average; however, the pH of samples with unusually low pH did not change significantly, and the concentrations of several ionic species were altered in a manner that cannot be explained in terms of volatility.
  
  
  CONCLUSIONS
  We conclude that in healthy adolescents, exercise results in an acute increase in raw EBC pH in association with an increase in ammonium and a decrease in propionate concentration. Since exercise increases systemic ammonia and urea (which is hydrolyzed by oral bacteria to form ammonia), we propose that the likely source of these changes is gas-phase diffusion from epithelial and oral surface liquids and to a lesser extent, from pulmonary circulation.
authors: Division of Pulmonary, Allergy, Cystic Fibrosis, and Sleep Medicine, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA. roby.greenwald@emory.edu
authors: Roby
authors: R
authors: Greenwald
authors: Jill M
authors: JM
authors: Ferdinands
authors: W Gerald
authors: WG
authors: Teague
mesh_terms: D019342:Acetic Acid / Q000032:analysis; D000293:Adolescent; D000641:Ammonia / Q000032:analysis; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D002852:Chromatography, Ion Exchange; D015444:Exercise; D045853:Exhalation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000032:analysis; D011422:Propionates / Q000032:analysis
chemical_list: D002254:Carbonates; D007477:Ions; D011422:Propionates; D002245:Carbon Dioxide; D000641:Ammonia; D019342:Acetic Acid