title: Impaired pressure natriuresis in obese youths.
abstract: OBJECTIVE
  To compare the response and recovery of blood pressure (BP) and sodium excretion (U(Na)V) in response to a behavioral stressor in overweight/obese and lean adolescents.
  
  
  METHODS
  Twenty-five lean (12% to 20% body fat) and 59 overweight/obese (>25% body fat) normotensive adolescents were provided all meals for 3 days (average sodium intake, 4000 +/- 200 mg/d), before performing the stressor on the third day. There was a 2-hour pre-stress rest, followed by a 1-hour stress (involving a video game task), and a 2-hour recovery. Percentage of body fat was obtained from DXA. U(Na)V was measured hourly, whereas systolic BP and diastolic BP measurements were obtained at 15-minute intervals, and averaged for each 1-hour period.
  
  
  RESULTS
  There was no significant difference between the lean and overweight/obese group for the response of systolic BP and diastolic BP (group by time interaction, p = 0.60 and p = 0.64, respectively). However, the lean group had a significantly greater increase in U(Na)V in response to the stressor compared with the overweight/obese group (p = 0.02). U(Na)V remained elevated compared with baseline in both groups at the 1-hour (p <or= 0.0001) and 2-hour (p <or= 0.0001) post-time points. Furthermore, there was a tendency for a larger number of sodium retainers in the overweight/obese group compared with the lean group (39.0% vs. 20.0%; chi(2) = 2.85, df = 1, p = 0.09).
  
  
  CONCLUSIONS
  This study provided evidence that sodium regulation was impaired during a behavioral stress in overweight/obese individuals compared with lean individuals.
authors.affiliation: Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, Georgia 30912, USA. pbarbeau@mail.mcg.edu
authors.forename: Paule
authors.initials: P
authors.lastname: Barbeau
authors.forename: Mark S
authors.initials: MS
authors.lastname: Litaker
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Harshfield
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001794:Blood Pressure; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D009318:Natriuresis; D009765:Obesity / Q000503:physiopathology*; D013315:Stress, Psychological / Q000503:physiopathology
chemical_list: D007328:Insulin