Relationship of body composition to stress-induced pressure natriuresis in youth.
BACKGROUND
The contribution of stress to obesity-related cardiovascular disease is uncertain. The purpose of this study was to examine the influence of body composition on stress-induced pressure natriuresis.


METHODS
Dual energy x-ray absorptiometry was performed in 127 African American and white youths to assess lean body mass (LBM), fat mass (FM), and total percentage of body fat (%BF). The stress protocol was comprised of a 2-h baseline period, 1-h video game competition stressor, and 2-h recovery period. Blood and urine samples were collected hourly and blood pressure (BP) was obtained at 15-min intervals.


RESULTS
Both BP and urinary sodium excretion(U(Na)V) increased from baseline to stress and returned to prestress levels after stress (P = .001 for each). The BP levels and changes were positively correlated with LBM. In contrast, levels and changes in sodium excretion U(Na)V were inversely correlated with FM and %BM. Multiple regression analyses that included ethnicity, sex, angiotensin II (Ang II), and measures of body composition in the models indicated the following: a) LBM was the best predictor of stress systolic BP and independently contributed with ethnicity to stress diastolic BP; b) ethnicity was the only independent predictor of the stress-related change in systolic and diastolic BP; c) LBM was the only independent predictor of the change in BP from stress to recovery for both systolic and diastolic BP; and d) total percent body fat accounted for 11.2% of the variance of stress U(Na)V, with Ang II contributing an additional 6.1%.


CONCLUSIONS
Based on the results of this study, ethnicity and body composition are related to stress-induced pressure natriuresis.
Wilson
Martha E
ME
Georgia Prevention Institute and the Department of Pediatrics, Medical College of Georgia, Augusta, Georgia, USA.
Harshfield
Gregory A
GA
Ortiz
Luis
L
Hanevold
Coral
C
Kapuka
Gaston
G
Mackey
Lynne
L
Gillis
Delores
D
Edmonds
Lesley
L
Evans
Conner
C
D015502:Absorptiometry, Photon; D000293:Adolescent; D000804:Angiotensin II / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009318:Natriuresis / Q000502:physiology*; D009765:Obesity / Q000150:complications / Q000503:physiopathology; D044469:Racial Groups; D012737:Sex Factors; D012964:Sodium / Q000097:blood / Q000502:physiology / Q000652:urine; D013312:Stress, Physiological / Q000150:complications / Q000503:physiopathology*
D000804:Angiotensin II; D012964:Sodium