Original Contribution
Am J Hypertens (2004) 17, 1023–1028; doi: 10.1016/j.amjhyper.2004.05.007
Relationship of body composition to stress-induced pressure natriuresis in youth*
Martha E. Wilson1, Gregory A. Harshfield1,2, Luis Ortiz1, Coral Hanevold1, Gaston Kapuka1, Lynne MacKey1, Delores Gillis1, Lesley Edmonds1 and Conner Evans1
- 1Georgia Prevention Institute and the Department of Pediatrics, Medical College of Georgia, Augusta, Georgia
- 2Department of Physiology, Medical College of Georgia, Augusta, Georgia
Correspondence: Dr. Gregory A. Harshfield, Medical College of Georgia, MCG Annex H.S. 1640, Augusta, GA 30912-4534 E-mail: Gharshfi@mail.mcg.edu
*This study was supported by grants HL-59954 and HL-64225 from the National Institutes of Health and HL069999 from the National Heart, Lung, and Blood Institute.
Received 18 December 2003; Revised 24 May 2004; Accepted 29 May 2004.
Abstract
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(UNaV) 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 UNaV 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 UNaV, 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.
Keywords:
Lean body mass, blood pressure, stress, race, pressure natriuresis
