The association of race and sex to the pressure natriuresis response to stress

Objective: Sympathetic nervous system activation promoting sodium retention has long been recognized to play a significant role in the development and maintenance of salt-sensitive hypertension. The purpose of this study was to examine the influence of race and sex on the pressure natriuresis response to prolonged behavioral stress in youth. Methods: The 190 subjects included 94 boys (41 African American, 53 Caucasian) and 96 girls (44 African American, 52 Caucasian) of similar age (17-19 years). The stress test was composed of a one hour competitive video game task preceded and followed by two-hour rest periods. Blood pressure (BP) was obtained at 15 minute intervals and sodium excretion (U_NaV) was measured hourly. The general linear model was used to model the effects of race, sex, and their interaction on the variables of interest. Results: Caucasians, compared to African Americans, had a greater change in U_NaV (F[1,183]=5.28, P=.0227), as did boys compared to girls (F[1,183]=5.72, P=.0178), with no interaction between race and sex. The race-by-sex interaction was significant for the change in systolic BP (F[1,183]=5.66, P=.0184), with Caucasian girls showing a smaller change than the other three race/sex groups. Conclusion: African Americans have a reduced natriuretic response to stress, which may be a marker or mechanism for the development of salt-sensitive hypertension in this population. The race difference within girls is of interest and requires further investigation.