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(Na)V) 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(Na)V (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.