Impaired Stress-Induced Pressure Natriuresis Is Related to Left Ventricle Structure in Blacks

Abstract

The mechanisms through which stress may contribute to the racial difference in the prevalence of essential hypertension and associated target organ damage remain unclear. This study examined differences in stress-induced pressure natriuresis in 69 black and 52 white normotensives age 14 to 27 years, all with a positive family history of hypertension. Urine samples for sodium excretion were collected before and after a series of tasks (video game challenge, forehead cold stimulation). The average blood pressure across the 2 tasks and the average increase in blood pressure to the 2 tasks were calculated. Blacks had higher mean systolic (131±12 versus 126±12 mm Hg, P <0.02) and diastolic (77±8 versus 72±9 mm Hg, P <0.001) blood pressure and a greater average change in systolic blood pressure (15±9 versus 11±7 mm Hg, P <0.04). This was associated with a smaller change in sodium excretion (2±6 versus 7±10 mEq/h, P <0.002). The change in sodium excretion was related to the change in systolic ( r =0.31, P <0.03) and diastolic ( r =0.27, P <0.05) blood pressure in whites but not in blacks. Relative wall thickness was greater in blacks (0.31±0.04 versus 0.29±0.03, P <0.002). In conclusion, impaired stress-induced pressure natriuresis in blacks may contribute to racial differences in essential hypertension and its sequelae.