Interaction of sodium sensitivity and stress in young adults. The interaction of sodium sensitivity and stress-induced cardiovascular reactivity was studied in white and black young adults aged 18-23 years. The cardiovascular response to difficult mental arithmetic was measured before and after 14 days of oral sodium loading (10 g NaCl/day added to the usual diet). A sodium-sensitive blood pressure response occurred in 18.4% of whites and 37.3% of blacks. A significant correlation between blood pressure change and sodium excretion occurred in the sodium-sensitive group (r = - 0.28, p less than 0.01). High sodium intake did not augment blood pressure or heart rate response to the beta-adrenergic-mediated stimulus of mental arithmetic in the population, which was grouped by blood pressure, race, or sodium sensitivity. 