The purpose of this study was to examine ambulatory blood pressure and heart rate patterns in healthy, normotensive adolescents and to determine the influence of race and gender on these patterns. Ambulatory blood pressure recordings were performed on 199 adolescents; 42 were black males, 55 were white males, 65 were black females, and 37 were white females. The mean age (±SD) was 13±2 years. Blood pressure readings were obtained with an automatic, noninvasive recorder. Black adolescents and white adolescents had similar blood pressures while awake (116/69 vs. 116/69 mm Hg), with boys having higher levels of systolic blood pressure (118 vs. 114 mm Hg) and comparable levels of diastolic blood pressure (69 vs. 69 mm Hg) relative to girls. The patterns while the adolescents were asleep, however, were different. White boys (106 mm Hg), white girls (105 mm Hg), and black girls (105 mm Hg) had similar systolic blood pressures during sleep. Black boys (112 mm Hg), however, had significantly higher systolic blood pressures while asleep. Black adolescents, as a group, had significantly higher diastolic blood pressures than white adolescents while asleep (64 vs. 61 mm Hg). Changes in blood pressure from awake to asleep were not related to changes in heart rate. Results of this study indicate that both race and gender are important determinants of the diurnal pattern of blood pressure and heart rate in adolescents. (Hypertension 1989;14:598-603)

After measuring blood pressure and heart rate at rest and during a video game procedure in 477 children enrolled in 3rd grade, 434 (91%) children had these measurements repeated a year later in 4th grade. Black children demonstrated greater blood pressure and heart rate reactivity than White children in both years, and an increase in heart rate reactivity from 3rd to 4th grade. Gender effects were inconsistent. Systolic and diastolic blood pressures during the video game were more highly correlated from year-to-year than were the resting measures. Regression analysis indicated that systolic reactivity was significantly related to subsequent systolic pressure at rest, particularly among Black girls. Diastolic reactivity was associated with subsequent resting diastolic pressure only among White children. Associations between reactivity and future blood pressure were independent of initial resting blood pressure. This study suggests that cardiovascular reactivity to psychological stress may be one important factor in future level of blood pressure and that the increased heart rate reactivity of Black children may be associated with the prevalence of hypertension among Black adults.

Cardiovascular reactivity to stress has been implicated as a marker and/or mechanism in the development of cardiovascular disease. No normative data exist to classify children's reactivity to psychological stress. This investigation presents normative percentile data on the hemodynamic responses (heart rate and blood pressure) of 310 healthy, black or white, children between the ages of 6 and 18 years to the stress of a television video game. A series of three video games, played under three increasing levels of stress, elicited progressively higher values of blood pressure and heart rate. Both the child's race and gender, as well as the experimenter's race, significantly affected reactivity. Children demonstrated a wide range of interchild reactivity, thus allowing separation of individuals into high and low risk percentile groups.

The influence of Na + excretion and race on casual blood pressure and ambulatory blood pressure patterns was examined in a biracial sample of healthy, normotensive children and adolescents (10-18 years; n=140). The slopes relating 24-hour urinary Na + excretion to systolic blood pressure were different for both black and white subjects for casual blood pressure (/><0.001) and blood pressure during sleep (/?<0.03). For casual blood pressure, the slope was significant for black subjects (/3=0.17;/»<0.001) but not for white subjects. For blood pressure during sleep, the slope was again significant for black subjects (/3=0.08; p<0.0l) but not for white subjects. Na + excretion was also related to awake levels of systolic blood pressure for black subjects (/3=0.08, r=0.36;/?<0.01), although the slopes for both black and white subjects were not significantly different. Further analyses indicated the results were not due to racial differences in 24-hour urinary K + excretion. However, plasma renin activity was marginally related to Na + excretion in white subjects (r=0.22; p<0.06) but not black subjects, a finding that is consistent with previous studies. Na + excretion was not associated with diastolic blood pressure or heart rate in either group under any condition. The results of this study support research that has demonstrated a stronger relation between Na + handling and casual blood pressure in black subjects and extend these findings to blood pressure while the subject is both awake and asleep. (Hypertension 1991;18:813-818) R ecent studies in both adolescents 1 and adults 2 ' 3 demonstrated that black subjects as a group had a "blunted" nocturnal decline in blood pressure (BP). Research has shown that Na + intake is a primary determinant of BP in a significant percentage of both the hypertensive 45 and normotensive 67 populations, a characteristic referred to as "salt sensitivity." Furthermore, the prevalence of salt sensitivity has been found to be greater in the black population than in the white population.4 -8 Therefore, the purpose of the present study was to examine the effect of sodium excretion (U Na V) and race on casual BP and ambulatory BP patterns in healthy black and white adolescents. In addition, K + excretion (U K V) 9 -U and plasma renin activity (PRA) 12 -16 were measured to determine the role of these factors that are known to influence Na + homeostasis and BP control.