Ethnic differences in hemodynamic responses to stress in hypertensive men and women.

Hemodynamic response patterns to three laboratory stressors were compared in 63 mildly hypertensive black and white men and women. Ethnic groups were matched for age, body mass index, and casual blood pressures. Stressors included a mental arithmetic task, a simulated public speaking task, and a forehead cold pressor test. Blood pressure increases during the stressors were similar in the two ethnic groups. However, the pressor responses were mediated by greater vascular tone in black compared to white subjects. These differences persisted whether the hemodynamic response pattern was associated with an overall fall (speech task) or rise (cold pressor) in systemic vascular resistance. Gender differences in the hemodynamic basis of pressor responding were also observed. Women, compared to men, exhibited greater increases in heart rate and smaller vascular contributions to their blood pressure increases during stress. Ethnic and gender differences are discussed in terms of the neurohumoral mechanisms mediating the cardiovascular stress response. The findings are consistent with converging evidence suggesting that beta-adrenergic receptor down-regulation is characteristic of hypertension in whites, whereas heightened vascular alpha-receptor sensitivity or early vascular hypertrophy may be a feature of hypertension in blacks.