Exaggerated sympathetic nervous system response to extended psychological stress in offspring of hypertensives.

The cardiovascular responses of 24 healthy young adult males with a parental history of hypertension and 24 males without a parental history of hypertension to an extended active-coping psychological stressor were compared under three drug conditions: placebo, the beta 1-blocking agent metoprolol, and the alpha 1-blocking agent prazosin. In the placebo condition, offspring of hypertensives exhibited significantly greater heart rate, blood volume pulse, and forearm blood flow responses to the task. They also exhibited a significantly greater initial decrease in forearm vascular resistance, which, in contrast to the offspring of normotensives, was no longer significantly different from baseline levels by the end of the session. No group differences in blood pressure response were observed. Metoprolol eliminated the differences in heart rate and forearm vascular resistance responses. Prazosin eliminated the difference in blood volume pulse response and elicited a sustained group difference in forearm vascular resistance. These results implicate the sympathetic nervous system in the exaggerated cardiovascular responsivity to psychological stress in individuals with a family history of essential hypertension. They also suggest that the pattern of increasing vascular resistance in response to this stressor observed in this and other studies in this laboratory reflects alpha-adrenergic activity and not neurohumorally independent autoregulation.