Stress profile in essential hypertension.

This study was undertaken to test the hypothesis that basal sympathetic activity and sympathetic reactivity to stress are increased in patients with essential hypertension. One hundred and fifteen randomly selected patients with essential hypertension and an equal number of age- and sex-matched normal controls were included in this study. Various parameters, viz., heart rate, respiratory rate, blood pressure, peripheral skin temperature, electromyographic activity of the frontalis muscle, skin conductance (measured by electrodermography), and blood pressure, were measured in the resting state in both groups. These parameters were then measured during the performance of various stressful activities, such as mental arithmetical calculations, thinking of unpleasant thoughts, staring at a fixed point, catching of a dropped object, and reading aloud for 1 min each, and again over a 1-min quiet period following each stressful activity. Changes in various parameters in the two groups were analyzed and compared. Baseline heart rate, respiratory rate, electromyographic activity and peripheral skin temperature were higher-while skin conductance was lower-in the hypertensive group than in the control group. The increases in systolic blood pressure, diastolic blood pressure, heart rate, respiratory rate, electromyographic activity, and peripheral skin temperature in response to stress were greater in hypertensive patients than in controls, while skin conductance showed a higher elevation in controls than in hypertensive patients. In conclusion, sympathetic nervous system activity is increased in patients with essential hypertension. The reduced skin conductance and high peripheral skin temperature in these patients may be due to a possible dermal neurovascular dysfunction.