To evaluate the reactivity to psychological stress in patients with essential hypertension we investigated hemodynamic and endocrinologic changes during a mental arithmetic task (MAT) and a mirror drawing test (MDT) in 10 hypertensive subjects. Hemodynamic changes were assessed continuously using an ambulatory radionuclide cardiac detector. There were significant increases in systolic blood pressure (ΔSBP: +37.8 +/- 11.1 and +41.0 +/- 9.4 mm Hg during MAT and MDT, respectively, P < .01) and diastolic blood pressure (ΔDBP: +17.5 +/- 3.1 and +21.2 +/- 3.9 mm Hg, P < .01) and in heart rate (ΔHR: +17.1 +/- 5.3 and +12.5 +/- 2.9 beats/min, P < .01) during both tasks in association with an increase in cardiac output (CO). The plasma levels of norepinephrine and epinephrine increased during both the MAT (ΔNE: +0.074 +/- 0.022 ng/mL, P < .01; ΔEP: +0.068 +/- 0.025 ng/mL, P < .01) and the MDT (ΔNE: +0.067 +/- 0.034 ng/mL, P < .01; ΔEP: +0.030 +/- 0.011 ng/mL, .05 < P < .1). Although the ΔNE was similar in response to the MAT and MDT, the ΔEP during the MDT tended to be less than half the ΔEP during the MAT (.05 < P < .10). The ΔEP was positively correlated with the ΔDBP and the ΔCO during both tasks and with the ΔSBP and the ΔHR during the MAT. These findings suggest that MAT- and MDT-induced increases in BP were attributable mainly to an increase in CO, possibly as the result of stimulation of the sympathoadrenomedullary system. However, the sympathoadrenomedullary system appeared to be more closely associated with the hemodynamic responses during the MAT than during the MDT.