Effect of mental stress on baroreceptor-mediated changes in blood pressure and heart rate and on plasma catecholamines and subjective responses in healthy men and women.

The aim of this study was to determine whether carotid sinus baroreceptor reflexes are impaired by moderate mental stress. In 12 healthy subjects (6 men, 6 women) baroreceptors were stimulated by static neck suction (at -40 mm Hg) for repeated 2-minute periods during mental stress and control conditions. Heart rate, arterial blood pressure, and levels of plasma catecholamines were measured, and self-reports of effort and distress were obtained. Mental stress, which was induced by a color-word conflict task, increased mean levels of heart rate (+12.4 beats/min; p less than 0.001) and systolic blood pressure (+11.8 mm Hg; p; less than 0.001). The onset of mental stress induced increases in plasma adrenaline and noradrenaline concentrations of 45.8% (p less than 0.08) and 17.6% (p less than 0.05), respectively. The increase in systolic blood pressure was significantly greater in men than in women (p less than 0.01). During mental stress, men had significantly higher levels of plasma adrenaline (p less than 0.05). In both sexes neck suction induced a significant decrease in heart rate and systolic blood pressure; these effects were essentially the same during mental stress and control. The results suggest that nonspecific mental stress does not substantially influence the ability of carotid sinus baroreceptors to decrease heart rate or blood pressure in response to sustained changes in baroreceptor input. The possibility that transient changes influence reflex activity is discussed.