Beta-adrenergic blockade in stress protection. Limited effect of metoprolol in psychological stress reaction.

In a model system the influence of mental stress on blood pressure and heart rate was studied in normal persons and in patients with hypertension (WHO grade III). Metoprolol was employed to investigate the preventive effect of beta-adrenergic blockade on the response to stress. In all groups blood pressure increased significantly during mental stress. The effect was not inhibited by metoprolol. The rise in heart rate, however, was depressed by beta-blockade. Reaction time, opticomotor coordination and concentration ability were studied as parameters of vigilance, but no significant difference between the metoprolol and control groups were observed. Thus, metoprolol only influenced the heart rate in mental stress and it did not affect vigilance.