<Original article>The Preventive Effect of β-blockers, Carvedilol and Metoprolol, on Mental Stress-induced Changes in Cardiovascular Functions by a Color Word Conflict Test

Experimental mental stress by a computerized color word conflict test was developed. The effects of a single oral administration of two different β-blockers, carvedilol (a vasodilating β-/α_1-blocker, 20 mg) and metoprolol (a β_1-selective blocker, 20 mg), on a color word conflict test (mental stress)-induced increase in heart rate and systolic blood pressure were investigated in 108 healthy volunteers, 21-24 years of age, by double blind protocol. At rest carvedilol and metoprolol gradually reduced the heart rate, and slightly lowered systolic and diastolic blood pressure. The mental stress by the color word conflict test significantly increased the heart rate and systolic blood pressure by a respective 3.1±0.6/min and 2.0±0.9mmHg. Carvedilol completely inhibited the mental stress-induced increases in both systolic blood pressure and heart rate 3 h after administration, and metoprolol significantly blocked the increase in systolic blood pressure. These findings indicated that β-blockers effectively prevent mental stress-induced changes in cardiovascular functions.