Effects of β1- and β2-blockade on blood pressure and sympathetic responses to flight phobia stress

Cardiovascular and sympathoadrenal effects of short-term oral treatment with β1-blockade (atenolol, 50 mg, administered two times) and β2-blockade (ICI 118,551, 50 mg, administered three times) were compared with placebo during actual flying in subjects with flight phobia (n = 34). β1-Blockade lowered resting blood pressure and heart rate and prevented a heart rate response but not a blood pressure response to this psychologic stress. β2-Blockade minimally lowered resting heart rate and prevented a heart rate response, but it failed to lower resting blood pressure or blood pressure response to the stress. Plasma epinephrine increased with all three treatments and more with β1-blockade than with placebo. Plasma norepinephrine decreased with administration of β2-blockade. Thus neither β1- nor β2-blockade prevents an increase in blood pressure during acute flight phobia stress. Increased plasma epinephrine seems to be the sympathetic variable that is closest related to this increase in blood pressure. Norepinephrine may be less consistently related to the blood pressure rise during flight phobia stress as shown by the decrease in plasma norepinephrine with administration of β2-blockade. Clinical Pharmacology and Therapeutics (1990) 47, 599–607; doi:10.1038/clpt.1990.81