Urinary catecholamines in habitual smokers and non-smokers.

1. There is no significant difference between habitual-smokers and non-smokers in the incidence of cardiovascular hyperreactivity to smoking. 2. The resting level of urinary catecholamines is somewhat raised in the smoker group particularly in the hyperreactors. 3. Smoking 20 cigarettes caused a higher rise in urinary catecholamines in the hyperreactors of both groups than in the normoreactors. 4. Hypertensive patients exhibited the most exaggerated rise in both the cardiovascular response to smoking and in urinary catecholamines.