Smoking induced differences in autonomic responses in military pilot candidates.

The effects of smoking on autonomic function, the renin-angiotensin-aldosterone system, plasma catecholamine and 11-dehydro-thromboxane B2 values were studied in 37 young male military pilot candidates, 19 smokers and 18 non-smokers. There was a higher diastolic blood pressure at rest and higher systolic blood pressure after 5 min during the orthostatic test in smokers. Smokers also had higher diastolic blood pressure levels after exercise in the hand-grip test. Smokers had a lower Valsalva ratio and higher tachycardia ratio in the modified Valsalva manoeuvre, suggesting a degree of autonomic dysfunction. Plasma renin levels at rest and plasma noradrenaline levels after hand-grip test were significantly higher in smokers, implying increased sympathetic activity and enhanced activation of the renin-angiotensin system. Our findings indicate that smoking in fit young men increases sympathetic activity and changes physiological responses to autonomic tests.