Related Experiment Videos
Influence of cigarette smoking on human autonomic function
O N Niedermaier1, M L Smith, L A Beightol
1Department of Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, Richmond, VA 23249.
Circulation
|August 1, 1993
Summary
Smoking acutely alters autonomic nervous system activity in habitual smokers. It reduces vagal activity and muscle sympathetic nerve activity but enhances sympathetic responses to blood pressure drops.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Research
- Smoking and Health
Background:
- Cigarette smoking is known to increase sympathetic nervous system activity.
- Limited data exists on smoking's direct impact on measured human sympathetic activity and its reflex control.
Purpose of the Study:
- To investigate the acute effects of smoking on muscle sympathetic nerve activity.
- To examine smoking's influence on arterial baroreflex control of sympathetic and vagal outflows.
Main Methods:
- Studied eight healthy habitual smokers smoking two research-grade cigarettes.
- Measured muscle sympathetic nerve activity during controlled breathing, Valsalva maneuvers, and carotid baroreceptor stimulation.
- Monitored arterial pressure, heart rate variability, and plasma nicotine and catecholamine levels.
Main Results:
- Smoking increased arterial pressure and plasma nicotine levels.
- Muscle sympathetic nerve activity and vagal cardiac activity decreased.
- Sympathetic responses to Valsalva straining and baroreflex alterations were observed.
Conclusions:
- Smoking acutely reduces baseline vagal activity and resets baroreflex responses in smokers.
- It decreases muscle sympathetic nerve activity but amplifies sympathetic responses to hypotension.
- These autonomic changes may significantly impact smokers' responses to acute blood pressure reductions.