Author + information
- Received October 31, 2000
- Revision received June 26, 2001
- Accepted August 10, 2001
- Published online November 15, 2001.
- Shoshana Zevin, MD*,
- Sandra Saunders, MD†,
- Steven G Gourlay, MBBS, PhD†,‡,
- Peyton Jacob III, PhD† and
- Neal L Benowitz, MD*,† ()
- ↵*Reprint requests and correspondence: Dr. Neal L. Benowitz, Chief, Division of Clinical Pharmacology and Experimental Therapeutics, University of California, San Francisco, Box 1220, San Francisco, California 94143-1220 USA
This study was designed to compare the effects of inhaled carbon monoxide (CO), administered to achieve concentrations similar to those found in cigarette smoking, with the effects of cigarette smoking and air inhalation on heart rate and blood pressure, catecholamine release, platelet activation and C-reactive protein (CRP), a marker of inflammation.
Carbon monoxide may contribute to smoking-induced cardiovascular disease. Exposure to environmental CO has been associated with increased cardiovascular morbidity and mortality. Animal and in vitro studies suggest that CO may contribute to atherosclerosis and endothelial injury. There is conflicting evidence about the hemodynamic consequences of exposure to CO and its role in platelet activation.
In a single-blind, crossover design, 12 healthy smokers inhaled CO at 1,200 ppm to 1,500 ppm to simulate CO intake from cigarette smoking, inhaled air on a similar schedule and smoked 20 cigarettes per day, each for seven days. Mean carboxyhemoglobin was 5 ± 1% on CO treatment, 6 ± 1% while smoking and 0.4 ± 0.2% on air inhalations.
There was no difference in blood pressure between the treatments. Mean heart rate was higher during cigarette smoking compared with CO and air inhalations (75 beats/min vs. 66 beats/min; p < 0.05). Plasma levels of platelet factor 4 and CRP and urine epinephrine and norepinephrine were higher while smoking, with no effect of CO compared with air.
Carbon monoxide administered under conditions similar to those of cigarette smoking had no significant effect on blood pressure, heart rate, plasma catecholamines, platelet aggregation or CRP. The short-term chronotropic effect, adrenergic-activating, platelet-activating and CRP-increasing effects of smoking in healthy smokers are probably due to components of cigarette smoke other than CO.
☆ Supported by U.S. Public Health Service grants DA02277 and DA12393 from the National Institute on Drug Abuse, National Institutes of Health, and a gift from Sano Corporation. Carried out in part at the General Clinical Research Center at San Francisco General Hospital Medical Center with support of the Division of Research Resources, National Institutes of Health (RR-00083). Dr. Saunders was supported by National Research Service Award T32 GM07546 from the National Institutes of Health. Dr. Gourlay was supported by a National Heart Foundation of Australia Overseas Research Fellowship.
- Received October 31, 2000.
- Revision received June 26, 2001.
- Accepted August 10, 2001.
- American College of Cardiology