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Hookah Smoking, Carbon Monoxide, and Coronary Endothelial Function

Principal Investigator: Ronald G. Victor

Funding Mechanism: National Institutes of Health - Grant

ID Number: 1 R21 DA041596-01A1

Award Date: 4/26/2017

Institution: Cedars-Sinai Medical Center

Because hookah tobacco is heated with burning charcoal, hookah smoke contains charcoal combustion products including carbon monoxide (CO) and oxidants that can clog coronary arteries. The CO level associated with hookah use decreases oxygen delivery to the heart unless it is offset by increased blood flow. The goals of this study are: (1) in young healthy hookah smokers, to test if CO dilates the heart’s arteries, thereby masking a tobacco-induced impairment; and (2) in long-term middle-aged hookah smokers, to test: (a) whether the coronary endothelium (the tissue lining the heart’s arteries) has become too dysfunctional to respond to CO in hookah smoke, thereby indicating impaired blood flow to the heart; and (b) whether the reduced blood flow is large enough to stress the heart.  Heart function will be measured as the increase in heart blood flow caused by handgrip exercise. Blood flow in the heart will be measured by ultrasound. The handgrip-induced increase in blood flow will be measured in younger and older hookah smokers before and after smoking charcoal-heated or electrically-heated hookah tobacco, and, for comparison, in age-matched cigarette smokers before and after smoking two cigarettes. Specific aims are: (1) to determine the acute effect of hookah smoking on blood flow to the heart in 24 healthy young adult hookah smokers (aged 21-25 years), compared to 12 young adult cigarette smokers; 2) to determine the acute effect of inhaled CO gas alone (to mimic the hookah-induced CO level of 25 ppm, generally considered to be non-toxic) on blood flow to the heart in a subset of 16 young adult hookah smokers; and (3) to determine the acute effect of hookah smoking on blood flow and heart function in 12 long-term middle-aged hookah smokers (aged 35-49 years), compared to 12 middle-aged cigarette smokers. Study findings may provide new understanding of how hookah smoking impacts the regulation of blood flow to the heart in both young and middle-aged adults.