Hookah (water pipe) smoking is the only form of tobacco abuse on the rise in California and across the U.S, and is the only form of tobacco smoking that is exempt from the Indoor Clean Air Act. While hookah is widely marketed as a safer alternative to cigarettes, the opposite may be true because hookah smokers inhale large amounts of smoke containing substances that may be harmful to human health. For example, in addition to the tobacco smoke, toxic chemicals from the burning charcoal used to heat the tobacco are also inhaled. Surprisingly, very little is known about the effects of hookah smoking on the human heart and blood vessels. Smoking hookah immediately raises heart rate and blood pressure which could result from stimulation of the nerves that control the body’s circulation. The goal of this grant proposal is to use state-of-the-art clinical research methods to study the effects of hookah smoking on: (1) the blood flow to the heart; (2) the stiffness of the body’s blood vessels; and (3) the nerve activity controlling blood flow to muscle and skin. We predict that hookah smoking causes a decrease in blood flow to the heart, increases the stiffness of large blood vessels, and decreases blood flow to muscle and skin.
This exciting new study will be the first show that hookah smoking is potentially harmful to the human circulatory system. To accomplish our goals, we will recruit sixty healthy, young volunteers who are regular hookah smokers but not cigarette smokers. Volunteers will be assigned to one of three groups, each representing the three primary goals of our study.
In volunteers assigned to group 1, blood flow to the heart will be assessed by taking special ultrasound images of the heart before and after 90-minutes of smoking hookah. In those assigned to group 2, the stiffness of blood vessels will be assessed by placing a pencil-like sensor gently against the wrist to record a blood pressure signal from the pulse. In volunteers in group 3, the nerve activity controlling blood flow to muscle and skin will be measured using a very small needle (smaller than an acupuncture needle) placed into a nerve in the leg. In addition, blood flow to the lower leg will be assessed by a technique called venous occlusion plethysmography which measures changes in leg circumference following short periods of upper leg compression. Blood flow to the skin will also be assessed by a technique called laser Doppler flowmetry which uses a laser to measure the changes in light reflection from the skin.
The results of these exploratory studies will help identify potentially harmful consequences of hookah smoking on the human heart and blood vessels. Furthermore, the findings will position our laboratory to embark on a new exciting line of research to fully explore the underlying causes of the potentially harmful consequences of hookah smoking. We expect our findings to change public health policy and reduce the public health burden of this currently unregulated form of tobacco use.