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Researchers Study Link Between Secondhand Smoke, Cardiovascular Disease

An interdisciplinary MCG team is probing whether exposure to secondhand smoke increases the chance that children with a family history of cardiovascular disease will develop the disease.

If those children also have a variation in at least one of four genes responsible for metabolizing nicotine, their risk may increase even more because nicotine might stay in the body longer and do more damage.

The team will study 585 people age 1520 who have a parent, grandparent or both with essential hypertension and/or a heart attack by age 55.

“What I hope to take away from this is more information for parents and caregivers about the risk of future disease that their behavior places on their child,” said Dr. Martha Tingen, a nurse researcher at MCG’s Georgia Prevention Institute and principal investigator on the $220,000 National Institute of Nursing Research grant.

Researchers will look for adverse clinical cardiovascular measures, including reduced ability of arteries to dilate; the blood encountering increased resistance as it travels through vessels; higher blood pressure; and an increase in the size of the pumping chamber of the heart—a result of pumping against elevated pressure.

Exposure to the damaging effects of nicotine and other pathogens in smoke may also cause a vicious cycle in the body. “It likely damages cells on the innerwall lining of blood vessels, which results in less adaptive capacity of the vessels and arteries. This may cause greater strain on the heart,” said Dr. Tingen.

Children exposed to secondhand smoke who have a variation of one or more of the genes that metabolize nicotine— CYP1A1, GSTM1, GSTT1 and CYP2A6— can experience cellular damage because the nicotine does not leave the body as quickly, she said. “And if that’s happening, they’re going to have more of these adverse preclinical cardiovascular measures that predispose them to developing cardiovascular disease.”

Almost half a million Georgia children are exposed to secondhand smoke in the home, and up to 60,000 cardiovascular deaths each year in the United States are linked to nonsmokers’ exposure to secondhand smoke, Dr. Tingen said.

The researchers will unfreeze the blood samples, which come from a 15year longitudinal database kept by Dr. Frank Treiber, MCG vice president for research and a GPI child psychologist. Then Drs. Yanbin Dong and Haidong Zhu, MCG molecular geneticists, will seek variations in the identified genes. Dr. Gaston Kapuku, a GPI cardiologist, will help interpret the cardiovascular measures. Finally, the blood samples will be analyzed for cotinine levels, a metabolized version of nicotine and a reliable indicator of secondhand smoke exposure.

“If kids are exposed in the home and they have genetic alterations that make nicotine stay in the body longer, there’s an increased likelihood they’re at greater risk for developing cardiovascular disease,” said Dr. Tingen.

Jennifer Hilliard