Prolonged cigarette smoke exposure can perk up levels of a stress hormone in the heart that can effect in potentially reshaping the left ventricle, according to new research conducted on rats.
In a Chicago University (Illinois) study, a five-week exposure to cigarette smoke was associated with the activation of enzymes called mitogen-activated protein kinases that govern cell growth and survival in heart muscle.
Activation of these enzymes may be a key event in cigarette smoke-induced heart injury.
Cigarette smoke contains more than 4,000 different chemicals, one of which is nicotine.
To date, small clinical trials of nicotine replacement therapies have not shown increased cardiovascular risk, even in patients with cardiovascular disease. This suggested the need to study cigarette smoke as a whole.
In the new study, rats were exposed either to cigarette smoke or to normal room air. After five weeks, the animals were examined by echocardiography. Heart tissue was examined under the microscope and by Western blot analysis, used to detect specific proteins in tissue samples.
The results showed exposure to cigarette smoke was associated with significant changes in the shape of the left ventricle, the heart’s main pumping chamber, and an increase in the levels of the activated forms of the enzymes in the heart muscle.
Researchers also found increased levels of norepinephrine, a hormone released when a stressful event causes any of a host of physiological changes, in urine samples taken from the animals.
The study was published in the European Journal of Heart Failure.
