Here’s another reason why you should stop smoking – a new study from University of Illinois at Chicago has shown that prolonged exposure to cigarette can alter the shape of the heart.

The research conducted using a rat model showed that prolonged exposure can increase levels of the stress hormone norepinephrine and enzymes in the heart that have the potential to reshape the left ventricle.

Over the period of five weeks, the researchers found that cigarette smoke turned on enzymes called mitogen-activated protein kinases linked to cell growth and survival in heart muscle.

Lead researcher Mariann Piano, professor of biobehavioural health science in the UIC College of Nursing and said that 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," she said.

"However, the effect of nicotine on the initiation and progression of cigarette smoke-mediated cardiovascular events remains controversial," she added.

The study 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.

The 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 is published in the European Journal of Heart Failure.