Muscle wasting in colon cancer may reduce heart function, according to a study published in the International Journal of Oncology (2010 Aug;37(2):347-53).

For the study, led by Martha Belury, professor of human nutrition at Ohio State University, researchers compared mice with and without colon cancer tumors. At day 14 of the study, when the mice with tumors were clearly losing weight, they used echocardiography to measure cardiac function in all of the mice.

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The evaluation revealed that mice with tumors as a group had a heart rate of almost 21% fewer beats per minute on average and pumped significantly less blood than did the heart of the healthy mice. When researchers observed the mice 3 days later, they reported a 23% difference in body weight between the mice with cancer and those without tumors.

According to the authors, the results support the idea that insufficient heart performance may be responsible for fatigue symptoms, leading to less exercise and more severe muscle wasting.

Furthermore, when researchers examined the heart tissue of all of the mice using electron microscopy they found a number of signs of damage in the heart muscle tissue of mice with muscle wasting, including an increase in fibrous tissue and changes in mitochondria.

In addition, by examining gene function in the heart tissue, researchers found that proteins associated with power generation in muscle had converted from their adult form to a fetal type in the hearts of mice with muscle wasting.

“The heart was still trying very hard to maintain function and structure, so it was including this kind of action to try to heal itself but it just couldn’t. There was too much going on for this to work,” Belury said. “We wonder if we could harness some of this knowledge into a way of reversing the heart disease.”