When the heart deviates from its normal source of energy, congestive heart failure can develop. From the German Cancer Research Center, scientists are showing the importance of metabolism in the science of heart failure.
Healthy hearts use fatty acids for 75 percent of their energy source, but weak hearts switch to using carbohydrates as energy. In the new study, researchers discovered that, on its own, the shift from fatty acids to carbohydrates leads to congestive heart failure.
Congestive heart failure, also known as cardiac insufficiency, is characterized by the heart’s failure to pump enough blood throughout the body. Symptoms like shortness of breath, buildup of watery fluid, and “diminished exercise capacity” are seen, and the condition is eventually lethal.
Notch-1, a receptor molecule, is at the center of this study’s discovery. Notch-1 is responsible for ferrying fatty acids from the blood to the heart muscle, where they can be used as energy. Without Notch-1, another signaling pathway is activated: mTOR. This pathway triggers unhealthy growth of the heart muscle, further contributing to heart failure.
In their studies, scientists inactivated Notch-1 in mice and genetically modified mice to contain inactivated Notch-1 in cells lining the surface of the blood vessels. Both groups of mice developed heart failure.
"For nutrients to travel from the blood vessels into the heart muscle, they must be transported through the endothelial cells,” explained first author Markus Jabs. “With Notch-1 inhibited, the heart has less fatty acids available and it must shift to glucose as an energy source.”
While it may be possible to to counter the effects of metabolic shift from fatty acids to carbohydrates by blocking the mTOR signaling pathway or via a low-carb diet, team leader Andreas Fischer doesn’t suggest either actions as a solution to the problem illustrated by the findings in the new study.
"However, this does not mean that we should completely erase carbohydrates from our meal plan in order to prevent heart failure," Fischer said. "But our results show the immense impact that a change in metabolism, such as in inherited or acquired metabolic disorders, has on the course of congestive heart failure."
The present study was published in the journal Circulation.