Johns Hopkins University medical scientists for the first time have pinpointed how – and why – exercise is so beneficial in preventing heart disease in people with type 2 diabetes.
A detailed study of heart muscle function in mice has exercise found triggers the heart to use greater amounts of beneficial fatty acids that effectively counteract the damaging effects of high blood sugar and boost the heart's pumping ability in several ways.
The findings, published in the journal Diabetes, also reveal the complex chain of events that lead to life-threatening heart failure in diabetics.
"Our work offers a new view of the role of fatty acids in diabetic hearts under stress [as during exercise], and suggests potential new therapies to improve heart function," said researcher Miguel Aon, with the Johns Hopkins University School of Medicine. "It has been commonly assumed that fatty acids were detrimental to heart muscle function, but our study showed the opposite to be true in the diabetic heart."
For the study, researchers examined the impact of glucose (blood sugar) and fatty acids, which are different types of fuel that provide energy to heart cells and how they affect heart muscle function.
The research involved specially bred diabetic mice, which have long been used as models to study human diabetes because the disease in the rodents mimics the disorder in humans.
In their experiments, the researchers fed normal and diabetic mice excess glucose and stimulated their hearts to beat faster. While the normal hearts were able to handle the increased glucose and pump normally, the diabetic hearts could not manage the load and pump normally.
They then repeated the experiments but fed the mice twice the usual amount of fatty acids. "We found that the function of the normal heart did not change, but to our surprise, the diabetic hearts improved to the level of the normal hearts," said co-researcher Dr. Nazareno Paolocci.
The researchers also found that the fatty acids counteracted impairments in the function of diabetic hearts caused by high blood sugar. They noted aerobic exercise breaks up stored fatty acids to provide more fuel to the heart.
The study was funded by the National Heart Lung and Blood Institute of the National Institutes of Health.