St. Louis, Aug. 10, 2007 Heart disease hits people with diabetes twice as often as people without diabetes. In those with diabetes, cardiovascular complications occur at an earlier age and often result in premature death, making heart disease the major killer of diabetic people. But why is heart disease so prevalent among diabetics?
To help answer that question, researchers at Washington University School of Medicine in St. Louis have been analyzing the fat (lipid) composition of heart tissue from laboratory mice with diabetes. They have found that heart cells of diabetic mice lose an important lipid from cellular components that generate energy for the heart, and their latest research shows this happens at the very earliest stages of diabetes. "Diabetic hearts run mostly on fats for fuel because glucose isn't readily available to them," says Richard Gross, M.D., Ph.D., director of the Division of Bioorganic Chemistry and Molecular Pharmacology and professor of medicine, of chemistry and of molecular biology and pharmacology. "Unfortunately, this change in metabolism distorts the lipid composition of cell membranes causing abnormal physical properties and cellular dysfunction." The important lipid that the researchers found to be decreased in diabetes is cardiolipin. "Cardiolipin" literally means heart fat, and the term was coined because cardiolipin was first discovered in beef hearts and is one of the most abundant lipids in heart tissue. This lipid has unusual physical properties that are essential for the operation of the energy-producing cell structures called mitochondria. When mitochondria lose a lot of their cardiolipin, they malfunction. Their malfunction not only interferes with the energy supply of heart muscle cells, it also increases the amount of damaging oxygen-containing substances in the cells, creating unhealthy conditions that can lead to heart problems. Interestingly, a rare genetic disorder Barth syndrome he