Researchers have found a way to prevent insulin resistance in burn-injured rats, a finding that, while still quite preliminary, could eventually save burn victims' lives and speed their recovery.
The researchers honed in on the renin-angiotensin system (RAS) as the key to preventing insulin resistance -- a unique line of inquiry in burn research, according to lead author Sherry O. Kasper. About 70% of serious burn victims develop insulin resistance, a condition marked by elevated levels of glucose and insulin.
Reversing the condition has the potential to reduce mortality, length of stay in intensive care and infection rates among severe burn patients, Kasper said. The American Physiological Society (APS) awarded Kasper a Caroline tum Suden/Frances A. Hellebrandt Professional Opportunity Award in recognition of the exemplary research. Kasper also received the Mead Johnson Research Award in Endocrinology and Metabolism for the best abstract in endocrinology and metabolism by a graduate student, resident or postdoctoral fellow.
Insulin resistance occurs when the body senses glucose overload and attempts to reduce it by producing more insulin. When the additional insulin is unable to moderate the glucose, the body releases even more insulin. The result: elevated levels of both glucose and insulin. Burn-related insulin resistance can last for months, Kasper said.
Kasper became interested in RAS while studying the system as it relates to diabetes, blood pressure and aging. Karlstad, a physiologist, is an expert in trauma and burn. Knowing that RAS plays an important role in the development of insulin resistance in diabetic patients, they theorized that blocking the RAS might prevent the condition in burn patients.
"Our study shows that keeping blood glucose levels normal can be done by treating the insulin resistance rather than by giving more insulin, which opens the possibility for faster recoveries and improved outcomes," Karlstad said. The researchers used a simple but untried method of preventing insulin resistance: they administered losartan, a drug which blocks the RAS, to rats that received an insensate third-degree burn. An insensate burn is one that damages nerves and prevents pain signals from reaching the brain.
"Losartan treatment completely reversed the insulin resistance of burn injury, returning it back to normal levels," Kasper said the study found. Burn-injured rats that did not receive the losartan showed a 124% increase in insulin resistance while burn-injured rats that received the treatment showed no evidence of insulin resistance. "This suggests that insulin resistance caused by burn injury is due in part to the renin-angiotensin system," she said.
Physiologists have long known that burn victims have elevated blood glucose levels. Until recently, they thought the body needed the additional glucose to heal the wounds. However, a recent study showed that maintaining glucose at normal levels can decrease mortality and diminish other negative outcomes of severe burns.
When glucose is not properly metabolized by the body, it causes muscle breakdown, increases the chance of septicemia, and can harm the lungs and kidneys, Kasper said. As a result of high glucose levels, burn patients can suffer massive organ injury and organ failure.