University of Texas Medical Branch at Galveston researchers believe they've found a way to use widely available blood pressure drugs to fight the muscular weakness that normally accompanies aging.
The discovery draws on research linking the loss of muscle mass with age-related changes in the behavior of the hair-thin blood vessels, or capillaries, which supply muscles with the amino acids they need for growth.
"When a young person eats food, insulin secretion causes the blood vessels in the muscle to dilate, so a lot of blood goes into the muscle and a lot of amino acids are available to build muscle proteins," said UTMB professor Elena Volpi, senior author of a paper on the work ("Pharmacological vasodilation improves insulin-stimulated muscle protein anabolism but not glucose utilization in older adults") now available in the "Online Ahead of Print" section of the journal Diabetes. "Older people's blood vessels have far less response to insulin, but we found that if you give them a drug that causes them to dilate, you can increase the nutritive flow to the muscles and completely restore normal growth."
Drugs that induce blood vessels to widen, called vasodilators, are commonly used to control high blood pressure and prevent angina. The UTMB study used sodium nitroprusside, a drug used in hospitals and administered intravenously.
The researchers enrolled 12 healthy older volunteers for the study, and separated them randomly into two six-person groups. Working in UTMB's Clinical Research Center, the investigators performed the delicate task of inserting catheters into the arteries and veins feeding and draining the subjects' leg muscles, and then used the arterial catheter to infuse the muscles with insulin at levels similar to those generated by a meal. One group of volunteers was given the vasodilator drug, while the other received a placebo.