GALVESTON, Texas, May 21 (UPI) — Muscles age because of the way a network of blood vessels that threads through muscles responds to the hormone insulin, U.S. researchers said.
Researchers at the University of Texas Medical Branch at Galveston said blood vessels open wide and allow nutrients to reach muscle cells when young people naturally release insulin after eating a meal.
The study, published in the Journal of Clinical Endocrinology & Metabolism, suggests insulin in elderly people does not result in the muscle repairing — “vasodilating” — effect.
“We found that by blocking vasodilation, we reproduced in young people the entire response that we see in older persons — a blunting of muscle protein response and a lack of net muscle growth,” study senior author Dr. Elena Volpi said in a statement. “In other words, from a muscle standpoint, we made young people look 50 years older.”
Volpi and colleagues infused insulin equivalent to the amount generated in response to a single meal into the thigh muscles of two sets of young volunteers. One set was given a drug that blocked vasodilation, while the other set responded normally.
Muscle protein synthesis levels were measured using chemical tracers and muscle tissue biopsies were done, Volpi said.
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