Vessels are to blame for senile muscle weakness

Researchers at the Medical Department of the University of Texas at Galveston, working under the guidance of Dr. Elena Volpi, have found that the cause of physical weakness in the elderly is a violation of the biochemical mechanism that dilates blood vessels in response to an increase in insulin levels. The results of this work were published on May 19 in the preliminary on-line version of the Journal of Clinical Endocrinology & Metabolism in the article "Insulin Stimulates Human Skeletal Muscle Protein Synthesis via an Indirect Mechanism Involving Endothelial-Dependent Vasodilation and Mammalian Target of Rapamycin Complex 1 Signaling".

Usually, the smallest capillaries of muscles are in a passive state (that is, there is no lumen between their walls), however, after a meal stimulating the release of insulin in young people, the lumen of these vessels opens wide, ensuring the delivery of nutrients to muscle cells. Unfortunately, in old age, insulin ceases to have a vasodilating effect.

According to Dr. Volpi, in their work, the authors wanted to find out whether a decrease in the ability of muscle capillaries to expand is just one of the side effects of aging or one of the main reasons for a decrease in the level of muscle protein synthesis in the elderly. It is known that the ingress of nutrients and insulin into the muscle cell triggers many intracellular signaling mechanisms associated with the growth of muscle tissue, and the data obtained by the researchers prove that vasodilation (expansion of the lumen of blood vessels) is a necessary condition for starting these processes. Curiously, the signaling pathway of the target of rapamycin, a protein associated with various manifestations of aging at the cellular level, also plays an important role here.

The authors came to this conclusion after conducting an experiment in which they injected a dose of insulin equivalent to the amount of this hormone produced by the body after eating into the femoral muscles of two groups of young people. The subjects of the experimental group were previously injected with a drug that blocks vasodilation. At the end of the experiment, the researchers, according to the degree of incorporation of chemical labels, assessed the levels of protein synthesis in the muscles of the participants. They also analyzed biopsies of their muscle tissue for the activity of biochemical processes associated with muscle growth.

It turned out that under the conditions of vasodilation blockade, the muscles of young people behave like the muscles of older people, which is manifested by blurred reactions of protein metabolism and lack of muscle tissue growth.

The results obtained indicate potential methods of combating aging-associated muscle weakness and associated deterioration of health and quality of life.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru According to ScienceDaily: Muscle Loss in Elderly Linked to Blood Vessels' Failure to Dilate.

24.05.2010