The onset of any physical exercise program causes muscle pain that can hinder movements as simple as getting up from a sofa. With time and a little persistence, the muscles become accustomed to the effort, developing more strength and endurance.
Researchers affiliated with Harvard University in the United States and the University of São Paulo (USP) in Brazil describe the cellular mediator that makes this adaptation to exercise possible in the journal Cell.
The mediator is succinate, a metabolite hitherto known only for its participation in mitochondrial respiration. The authors of the article include Julio Cesar Batista Ferreira, a professor at USP's Biomedical Sciences Institute (ICB) and a member of the Center for Research on Redox Processes in Biomedicine (Redoxome), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP (São Paulo Research Foundation), and postdoctoral fellow Luiz Henrique Bozi, who conducted the investigation while he was a research intern at Harvard with FAPESP's support.
Our results show that succinate leaves muscle cells during exercise and sends their neighbors signals that induce a process of muscle tissue remodeling. The motor neurons create new ramifications, the muscle fibers become more uniform to gain strength on contracting, and blood sugar uptake increases in all cells to produce ATP [adenosine triphosphate, the cellular fuel]. There's an increase in efficiency." Julio Cesar Batista Ferreira, Professor, USP's Biomedical Sciences Institute (ICB)
The findings reported in the article are based on a large number of experiments with animals and human volunteers. The first entailed comparisons of more than 500 metabolites present in mouse leg muscles before and after the mice ran on a treadmill until they were exhausted.
"Besides muscle fibers, muscle tissue also contains immune, nerve, and endothelial cells. If each one was a house, the streets between houses would be the interstitium or interstitial space. We isolated and analyzed each of the houses as well as the streets to find out what changes in the neighborhood after exercise, and observed a significant increase in succinate only in muscle fibers and interstitial spaces," Ferreira…