Chronic heart failure presents serious challenges not only because of its impact on the heart, but also because it causes changes in skeletal muscle that affect a person’s overall health. An important study by Sofia Gitler, PhD, Ibrahim Ramirez-Soto, PhD, Aura Jiménez-Garduño, PhD, and Alicia Ortega, PhD, of the National Autonomous University of Mexico provides new insights into how muscles adapt to this condition. The findings, published in the International Journal of Molecular Sciences, highlight biological adjustments that help maintain muscle function during long-term cardiac stress.
“Difficulty with physical activity and muscle weakness are common symptoms of chronic heart failure,” Dr. Gitler explains. However, this study reveals the surprising resilience of muscle performance, providing potential new avenues for treatment.
Dr. Gitler et al. The details of muscle cell behavior were explored using a surgically created rat model of chronic heart failure. The rat model is an experimental system that uses rats to simulate human diseases for research. Three months after causing heart failure accompanied by extensive myocardial infarction, the team observed significant chemical changes in specific parts of the skeletal muscle cells. “Increased activity of proteins that control calcium and glucose in muscle cells appears to protect against energy loss and fatigue,” Dr. Gitler and others note. Calcium is essential for muscle contraction, and glucose is the main source of energy. The changes were profound—calmodulin activity increased fivefold and glucose transporter activity increased sevenfold compared with unaffected rats.
One of the most remarkable findings is that the mechanical properties of muscles, such as their ability to contract and recover from fatigue, remain unaffected by chronic heart failure. Mechanical properties refer to how a muscle performs physical tasks, including producing force and withstanding stress. The discovery challenges long-held beliefs that muscles inevitably degrade and suggests that the body has built-in ways to counteract these effects at a cellular level.
Dr. Gitler and colleagues highlighted the role of nitric oxide, a molecule known for improving blood flow. Blood flow ensures that the muscles receive enough oxygen and nutrients to function. Its levels are higher in rats with chronic heart failure, which may help maintain proper circulation and muscle function. “This may explain why muscle strength is preserved despite the widespread effects of heart failure,” Dr. Gitler said.
Additionally, the study also draws attention to glucose transporters, which respond to insulin to support energy supply to muscles. Insulin is a hormone that helps regulate blood sugar levels. This increase in protein levels helps muscles obtain energy during prolonged activity. Likewise, increased activity of calmodulin prevents dangerous calcium buildup in cells, protecting cells from damage.
Looking at the broader implications, the researchers believe understanding these natural adaptations may lead to better treatments. Treatment may include improving the body’s ability to regulate muscle energy and calcium. Methods that boost glucose transport or calcineurin may help people with muscle fatigue or weakness caused by chronic disease.
Although these findings are promising, Dr. Gitler and colleagues emphasize that further research is needed to see whether these mechanisms also apply to humans and how they can be targeted with treatments. This study provides a deeper understanding of how chronic disease affects muscles and raises hope for developing effective interventions to improve patient outcomes.
Journal reference
Gitler, S., Ramirez-Soto, I., Jiménez-Graduño, A., Ortega, A., “Failure of upregulation of calcium ATPase (PMCA) and GLUT-4 in the transverse membrane of skeletal muscle in a rat model of chronic heart disease ”, International Journal of Molecular Sciences, 2024. DOI: https://doi.org/10.3390/ijms252011180
About the author
Dr. Sophia Gitler is a physician specializing in internal medicine, receiving his medical degree from La Salle University in Mexico City and completing his professional training at the National Autonomous University of Mexico (UNAM). She is involved in various biomedical research through research collaborations between the National Institute of Genomic Medicine and the Department of Biochemistry, School of Medicine at the National Autonomous University of Mexico. On the clinical side, she interned at ABC Medical Center in Mexico City, focusing on comprehensive patient care. Her primary research interests are directed at the health and well-being of older adults, with a particular emphasis on muscle and brain function associated with aging.
Dr. Alicia Ortega She received her MD degree from the National Autonomous University of Mexico (UNAM) School of Medicine and completed her undergraduate internship at the University of Maryland School of Medicine in Baltimore. Then she earned her Ph.D. Doctor of Science from the University of Waterloo, Canada. After completing her PhD, she held postdoctoral research positions in the Department of Biophysics and Biochemistry at the University of Maryland, the Department of Muscle at the Boston Biomedical Research Institute (BBRI), and the Department of Chemistry at MIT. She also serves as a Fellow of the Alexander von Humboldt Foundation and as a Visiting Professor at the Max Planck Institute of Biochemistry in Germany.
Dr. Ortega’s research focuses on biochemical and physiological aspects of skeletal muscle, excitable cell membranes, and membrane protein stability. Over the past 30 years, she has studied phenomena such as fatigue, motor adaptation, and muscular dystrophy at the subcellular level, and more recently explored the brain’s role in controlling movement in diseases such as Parkinson’s disease and epilepsy. She is currently a professor and researcher at the Department of Biochemistry, School of Medicine at the National Autonomous University of Mexico, and a member of the National Academy of Medicine and the Mexican Academy of Sciences.
