Meeting Abstract
Acclimation to hypoxia is associated with changing of the set point of high energy phosphate molecules in skeletal and cardiac muscle, characterized by a reduced phosphocreatine (PCr) to ATP ratio. This response is associated with enhanced hypoxic exercise endurance. β-guanidinopropionic acid (β-GPA) supplementation decreases the PCr/ATP resulting in an energetic challenge that is similar to both exercise and acclimation to hypoxia. In this study, we administered β-GPA to mice for 2 or 6 weeks, and investigated the effect on muscle energetic status, body and muscle mass, basal metabolic rate (BMR), and normoxic and hypoxic exercise tolerance (NET and HET, respectively). PCr /ATP ratios significantly decreased during both treatment times in the β-GPA fed mice compared to control mice. Body and muscle mass significantly decreased after β-GPA treatment compared to controls, and BMR was significantly increased in β-GPA fed mice. NET significantly decreased in the 2-week treatment, but was not significantly different in the 6-week treatment. HET significantly decreased in the 2-week treatment, but in contrast to NET, significantly increased in the 6-week treated mice compared to control mice. We conclude that β-GPA induces a cellular energetic response that is similar to that of chronic hypoxia, and this change is a proximal cause of the enhanced exercise tolerance under hypoxic conditions.
