| Theme |
Muscle and exercise physiology on mineral metabolism |
| Title |
Importance of inorganic phosphate in skeletal muscle health |
| Author |
Katsuhito Mori |
Department of Nephrology, Osaka City University Graduate School of Medicine |
| Author |
Masaaki Inaba |
Department of Nephrology, Osaka City University Graduate School of Medicine / Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine |
| [ Summary ] |
Skeletal muscle, which mainly consists of myosin and actin filaments, is uniquely characterized by its ability to contract. Myosin and actin form a protein complex (cross-bridge) by attachment of the myosin head on the actin filament which is involved in force generation. Intracellular Ca2+ released from the sarcoplasmic reticulum plays a critical role in muscle contraction. Muscle fatigue, defined as the decline of muscle performance, is regulated by various factors. Among those, inorganic phosphate (Pi) is known to be a negative regulator of muscle contraction by inhibiting Ca2+ release and/or Ca2+ sensitivity in muscle fiber. Clinically, Pi seems to be associated with force production in skeletal muscle. For example, a significant inverse relationship between intracellular Pi and muscle force was found following the rehabilitation after cast immobilization in patients with ankle fracture. Further studies will be necessary to confirm the impact of Pi on muscle force generation, especially in the elderly with sarcopenia. |