The contents of high‐energy phosphates in different fibre types in skeletal muscles from rat, guinea‐pig and man.

Publisher Website
Google Scholar
Abstract
The contents of high-energy phosphates at rest were measured in skeletal muscles with different fiber-type composition from rat, guinea pig and man. All muscles studied biochemically were characterized histochemically. Fast-twitch muscles had a higher ATP/ADP ratio than slow-twitch muscles and, with the exception of the tongue in the rat, higher contents of ATP and phosphocreatine. There was an inverse relationship between the content of phosphocreatine and the stainability for succinyl dehydrogenase, which is a marker enzyme for oxidative capacity. The biochemical and histochemical data are discussed in relation to known morphological and functional properties of the different muscle-fiber types. Fast-twitch fibers have a high ATP/ADP ratio favoring a fast acceleration of energy production. The content of phosphocreatine seems to be related to the glycolytic capacity but not to the contraction time. In addition to being an immediate energy source, phosphocreatine functions as a buffer against lactic acidosis.