ABSTRACT
Creatine (Cr) is a metabolite that plays a vital role in bioenergetics.
Cellular energy, during increases in instantaneous demand, is
supplied by generation of adenosine triphosphate (ATP) through
the creatine kinase (CK) reaction (Eq. 18.1) [1]. During the CK
reaction, ATP is produced from the conversion of phosphocreatine
(PCr) and adenosine diphosphate (ADP) to Cr [2]. When cells
undergo processes that require an increase in energy, like muscle
contraction, PCr is depleted to maintain the available supply of ATP.
This mechanism allows cells access to an immediate energy supply,
without requiring storage of large amounts of ATP [3]. Once the
instantaneous energy demand is reduced, generation of ATP through
Krebs cycle or glycolysis leads to a subsequent increase in PCr levels.
In muscular diseases and metabolic disorders, CK kinetics are often
affected [4]. Oxidative phosphorylation (OXPHOS), the process by
whichmitochondria produce ATP, is often impaired in such diseases,
indicated by delayed recovery of PCr.
