Creatine kinase (CK) is an enzyme that uses ATP to convert creatine into phosphocreatine and adenosine diphosphate. It is an enzyme found in the inner mitochondrial membrane. Creatine kinase is a marker of tissue damage. There are three isoenzymes of creatine kinase: skeletal muscle CK-MM, myocardium CK-MB, & brain and smooth muscle CK-BB. Elevated levels are found in patients suffering from heart attack, severe muscle breakdown, and muscular dystrophy.
A study found increased levels of creatine kinase in the muscle biopses of patients with postviral fatigue syndrome. A study measured plasma creatine kinase as a surrogate measure of a lowered oxidative phosphorylation in skeletal muscle of ME/CFS patients (n=15) and healthy controls. They found low plasma creatine kinase levels before and 24 hours after an exercise challenge in ME/CFS patients and healthy controls. This suggested muscle mitochondria were normal, since 24 hours after strenuous exercise CK did not leak to the blood, as is the case in patients with defective oxidative phosphorylation. A 2019 study found markedly reduced serum CK concentrations in severe ME/CFS (n=56), but not in less severe cases.
References[edit | edit source]
- Archard, L. C.; Bowles, N. E.; Behan, P.O.; Bell, E.J.; Doyle, D. (1988). "Postviral fatigue syndrome: persistence of enterovirus RNA in muscle and elevated creatine kinase". Journal of the Royal Society of Medicine. 81 (6): 326–329. doi:10.1177/014107688808100608. ISSN 0141-0768. PMID 3404526.
- Vermeulen, Ruud CW; Kurk, Ruud M; Visser, Frans C; Sluiter, Wim; Scholte, Hans R (December 2010). "Patients with chronic fatigue syndrome performed worse than controls in a controlled repeated exercise study despite a normal oxidative phosphorylation capacity". Journal of Translational Medicine. 8 (1). doi:10.1186/1479-5876-8-93. ISSN 1479-5876. PMC 2964609. PMID 20937116.
- Nacul, Luis; de Barros, Barbara; Kingdon, Caroline; Cliff, Jacqueline; Clark, Taane; Mudie, Kathleen; Dockrell, Hazel; Lacerda, Eliana (April 10, 2019). "Evidence of Clinical Pathology Abnormalities in People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) from an Analytic Cross-Sectional Study". Diagnostics. 9 (2): 41. doi:10.3390/diagnostics9020041. ISSN 2075-4418.
enzyme a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.
mitochondria Important parts of the biological cell, with each mitochondrion encased within a mitochondrial membrane. Mitochondria are best known for their role in energy production, earning them the nickname "the powerhouse of the cell". Mitochondria also participate in the detection of threats and the response to these threats. One of the responses to threats orchestrated by mitochondria is apoptosis, a cell suicide program used by cells when the threat can not be eliminated.
membrane The word "membrane" can have different meanings in different fields of biology. In cell biology, a membrane is a layer of molecules that surround its contents. Examples of cell-biology membranes include the "cell membrane" that surrounds a cell, the "mitochondrial membranes" that form the outer layers of mitochondria, and the "viral envelope" that surrounds enveloped viruses. In anatomy or tissue biology, a membrane is a barrier formed by a layer of cells. Examples of anatomical membranes include the pleural membranes that surrounds the lungs, the pericardium which surrounds the heart, and some of the layers within the blood-brain barrier.