title: Direct evidence for the control of mitochondrial respiration by mitochondrial creatine kinase in oxidative muscle cells in situ.
abstract: The efficiency of stimulation of mitochondrial respiration in permeabilized muscle cells by ADP produced at different intracellular sites, e.g. cytosolic or mitochondrial intermembrane space, was evaluated in wild-type and creatine kinase (CK)-deficient mice. To activate respiration by endogenous production of ADP in permeabilized cells, ATP was added either alone or together with creatine. In cardiac fibers, while ATP alone activated respiration to half of the maximal rate, creatine plus ATP increased the respiratory rate up to its maximum. To find out whether the stimulation by creatine is a consequence of extramitochondrial [ADP] increase, or whether it directly correlates with ADP generation by mitochondrial CK in the mitochondrial intermembrane space, an exogenous ADP-trap system was added to rephosphorylate all cytosolic ADP. Under these conditions, creatine plus ATP still increased the respiration rate by 2.5 times, compared with ATP alone, for the same extramitochondrial [ADP] of 14 microM. Moreover, this stimulatory effect of creatine, observed in wild-type cardiac fibers disappeared in mitochondrial CK deficient, but not in cytosolic CK-deficient muscle. It is concluded that respiration rates can be dissociated from cytosolic [ADP], and ADP generated by mitochondrial CK is an important regulator of oxidative phosphorylation.
authors.affiliation: Institute of Cell Biology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland. laurence.kay@cell.biol.ethz.ch
authors.forename: L
authors.initials: L
authors.lastname: Kay
authors.forename: K
authors.initials: K
authors.lastname: Nicolay
authors.forename: B
authors.initials: B
authors.lastname: Wieringa
authors.forename: V
authors.initials: V
authors.lastname: Saks
authors.forename: T
authors.initials: T
authors.lastname: Wallimann
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003402:Creatine Kinase / Q000502:physiology*; D007527:Isoenzymes; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption
chemical_list: D007527:Isoenzymes; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003402:Creatine Kinase