title: Protein kinase A catalytic subunit alters cardiac mitochondrial redox state and membrane potential via the formation of reactive oxygen species.
abstract: BACKGROUND
  The identification of protein kinase A (PKA) anchoring proteins on mitochondria implies a direct effect of PKA on mitochondrial function. However, little is known about the relationship between PKA and mitochondrial metabolism.
  
  
  RESULTS
  The effects of PKA on the mitochondrial redox state (flavin adenine dinucleotide (FAD)), mitochondrial membrane potential (DeltaPsi(m)) and reactive oxygen species (ROS) production were investigated in saponin-permeabilized rat cardiomyocytes. The PKA catalytic subunit (PKAcat; 50 unit/ml) increased FAD intensities by 56.6+/-7.9% (p<0.01), 2'7'-dichlorofluorescin diacetate (DCF) intensities by 10.5+/-3.3 fold (p<0.01) and depolarized DeltaPsi(m) to 48.1+/-9.5% of the control (p<0.01). Trolox (a ROS scavenger; 100 micromol/L) inhibited PKAcat-induced DeltaPsi(m), FAD and DCF alteration. PKAcat-induced DeltaPsi(m) depolarization was inhibited by an inhibitor of the inner membrane anion channel (IMAC), 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS: 1 micromol/L) but not by an inhibitor of mitochondrial permeability transition pore (mPTP), cyclosporine A (100 nmol/L).
  
  
  CONCLUSIONS
  PKAcat alters FAD and DeltaPsi(m) via mitochodrial ROS generation, and PKAcat-induced DeltaPsi(m) depolarization was not caused by mPTP but rather by DIDS-sensitive mechanisms, which could be caused by opening of the IMAC. The effects of PKA on mitochondrial function could be related to myocardial function under the condition of extensive beta-adrenergic stimulation.
authors.affiliation: Division of Cardiology, Internal Medicine III, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Nagasaka
authors.forename: Hideki
authors.initials: H
authors.lastname: Katoh
authors.forename: Chun Feng
authors.initials: CF
authors.lastname: Niu
authors.forename: Saori
authors.initials: S
authors.lastname: Matsui
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Urushida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Satoh
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Hideharu
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D002384:Catalysis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D007473:Ion Channels; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008929:Mitochondria, Heart / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D021122:Protein Subunits; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D021122:Protein Subunits; D017382:Reactive Oxygen Species; D017868:Cyclic AMP-Dependent Protein Kinases